Quest 3(4)

Science for for South South Africa Africa Science

ISSN 1729-830X ISSN 1729-830X

Volume 3 3 •• Number Number 2 4 •• 2007 2007 Volume R25 R20

A c Aa cdaedmeym yo fo fS c i ei ennccee ooff SS o h AAffrri c i caa Sc ou u tt h

The world needs science…

Science needs women.

This conviction has united L’OréaL and UNESCO since 1998, when they joined forces to promote women in scientific research by creating the For Women in Science partnership.

The For Women in Science partnership is comprised of three programs: The L’ORÉAL-UNESCO Awards, which recognize five top women researchers, one per continent, for their excellence in scientific research with a $100 000 Award.

The UNESCO-L’ORÉAL International Fellowships worth $40 000 each, granted to fifteen promising young researchers, to enable them to carry out research projects outside their country of origin.

The National Fellowships, which began in 2001 with L’ORÉAL Poland, and by the end of 2008, will exist in 56 countries, to encourage young women to continue their scientific research careers within their country of origin.

Prof Ameenah Gurib-Fakin, International Laureate for Africa 2007, concentrating plant extracts with rotary evaporator in the lab at the University of Mauritius.

Since 1998, 47 L’ORÉAL-UNESCO Award Laureates have been recognized for their careers and 105 international Fellows have been encouraged to pursue their scientific vocations. The program of National Fellowships, already in place in over 20 countries, has up to now permitted 205 young women to continue their research.

L’OréaL South africa, in association with Unesco and the Department of Science and Technology offers Fellowships in recognition of the academic achievements of South africa’s top women PhD graduates in the Life or Material Sciences.

Carol Simon National Fellow 2005 - Life Sciences

Jacqueline Weyer National Fellow 2006 - Life Sciences

For Information on the FWIS International program and local Initiative, please contact: Marie Irissou L’Oréal South Africa Tel: 27 11 286 0708 Fax: 27 11 286 0880 Email: mirissou@za.loreal.com www.forwomeninscience.com

T H E L’ O R É A L – U N E S C O P A R T N E R S H I P

Cover stories

26

Ancient artifacts, adornment, and archaeology Sian Tiley-Nel Mapungubwe’s precious beads and figurines reveal Africa’s distant past 3

Hidden worlds behind the Milky Way Renée C. Kraan-Korteweg and Patrick A. Woudt

8

The Zone of Avoidance, where galaxies have hidden since time began The state of our environment Rudi Pretorius Monitoring South Africa’s natural resources

Contents VOLUME 3 • NUMBER 4 • 2007

Regulars

Features 12

Life in estuaries

Fact files Environmental facts for South Africa (p. 11) • Some Mapungubwe facts (p. 28) • X-ray crystallography and vitamin B12 (p. 37)

■ Pipefish survival Monica Mwale Vulnerable organisms indicate ecosystem health

14

Science news Fighting junk food; Talking heads (p. 40) • How elephants run; Ozone threatens carbon sinks; Beware iPods in a thunderstorm; Tips for decision-makers (p. 43)

■ Fish larvae smell their way to safety Nikki James Discovering what signals attract fishes to their nurseries

22 23

Measuring up QUEST interviews Women in engineering Danai Magugumela and Althea Povey Two prominent civil engineers and their road to success

17

What’s that brown haze over Cape Town?

29

Repository of natural and human heritage

Patience Gwaze Urban air pollution that’s dangerous to health

20

Colour without colour – new generation cosmetics

30

Careers Working with heritage (p. 30) • Studying astrophysics for related careers (p. 40)

31

Books Gardens big and small

38

Viewpoint Women in science – cresting the wave or wiped out?

Jason Eason

Annette Combrink

Photonics and optics light up the way forward 40 32

The vitamin B12 story

41

Special feature: Science for the Classroom The search for the missing carbon sink Max Planck Society

Letters to QUEST Future scientists for South Africa Your QUESTions answered Gums, badgers, and economics – Brian van Wilgen

Susan Chemaly The pioneering science of Dorothy Hodgkin

The S&T tourist Mapungubwe National Park

42

ASSAf news Top woman researchers newly elected to ASSAf

42

Diary of events

43

Crossword puzzle

44

Subscription form

45

Back page science • Mathematical puzzle

After page 22

Quest 3(4) 2007 1

Science for for South South AfricA AfricA Science

ISSN 1729-830X ISSN 1729-830X

Volume 3 3 •• Number Number 2 4 •• 2007 2007 Volume r25 r20

A c AA cdAedmeym yo fo fS c I eI eNNccee ooff SS o h AAffrrI c I cAA Sc ou u tt h

A collage of Mapungubwe artefacts and archival images with a background view of the Limpopo River.

Images: Courtesy of the University of Pretoria, Mapungubwe Museum and Archive (copyright reserved).

SCIENCE FOR SOUTH AFRICA

ISSN 1729-830X

Editor Elisabeth Lickindorf Editorial Board Wieland Gevers (University of Cape Town) (Chair) Graham Baker (South African Journal of Science) Phil Charles (SAAO) Anusuya Chinsamy-Turan (University of Cape Town) George Ellis (University of Cape Town) Jonathan Jansen (Stanford University) Correspondence and The Editor enquiries PO Box 1011, Melville 2109 Tel./fax: (011) 673 3683 e-mail: editor.quest@iafrica.com (For more information visit www.questsciencemagazine.co.za) Advertising enquiries Barbara Spence Avenue Advertising PO Box 71308 Bryanston 2021 Tel.: (011) 463 7940 Fax: (011) 463 7939 Cell: 082 881 3454 e-mail: barbara@avenue.co.za Subscription enquiries Astrid Coyle and back issues Tel.: (012) 205 1136 or Tel./Fax: (011) 673 3683 e-mail: quest.subscription@gmail.com or editor.quest@iafrica.com Copyright © 2007 Academy of Science of South Africa

Past and future S

outh Africa’s scientific calendar dedicates the months of August and September to Women in Science and to Heritage, respectively. The word ‘calendar’ comes from the Latin calendarium, meaning ‘account book’, used to keep track of the date when debts were due, so celebrates the debts that the present owes to the past.

‘Heritage’ refers to ‘whatever has been inherited’. Our country’s African heritage has for decades been obscured by our politics, but it’s now coming into its own. The treasures of Mapungubwe (p. 26) highlight the stature of the thriving international trading culture of a thousand or so years ago in the Limpopo valley, and the place of women in that society.

A heritage that people have taken for granted and overexploited on a massive global scale is our natural environment. South Africa’s National State of the Environment Report (p. 8) is an invaluable rallying-point for considering, as a matter of urgency, how best to preserve and nurture the inherited benefits of which present and future generations are the custodians, and to reverse escalating destruction by unsustainable developments. Lest anyone doubt the inconvenient truths, our pages celebrate South Africa’s researchers who gather and interpret the scientific facts that support, inform, and extend such concerns. Detailed work on pipefishes (p. 12) and on the way in which fish larvae seek out safe havens where they can grow to adulthood (p. 14) testifies to the critical importance of keeping our (underprotected) estuaries healthy; analysis of Cape Town’s air pollution (p. 17) establishes the facts and the dangers to health created by large-scale fuel emissions.

We also remember pioneers who extended the limits of knowledge.

Nobel-prizewinner Dorothy Hodgkin scored twice over – her understanding of crystalline structures saved many lives, and she fearlessly broke through the intellectual and educational restrictions that disadvantaged the talented women of her day (p. 32). Her story demonstrates what a woman can achieve in science once she puts her mind and heart to it, and also how to set about overcoming obstacles and nurturing top scholars for the future. She is a remarkable role model.

More than half of the world’s human population is female, and the pride that women have traditionally taken in their appearance has inspired innovative research in the ever-changing field of cosmetics (p. 20). Their professional abilities, however, have only recently been allowed to develop in fields previously occupied only by men. We interview successful women engineers (p. 23), and this issue emphasizes the scientific achievements of women, ranging from a world leader in astronomy seeking hidden worlds behind the Milky Way (p. 3) to newly-minted Ph.Ds. If the best that’s inherited from the past can combine with the best that women can offer in the worlds of research and applied science, then most certainly a glittering future is assured.

Published by the Academy of Science of South Africa (ASSAf) PO Box 72135, Lynnwood Ridge 0040, South Africa (011) 673 3683 Permissions Fax: e-mail: editor.quest@iafrica.com Subscription rates (4 issues and postage) (For subscription form, other countries, see p.44.)

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The views expressed in this magazine are not necessarily those of the publisher.

2 Quest 3(4) 2007

Join QUEST’s knowledge-sharing activities Write letters for our regular Letters column – e-mail or fax your letter to The Editor. (Write QUEST LETTER in the subject line.)

■ Ask science and technology (S&T) questions for specialist members of the Academy of Science to answer in our regular Questions and Answers column – e-mail or fax your questions to The Editor. (Write QUEST QUESTION in the subject line.)

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■

Renée C. Kraan-Korteweg and Patrick A. Woudt describe amazing discoveries in the previously concealed skies of the Zone of Avoidance.

T

he band of the Milky Way, a superb feature of the night sky, displays the light emitted by hundreds of millions of stars – and by starlight scattered by dust grains – in the disk of our own Galaxy, the Milky Way. We are located about 24 000 light years from its centre in the midst of the fairly thin Galactic disk1.

Our location in our Galaxy hampers the study of the galaxies and their distribution in the part of the sky dominated by the Milky Way. Our view of the Universe is hardly affected when we observe the sky in a direction perpendicular to the plane of the Milky Way. However, observations within the plane of the Galaxy encounter such dense dust that the light of galaxies lying behind the Milky Way are completely absorbed, making them invisible to viewers on Earth. Because it seemed as if galaxies were ‘avoiding’ this region of the sky, it was named the ‘Zone of Avoidance’ (ZOA)2.

Few galaxies have been recognized in the band around the sky where light is absorbed, but the size and shape of this region varies according to the wavelength in which it is viewed. In the optical, as much as a quarter of the Universe is blocked from our view! Astronomers who study the large-scale distribution of galaxies normally avoid the ZOA and concentrate on other parts of the sky, but explorers of this avoided region persist in their efforts, irreverently referring to our gorgeous Milky Way as ‘foreground pollution’.

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Why bother with the ZOA? Does 75–80% of the sky – that is, of our Universe – not offer sufficient territory for exploring the most important questions in astronomy and astrophysics?

The answer is no. The ZOA raises important cosmological questions, and has sparked intensive research efforts in the last couple of decades.

One question is: “Could another nearby Andromeda-like galaxy be hidden by the Milky Way’s light pollution?” If so, it could change the way we explain the formation of the Local Group (LG) – the group of galaxies about 3 million light years in diameter that contains our own Galaxy3.

1. The galactic disk is the major structural component of certain types of galaxy, and it contains stars and (for spirals and irregulars) gas and dust, which orbit the galaxy’s centre. The thickness of the disk is small in relation to its diameter. The disk of our own Galaxy extends some 80 000 light years from the galactic centre. Its total thickness is about 1 500 light years as measured by the distribution of older stars, and just 600 light years for young stars, gas, and dust.

Source: Ian Ridpath (ed.), A Dictionary of Astronomy (Oxford University Press, 2003).

2. The detailed structure of the Zone of Avoidance is irregular, and varies in width between 38° (towards the galactic centre) and 12°, with some fairly transparent regions known as ‘galactic windows’.

3. The Local Group has 36 confirmed members, of which the brightest are the three spirals: the Andromeda Galaxy, our Galaxy, and M33.

The nearest other prominent galaxies (Sculptor and M81 groups) are considerably further away, at about 10 million light years.

Top left and right: Two spiral galaxies that greatly resemble our own Galaxy, the Milky Way. The first, NGC 1232 (left), is seen face-on, revealing the spiral arms with their star-forming regions as well as its central bulge. (If this were a picture of the Milky Way, our Sun would lie about two-thirds out from the centre close to a spiral arm.) The other galaxy, NGC 891, is seen edge-on. While the central bulge is visible above and below the disk of the galaxy, the spiral arms cannot be made out. Moreover, the starlight close to the plane of the disk is almost completely obscured by the light-absorbing dust particles there. Images: ESO (European Southern Observatories) and CFHT (Canada France Hawaii Telescope), respectively.

Above left: These two pictures, one above the other, show optically catalogued galaxies with apparent diameters larger than one arc minute in a projection centred on the disk of the Milky Way with the Galactic Bulge at its centre (that is, an Aitoff or equal area projection in galactic coordinates). In the upper picture, the broad band empty of galaxies makes up more than 20% of the sky. Its form is like a near-perfect negative of the optical light distribution as depicted in the famous composite (shown below it) made by Swedish astronomer Knut Lundmark in 1940, and is well traced by the dust. The red contour marks light obscuration of 1 magnitude in the optical, and corresponds to a reduction in the intensity of the received light by a factor of 2.5.

Above lower right: Optical 3-colour image (obtained with the Isaac Newton Telescope in La Palma) of the Dwingeloo 1 galaxy, originally discovered by Renée Kraan-Korteweg in 1994 at radio wavelengths (see next page). The numerous stars of our Milky Way can be seen in the foreground.

Quest 3(4) 2007 3

Above: Large-scale structure in the local Universe. The image shows 2MASS galaxies colourcoded by redshift (Jarrett, 2004). Familiar galaxies are labelled (numbers in brackets represent redshift). Image: Courtesy of T.H. Jarrett (IPAC/Caltech)

In 1987, seven astronomers (dubbed the Seven Samurai) noticed a systematic pattern of movement over and above the smooth uniform expansion of the Universe. All galaxies in the local Universe – including our own Galaxy – seem to be streaming with a velocity of about 500–600 km/s towards the constellation of Norma.

Such a huge peculiar motion had not been seen before and raised some consternation. The only reasonable explanation was the gravitational attraction of a huge mass concentration existing in that direction of the sky. No prominent, large-scale galaxy agglomeration was visible, however, so this mysterious mass-overdensity was nicknamed the ‘Great Attractor’. The problem was that the apex of this flow motion pointed deep into the Milky Way, to an area of the extragalactic sky that is severely obscured from our view.

Lifting the veil of the Milky Way How do astronomers find galaxies that are so heavily obscured? They apply instruments that survey the sky and reveal objects at different wavelengths4.

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Top: Panel above (left, middle, right): Images based on the Hydra Galaxy cluster, which lies 28° above the Galactic plane (and therefore far from dust interference).

The left-hand picture shows the near-infrared J, H, K5 colour-composite image of an 8 x 8 arcmin field centred on the Hydra Galaxy cluster. This image was obtained with the 1.4-m Japanese telescope at the SAAO (South African Astronomical Observatory) in Sutherland.

The middle picture simulates the effects of the light absorption on the appearance of the same cluster if it were located deep into the Milky Way. Here, the galaxies appear fainter and smaller in size, and also redder, because of the selective extinction effects, which are stronger in the blue filter band and weaker in the red filter band.

The right-hand panel shows how the previous field would appear deep in the ZOA. Light absorption is not the only effect that plagues identification of galaxies behind the Milky Way: there is also an increase in star density. Even when we know the location of the galaxies (as in the left-hand image), it is difficult to identify even the largest and brightest ones in the right-hand image.

Images: T. Nagayama (Ph.D. thesis, University of Nagoya, 2004)

Above: The 1.4-m Japanese telescope at the SAAO in Sutherland.

4 Quest 3(4) 2007

The possibility is not as farfetched as it may seem, and was substantiated by the discovery of a neighbouring galaxy, Dwingeloo 1, in a systematic search for gas-rich galaxies behind the Milky Way with the 25-m Dwingeloo radio telescope in the Netherlands. Subsequent optical observations (from the Isaac Newton Telescope on La Palma, Canary Islands) revealed this previously unknown galaxy.

Were it not located behind the disk of our Milky Way, this magnificent barred spiral galaxy would show up as the eighth brightest in the sky.

Other questions relate to the sizes of the largest groupings of galaxy structures (known as ‘superclusters’). Do their filamentary structures (see the picture above left on p. 3) connect across the ZOA? How large are these superclusters and how did they form? And perhaps most important: What is the nature of what is called the Great Attractor?

Lucky views of the sky The 20% of the sky obscured by our Milky Way seems to hide exciting objects and mass-overdensities.

Is our position particularly unlucky for observers? In fact, it could be much worse.

If we were, for instance, located in our neighbouring Andromeda Galaxy, the obscured part of the sky would not look much different, but our clear view to the nearest galaxy cluster in Virgo would be ‘affected by extinction’ (that is, not visible at all). So our view of the extragalactic sky is in fact quite good.

But we’re unlucky in another way. The Sun has an epicycle motion above and below the Galactic equator. At present, we are elevated only 40 light years (l.y.) above this equator. If our motion were slower – or if we waited another 70 million years – we would be located nearly 300 l.y. above the Galactic equator, which is beyond the thickest layer of obscuration. So, in 70 million years’ time, we will have a better view of the extragalactic sky than we do today.

Deep optical surveys The light of the galaxies (and their size on photographic plates) gradually diminishes the closer they lie to the Galactic equator, where dust obscuration steadily increases. By identifying what appear to be fainter and smaller galaxies, we increasingly pick up galaxies that are intrinsically bright but more and more obscured. Scrutiny of deep photographic plates has, over the last decade, revealed more than 50 000 previously unknown and partly obscured galaxies – close to 20 000 of these by University of Cape Town researchers.

Near-infrared surveys Observing in the infrared makes obscured galaxies easier to find. It has become possible with the advance of large near-infrared CCD (chargecoupled device) detectors in the past five years or so. The 2MASS (2 Micron All Sky Survey), a systematic near-infrared survey of the whole sky in the J, H, and K bands5, became available in 2003.

It was expected to revolutionize ZOA research, and to lay bare the extragalactic sky in the ZOA, given that light absorption is a factor of 10 lower in the K-band than in the optical waveband.

The distribution of the approximately 1.6 million galaxies discovered in this survey gives a superb glimpse of the web-like large-scale structure of galaxies in the nearby Universe (the colours reflect different distance intervals), with filaments and great walls outlining large areas devoid of (luminous) matter.

But expectations that these filaments would also be fully traceable across the ZOA have not 4. A wave is defined as a periodic disturbance in a medium (such as water) or in space. The wavelength is the distance in metres between successive peaks or troughs in a wave. The wavelengths of electromagnetic radiation range from the shorter wavelengths (including gamma- and X-rays) to the longer wavelengths (including infrared and radio).

5. We use specialist glass light filters that allow light to pass only in ‘bands’ of the near-infrared centred on 1.25, 1.65, and 2.15 µm, three terrestrial windows of low atmospheric extinction. They are an extension of the optical colours, which go from ultraviolet (U) to blue (B) to visual (V) to red (R) and then infrared (I). In the past, our detectors could not go beyond the I-band, but when they did (in the 1960s), the letters after “I” (that is, J, H, and K) were used for the longer wavelength bands.

Hidden worlds behind the Milky Way

been entirely fulfilled. While we are now able to see almost all the galaxies in the Galactic Anti-Centre region, the hidden ZOA persists within about 90° of the Galactic Centre. The culprit now is star-crowding, which becomes so severe that the galaxies are completely blocked from our view by foreground stars.

Mid-infrared surveys Moving to even longer wavelengths provides other avenues for ZOA penetration. Observing in the mid-infrared (MIR) became possible with the launch, on 25 August 2003, of the Spitzer Space Telescope with its 0.85-m mirror (Earth’s atmosphere is not transparent to MIR radiation, so observing with the aid of MIR can be done only from space). This MIR imaging and spectroscopy telescope can penetrate thick gas and dust layers, and is sensitive to both elliptical and spiral galaxies.

That this indeed may lead to the discovery of new galaxies has already been confirmed (see picture at top right, and next section).

6. Different gases give off light at different wavelengths, which give them characteristic ‘signatures’. Astronomers observing the line emitted by neutral hydrogen gas are looking at radiation corresponding to a wavelength of 21 cm – that is, corresponding to a spectral line resulting from an atomic transition in neutral (or, un-ionized) hydrogen when the spin of the electron flips between two states, giving out light. Mapping at 21 cm is so good because light at that wavelength passes through almost anything.

Some highlights of discoveries in the ZOA The heart of the Great Attractor During our deep optical decade-long search in the ZOA, which encompassed the overall Great Attractor (GA) region, we recognized – very close to the GA’s predicted centre – the presence of a massive cluster that we called the Norma cluster because of its location in the Norma constellation.

With a mass of a quadrillion (1015) solar masses, it is the nearest to the Milky Way of the massive galaxy clusters in the Universe, and was only recognized as such in 1996, when measurements

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Radio surveys At the longest (radio) wavelengths of the electromagnetic spectrum, gas-rich spiral galaxies – though not the gas-poor elliptical galaxies – can be detected by means of radiation corresponding to the detectable 21-cm line emitted by neutral hydrogen gas6. This observing technique is extremely powerful (as illustrated by the discovery of Dwingeloo 1) because the emitted radiation suffers no absorption by dust particles.

A systematic survey was initiated with the large 64-m Parkes radio telescope in Australia. This instrument has 13 receivers (in an array) in its focus instead of just one, thereby increasing what is visible in the sky at any one time – as well as increasing the survey speed – by a factor of 13.

With this development, extensive systematic sky surveys became a realistic option.

Our recently completed large survey of the southern ZOA with this multibeam receiver resulted in the detection of close to one thousand galaxies through the deepest dust layers of the Galaxy. It proved important in tracking the Great Attractor across the highest dust and star density region of the Milky Way, because, finally, it allowed astronomers to map the galaxy distribution in the optical ZOA.

Top right and top left: The picture at top left is a close-up of part of the picture at top right. Inspection of the Spitzer Legacy Survey “GLIMPSE” (Galactic Legacy Infrared Mid Plane Survey Extraordinaire), which covered the deepest obscuration layers of the Milky Way, has found previously hidden galaxies: the close-up of the lower right-hand part of the GLIMPSE mosaic reveals two spiral galaxies (lying behind an absorption layer of 22 magnitudes in the optical).

Images: Courtesy of Marilyn Meade (UWisconsin) and the GLIMPSE team

Above (middle): Artist’s impression of the Spitzer Space Telescope, operated

by NASA, projected against the Milky Way. Image: Courtesy Spitzer Science Center Above: The Parkes 64-m telescope (in Australia) was important in uncovering galaxies in the ZOA, in mapping the Great Attractor region, and in the discovery of one of the most massive spiral galaxies.

Left: This image, taken with the 2.2-m MPG/ESO telescope at the La Silla Observatory in Chile, shows the central 0.2 x 0.2 degrees of the Norma cluster of galaxies, near the centre of the Great Attractor.

Several bright galaxies and many smaller dwarf ones are visible in this colourful vista.

Quest 3(4) 2007 5

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of the motions of galaxies in the cluster led to the first determination of its mass. Thus far, it is also the most massive cluster in the GA and, in all likelihood, marks its core7.

A galaxy in the act of transformation The high-density Norma cluster, because of its relative proximity to us (and being the nearest galaxy-rich cluster in the Universe), is an excellent laboratory for studying galaxy–galaxy or galaxy–cluster interactions. It’s believed that the evolution of galaxies is significantly altered by such interactions within clusters, since these interactions change the properties of the galaxies (such as colour, gas content, and morphology).

The nearest example of a galaxy undergoing strong transformation is the galaxy WKK 6176, in the Norma cluster. Various other galaxies – even small groups of them – seem to be ‘falling’ into this dense cluster and will be absorbed by it. They also exhibit peculiar morphologies, though none as dramatic as those of WKK 6176.

Top: A detailed view of the galaxy WKK 6176 (before and after star-subtraction). The faint streams (right) show gas stripped from the host galaxy as WKK 6176 moves at high speed through the cluster.

Image: P.A. Woudt (presented at a conference in Sydney, Australia, in July 2007)

Above: Deeper neutral hydrogen radio surveys of the ZOA are among the projects envisioned for MeerKAT, a world-class radio telescope (consisting of an array of 90 telescopes, each 15 m in diameter), currently under construction in the northern Karoo. MeerKAT will be commissioned around 2012 and is a technology demonstrator for the Square Kilometre Array, which South Africa is bidding to host in competition with Australia. (See ”Planning the Karoo Array Telescope” in QUEST, vol. 2, no. 2, pp. 28–29.)

Image: SKA South Africa Project Office

Panel on left: The contours superimposed on these GLIMPSE images – Glimpse G1 (top left) and Glimpse G2 (middle left) – outline the extent of the gas in the disks of these spiral galaxies.

Image: Courtesy Baerbel Koribalski, Australia Telescope National Facility

Lower left: Proposed deep surveys of the Great Attractor Wall footprint are outlined in this zoomedin region area (from the Large-scale Structure map reproduced on p. 4).

The most heavily obscured Great Attractor galaxies ever uncovered Two galaxies discovered in the Spitzer GLIMPSE survey – we refer to them as Glimpse G1 and Glimpse G2 – are located at just the position where we think the Great Attractor extends across the ZOA. All the combined ZOA explorations indicate the GA to be a great wall-like structure with the Norma cluster at its centre. The two galaxies might well form part of the hitherto hidden section of this wall. Baerbel Koribalski, from the Australia Telescope National Facility in Sydney, observed these two galaxies using the Australia Telescope Compact Array, a radio interferometer of 6 radio dishes with 22-m diameters. She confirmed that they are indeed normal star-forming galaxies lying at the distance of the Norma cluster.

This was a fantastic finding – the process uncovered galaxies that are obscured in the optical by about 22 magnitudes (that is, the light we’re able to collect is 300 million times dimmer than the actual inherent brightness of these spiral structures)! The follow-up observations at radio frequencies allowed us to pinpoint the location of the galaxies in 3D space by also measuring the redshift of the 21-cm line emitted by the hydrogen gas in both galaxies.

This has made it possible to map the elusive GA structure – even the parts that we previously thought would forever remain unexplored.

7. Rosalind Skelton, a master’s student in the Department of Astronomy at the University of Cape Town, has been using our near-infrared images of the Norma cluster to measure the distribution of galaxy luminosities (that is, how many there are of particular brightnesses) for a benchmark comparison with more distant galaxy clusters. This will tell us how they evolve with time.

Women in astronomy – explorers of the ZOA The proportion of women working in astronomy is respectable (~20%) compared to their involvement in other areas in natural sciences such as mathematics and physics, though percentages vary dramatically from country to country (from zero to over 50%), and seem uncorrelated – if not anti-correlated – with the financial wealth of countries.

The prevalence of women in the exploration of the ZOA seems astounding, even to me, who has worked in this field for nearly two decades. At times the teams (though small) consisted solely of women, with other collaborative efforts made up of up to 80% of women. The team spirit in such projects has always been great and uplifting, whatever the proportion of women or men – so the message is, let’s all of us, whoever we are, just go for it! – Renée Kraan-Korteweg

6 Quest 3(4) 2007

Hidden worlds behind the Milky Way

It has motivated us to start up a further new survey that might lead to a complete map of the Great Attractor Wall and the mass that invokes such a strong velocity flow field around it.

With our Japanese colleagues Ken Wakamatsu (Gifu University) and Taka Nagayama (Kyoto University), we have begun a deep near-infrared survey using the Infrared Survey Facility at the South African Astronomical Observatory (SAAO)8.

The central, most obscured part of the GA will be investigated during the next cycle of Spitzer Space Telescope observations over the next year, and our hope is to be able to cover the whole footprint (see picture lower left on opposite page). We then plan to survey this same region in the radio with MeerKAT once it is commissioned.

Discovery of one of the most massive spiral galaxies known to date The systematic neutral hydrogen gas radio survey for gas-rich galaxies in the southern ZOA with the Parkes multibeam receiver led unexpectedly to the discovery (by author R.K.K.) of the most massive spiral galaxy known to date, HIZOA J0836-43.

The growth of a spiral galaxy to such a great size is hard to explain with current galaxy formation and evolution models. We therefore decided to explore the surroundings of this galaxy to discover the reason. Did this galaxy grow so fat by gobbling up many satellite dwarf galaxies, or does it lie in a high-density region that promoted growth through a particularly high rate of merging?

Before attempting to investigate the matter further, we verified the facts with deeper and spatially resolved radio observations with the Australia Telescope Compact Array. Deep nearinfrared images were also obtained with the Anglo-Australian Telescope. These data were analysed by Jennifer Donley (then a Fulbright fellow at the Australia Telescope National Facility), who confirmed the excessive mass of this galaxy, which otherwise seems like any other normal spiral star-forming galaxy (see, for instance, those in pictures top left and right on p. 3).

Since it lies in the ZOA and is invisible in the optical (where its light emission is reduced by 10 magnitudes), exploring it is difficult.

The only way forward is to try to probe the surroundings of this mysterious galaxy in the near- and mid-infrared. We have surveyed an area of 1.6° × 1.6° around the massive galaxy in the near-infrared with the 1.4-m telescope at the SAAO. Moreover, we obtained observing time with the (highly competitive) Spitzer Space Telescope to image the immediate environment of this galaxy, including spectroscopy. The latter might clarify whether this galaxy hosts an active galactic nucleus (an indication of recent cannibalistic or merging activities)9.

More to follow The exploration of the ZOA began as an attempt to answer a few specific questions concerning the dynamics in the nearby Universe as best we

Above: A deep near-infrared K-band figure of the massive galaxy (revealing two nearby companions as well) obtained with the Anglo-Australian Telescope. The superimposed contours show the extent of the disk of neutral gas revealed by the Australia Telescope Compact Array.

Image: Courtesy of Donley et al., 2006

Above: The central of the 150 survey fields of 8 x 8 arcminutes obtained with the Infrared Survey Facility at Sutherland to study the environment of the massive spiral galaxy.

could, given the inherent difficulties in mapping that part of the sky and the observing tools at hand. To our delight, the various systematic surveys at different wavebands succeeded in clarifying (and narrowing down) the extent of the ZOA, and gave much-improved answers to unsolved questions.

Also, as is so often the case in research, we were led to unexpected exciting discoveries – discoveries that provided new insights into other astronomical areas and suggested new windows for exploring the ZOA further. This is by no means the end of the ZOA saga – who knows what other secrets the Milky Way is hiding from us? ■ Having worked in countries around the world, Professor Kraan-Korteweg is now head of the Astronomy Department, University of Cape Town.

She is a world leader in surveying and uncovering large-scale structures behind the Milky Way using various observational techniques (optical, near-infrared, and radio). Dr Woudt, her colleague in the same department, is an expert on the Great Attractor and has started using the Southern African Large Telescope in Sutherland to study galaxy transformation processes in distant superclusters.

8. The advantage over the existing 2MASS survey is the increased depth of coverage through longer integration times (600 compared to 7.8 seconds) and improved angular resolution (by a factor of 4).

9. These data were in fact obtained over the period April–June 2007. Their reduction and analysis form the core of Michelle Cluver’s doctoral project in the University of Cape Town’s Astronomy Department (for preliminary results visit http://mensa.ast.uct.ac.za/~michelle).

For details of discoveries described in this article, read the scientific papers. For Dwingeloo 1, read Renée Kraan-Korteweg et al., “Discovery of a nearby spiral galaxy behind the Milky Way”, Nature, vol. 372 (1994), p.77.

Recommended review articles include Renée Kraan-Korteweg, “Cosmological structures behind the Milky Way” in Reviews in Modern Astronomy 18, edited

by S. Röser (New York, Wiley, 2005); and “Galaxies behind the Milky Way and the Great Attractor”, Lectures in Physics, GTO lectures on Astrophysics, edited

by D. Page and J. Hirsch (Heidelberg, Springer, 2000).

For more, visit http://mensa.ast. uct.ac.za/~kraan; the Parkes MultiBeam Research website at www.atnf.csiro. au/research/multibeam/; and the Spitzer Survey of the Great Attractor at http://spider.ipac.caltech.edu/ staff/jarrett/irac/ZoA/. For more on MeerKAT and the Square Kilometre Array, visit www.ska.ac.za.

To revise the basics, visit http://coolcosmos.ipac.caltech. edu/cosmic_classroom/ir_tutorial/ and http://en.wikipedia.org/wiki/ Infrared_astronomy.

Quest 3(4) 2007 7

The state of our Rudi Pretorius introduces South Africa’s newly released National State of the Environment Report.

H Main picture: Aloe tree (Aloe pillansii) in a pristine protected landscape. Image: South African Tourism Above: Aerial view of Cape Town. More than 56% of South Africans live in cities. Image: South African Tourism

8 Quest 3(4) 2007

uman survival, quality of life, cultural diversity, and economic prosperity all depend on the range of goods and services that the environment provides. With more than 56% of South Africans living in urban areas, it is easy to forget how much we depend on our natural resources.

People are having significant effects on the environment. Growing populations are consuming resources and discarding wastes at unprecedented rates. And the ability of the Earth to sustain us is diminished by accelerated

rates of deforestation, soil erosion, and desertification, for instance, and by rising levels of air and water pollution.

Reports guide the way The United Nations Conference on Environment and Development in Rio de Janeiro in 1992 urged nations to issue reports on the environment that would complement traditional fiscal policy statements, budgets, and economic development plans. It also called on governments to transform existing information into forms more useful for decision-making, and to target

information at different groups of users.

Since the Rio Summit, the regular publication of state of the environment reports has been a mechanism used to great effect to make environmental data available to decision-makers and other interested parties – and it is one of the most powerful tools for informing the public. These reports describe the effects of human activities on their surroundings and the implications for people’s health and economic well-being. They also provide the opportunity to monitor the performance of government policies actively, directly, and accountably against actual environmental outcomes. In this way, they can in effect act as report cards on the condition of the environment and our natural resource stocks.

Water – availability and quality South Africa is a semi-arid country, and limited water availability is a key constraint to development. Since 1994, the country’s policy and legal framework for water resources has progressed significantly. Despite numerous improvements, however, many challenges remain.

■ Use of available water resources has been rising, with almost all exploitable sources tapped, resulting in reduced freshwater flows in rivers.

■ Water quality varies, with overall deterioration since the last State of the Environment Report in 1999.

■ The health of river ecosystems is,

1. The first national State of the Environment Report was released in 1999 in response to section 31 of the National Environmental Management Act, which deals with citizens’ rights to access to information on the state of the environment. The Department of Environmental Affairs and Tourism commissioned the second National State of the Environment Report in 2004 and released it in June 2007.

Above left: Nearly 6.5 million people were living in slum housing in South Africa in 2001.

Above (from top): Soil erosion at Loskop. Large areas of South Africa are degraded in this way. Image: Janet Peace Women queueing for water from a tank. In rural areas, many people do not have access to clean piped water.

Image: Lani Holtshauzen, Water Research Commission

Fishing boats in Hout Bay. The fishing industry is vulnerable to the effects of climate change.

Image: Tony van Dalsen, Department of Environmental Affairs and Tourism

on the whole, declining.

■ There are deficits in available water in more than half of the nation’s water management areas, although in theory there is a surplus for the country as a whole.

■ The noteworthy volume of water transfer between water management areas can have adverse ecological effects.

■ By 2025 at the latest, there will be a deficit in available water. ▲ ▲

How does South Africa rate?

State of the environment reporting is well established in South Africa, and several provincial and municipal reports have been published – most of them during the last five years. The second national state of the environment report, South Africa Environment Outlook: A report on the state of the environment1, shows that, overall, South Africa has progressed significantly in the area of environmental management over the past decade.

For example, laws and strategies have been developed that focus on key issues such as biodiversity, air quality, protected areas, urban and rural development, waste, and disaster management, and efforts to implement and enforce policy frameworks have intensified. We have witnessed improving environmental conditions – certain fish stocks have recovered through better management, for instance – and a slowing down of habitat loss in some parts of the country. Budgets have

increased for programmes that at the same time rehabilitate ecosystems and create jobs.

Greater attention has been paid to environmental fiscal reform, cleaner production, energy efficiency, and renewable energy, all of which indicate a growing understanding of the need to manage the country’s natural resources better. More broadly, spending has increased on education, social welfare, and the provision of basic services, and many economic indicators have improved.

Despite such progress, however, recent detailed assessments show that, in general, the condition of the South African environment is deteriorating.

Increasing pollution and declining air quality are harming people’s health.

Natural resources are being exploited in unsustainable ways, which threaten the functioning of ecosystems. Water quality and the health of aquatic ecosystems are matters of concern.

Land degradation remains a serious problem. Some of the important environmental issues discussed in the report are outlined below.

Quest 3(4) 2007 9

Right: A humpback whale breaching. Our tourism industry is built on our natural endowments.

Image: South African Tourism

Opposite page: Trade in medicinal plants is valued at R270 million annually.

Image: Janet Peace

▲

Top: Aerial view of Port Alfred. Coastal development is increasing the pressures on estuaries.

Middle: Invasive Australian black wattle (Acacia mearnsii), which uses excessive water and replaces natural vegetation.

Above: A successful fishing expedition. Dwellers in rural areas depend for their livelihood on the natural resources round them. Images: South African Tourism

10 Quest 3(4) 2007

■ Climate change is predicted to reduce availability of water in South Africa.

Groundwater is important in rural and arid areas, and most of the nine million people supplied with water since 1994 have received it from groundwater resources. Recharge of groundwater is difficult to quantify and makes a precise assessment of available groundwater complicated – in some areas, there has been over-abstraction. The report points out that data are urgently needed on usage and recharge rates, to ensure sustainable use.

Climate change Climate change caused by humans is considered the most significant global environmental issue we face today. South Africa emits more greenhouse gases per person than many industrialized countries, because we depend so heavily on coal for cheap electricity. As much as 92% of our power is generated from burning coal, and emissions will continue to grow with increasing residential electricity demand and greater industrial consumption.

Some of the predictions for climate change in our region over the next 50 years are listed below.

■ There will be less rainfall, especially in the western parts of South Africa, and higher temperatures, particularly in the interior.

■ Changes in the distribution and availability of water will change agricultural patterns.

■ More frequent floods and droughts are likely.

■ As rainfall decreases in the west, the habitats of plants and animals will shift to the eastern parts of the country.

■ The areas that are predicted to dry the most – the Western Cape, Northern Cape, North West, and Limpopo provinces – may suffer increased land degradation, in turn leading to reductions in

agricultural productivity, subsistence livelihoods, and biodiversity.

Sea levels have risen by about 1.2 mm per year over the past three decades. This trend is expected to accelerate in the future, with recent estimates suggesting a 12.3-cm rise by 2020, a 24.5-cm rise by 2050, and a 40.7-cm rise by 2080. Rising sea levels will bring increased coastal erosion, higher levels of saltwater entering estuaries and groundwater, and greater vulnerability to extreme storms.

Human well-being All these changes will profoundly affect human well-being, the economy, and the environment. For example, reduced freshwater flow in rivers will adversely affect estuaries, and bring less dilution of wastewater discharged into rivers. These and other climate-induced changes to our coast will harm the fishing industry, especially for subsistence fishers.

Several of the predicted effects of climate change, such as increased floods and droughts, reduced water availability, and greater land degradation, will make life harder for large numbers of vulnerable South Africans.

Biodiversity and ecosystem functioning Biodiversity is important for the country because it maintains ecosystem functioning, has economic value for tourism, and supports subsistence lifestyles. Healthy ecosystems are the basis of our society and our economy and provide people with vital services: wetlands purify water and control floods; plants remove pollutants from the air and absorb greenhouse gases; soil supports agriculture.

Of all our natural systems, aquatic ecosystems are in worst shape and are experiencing rapid loss of functioning. An estimated 50% of South Africa’s wetlands have been destroyed or converted to other land uses, so they can no longer control

Q Fact file

Environmental facts for South Africa Some estimates

floods, improve water quality, store water, and maintain biodiversity.

The health of our river ecosystems is declining as effluent pollution continues to grow.

The report points out that many of the marine zones on the west coast lack protection and are among the most severely threatened ecosystems in the country. The condition of other coastal and marine systems is good at present, although important data gaps prevent more complete understanding of the status quo. Over-fishing and over-extraction of other organisms (such as perlemoen) are the main threat to marine biodiversity, at all depths and in all regions. Up to 20 species of commercial and recreational marine fish are considered overexploited or collapsed.

South Africa’s estuaries suffer from low levels of protection and are generally in a poor (and declining) state of health. Estuaries around intensively developed areas (Cape southwest coast, Port Elizabeth, and southern KwaZuluNatal) are in the poorest condition.

Terrestrial biodiversity is generally in a better state than that of river and marine ecosystems. But areas of high biodiversity coincide, unfortunately, with areas facing the greatest pressures – namely the southwestern Cape, the central grasslands, and the eastern coastal regions. Widespread land degradation and desertification are causing loss of ecosystem functioning and reducing the productivity of land, with serious consequences for the livelihoods of the rural poor and on the ability of the country to feed its growing population.

An interesting point made in the report is that the rate of spread of alien invasive plants is increasing more rapidly than can be managed through existing programmes for their removal. This causes further loss of biodiversity and reduces riverflow,

which, in turn, reduces aquatic and estuarine biodiversity.

The report also points out that such pressures look set to increase and that South Africa, like the rest of the world, will not reach the Johannesburg Plan of Implementation goal of reducing the rates of biodiversity loss by 2012.

Time for action Throughout the South Africa Environment Outlook report, two very important points are made. First, the environment provides us with the basic natural resources that sustain life, such as clean air, water, and food. Second, the environment is also the basis for economic activity and it sustains our cultural and spiritual needs. Thus a healthy environment is the very foundation for a thriving society and a sustained economy.

Through many case studies and examples, the report shows that ecosystem services are under threat.

With most poorer South Africans directly using natural resources for their survival, we can ill afford to let the environment deteriorate. Poverty reinforces people’s dependence on natural resources and makes them more vulnerable than ever to environmental threats such as polluted water, degraded land, and indoor air pollution.

The message from the national state of the environment report is clear: we need to react responsibly, now, both individually and collectively as a nation.

Unless we act decisively, we risk losing the environmental benefits on which we so heavily rely. ■ Dr Pretorius is Director: Information Management in the Department of Environmental Affairs and Tourism in Pretoria. He initiated the state of environment reporting programme in South Africa in the late 1990s.

For copies of the National State of the Environment Report (available to the public from mid-July 2007 ), contact Wilma Desmore at wdesmore@deat.gov.za. For more information visit www.deat.gov.za. Download individual chapters from http://soer.deat.gov.za.

■ Despite electrification drives, fuel wood is still the main source of energy for about 75% of rural families.

■ More than 2 million tonnes of fertilizer are applied to our soils annually.

■ Although wetlands are essential in an arid, water-scarce country such as ours, about 50% of South Africa’s wetlands have been destroyed; only about 10% of its wetlands are protected; and for about 66% of wetlands there is inadequate information (which seriously impedes our ability to protect and manage this valuable resource).

■ Some 10 000 species of marine plants and animals have been recorded in our marine environment, which is almost 15% of global marine species diversity.

■ Approximately 209 tonnes of carbon is burnt for every US$ equivalent of GDP produced in South Africa (the comparable figure for the USA is 164 tonnes).

■ Sulphur-containing emissions from power stations total about 1.5 million tonnes per year.

■ The carbon dioxide emissions per person in South Africa add up to 7.4 metric tonnes per annum, compared to a global average of some 4 metric tonnes.

Inconvenient truths ■ During 2005, South Africa experienced its hottest mid-year spell in 30 years. Pretoria’s daily average temperature for June and July 2005 were on average 2 °C higher than the average for the past 30 years.

■ Compared with a decade ago, there are 14% more vehicles on our roads, and their emissions contribute to air pollution.

■ Some 70.8% of South Africa’s energy supply in 2000 was provided from coal, and less than 1% of our energy is derived from renewable energy sources.

■ Coal fuels 93% of South Africa’s electricity production. Generating one kilowatt-hour of electricity requires 0.5 kg of coal and 1.29 litres of water, and creates 142 g of ash and 0.9 kg of carbon dioxide.

The global context ■ Sea levels have risen by about 1.2 mm per year over the last three decades. This trend is expected to accelerate in future, with recent estimates suggesting a 12.3-cm rise by 2020, and a 40.7-cm rise by 2080.

■ Climate change has the potential to reduce the availability of water significantly in South Africa by altering hydrological systems and water resources in the entire region.

■ One of the predicted effects of climate change is that the area of South Africa under threat from malaria could more than double in the next 50 years. Over 7.8 million people could be at risk of contracting the disease, of whom 5.2 million did not previously live in areas where malaria was a problem.

■ Invasive alien plants have spread over 10 million ha of South Africa – more than 750 tree species and 8 000 herbaceous species have been introduced.

■ Despite the fact that biodiversity benefits many people, at least 60% of the ecosystem health and services that have been measured are declining rapidly worldwide, because of invasion by alien species and changes in land-use, climate, and other direct drivers of environmental alteration.

■ South Africa is party to almost 100 different multilateral environmental agreements.

Quest 3(4) 2007 11

Knowing how small animals survive in their estuarine homes tells us a lot about the health of South Africa’s coastline and what’s needed to save our fishing industry for future generations.

The ways that fishes have adapted to changing environments can give useful information when people have to decide how best to conserve threatened species and keep ecosystems healthy, writes Monica Mwale.

P

ipefishes are small, tubular fishes that belong to the Syngnathidae family – as does the popular seahorse. Though they may at first sight seem unremarkable, they are puzzling and interesting for two main reasons.

First, individuals can look so different from one another that it’s sometimes hard to tell exactly which species they belong to. Second, their lifestyle and the extraordinary way in which they reproduce make them vulnerable to environmental changes. This means that they can be useful indicators when we are monitoring the effects of human activities on biodiversity in the dramatically transforming estuarine and coastal shoreline areas where they live.

Gender role reversal The most diverse genus in the family is Syngnathus, with 32 described species.

They are mainly found in the Atlantic and Eastern Pacific oceans and are rare in the Indo-West Pacific. The two species that are endemic to southern African coastal and estuarine waters – the long snout pipefish, Syngnathus

The full brood pouch of a pregnant long snout pipefish male (Syngnathus temminckii).

12 Quest 3(4) 2007

temminckii, and the estuarine pipefish (also known less accurately as the river pipefish), S. watermeyeri – are not well understood. (In fact, the taxonomic status of most species of this genus is unclear.)

We do know, however, that their unusual and complicated family life makes our pipefish vulnerable to changes in their surroundings. Like seahorses, they are uniquely different from most organisms, in that males rather than females take responsibility for bearing and rearing their young.

Here’s what happens. The male receives eggs from a female and carries them on his body surface or inside a specialized brood pouch under his trunk or tail. This ‘pregnant’ male fertilizes the eggs, provides nutrition and oxygen to the developing embryos for up to a month, and gives birth to live young. Paternal care and investment in reproduction is therefore substantial, while maternal care is slight or even nonexistent, as all the females do is provide the eggs. Thus the usual sex roles are reversed, and the females compete with one another in mating rituals. In the case of Syngnathus typhle, for example, pregnant females display themselves vigorously by swimming up and down well above the seagrass beds, often in temporary groups, while the males typically swim within the eelgrass,

from which position they select the most suitable mate.

As a result, females have a higher potential reproductive rate than males – they produce more eggs than the males can brood during an equivalent period of time, and they can contribute eggs to more than one male. The males, on the other hand, are more choosey in selecting females (to ensure reproductive success), as the length of their brooding cycle or ‘pregnancy’ limits the number of times they can mate.

The relatively low fecundity and long period of parental care makes pipefish vulnerable when their habitat is disturbed, and the greatest threat to their survival comes from the activities of people.

Identifying the South African species Of the two species of pipefish endemic to our region, S. temminckii is the most widely distributed. It’s found in most estuaries, and in the coastal areas from KwaZulu-Natal in the Tugela system up to Walvis Bay in Namibia.

Syngnathus watermeyeri is rarer, with a restricted distribution in the East and West Kleinemonde estuaries.

It is listed as critically endangered1 (CR-B1+2abd) on the IUCN Red List (2002), as it is now limited to the East and West Kleinemonde estuaries

1. CR-B1+2abd means a taxon is ‘critically endangered’ when it faces an extremely high risk of extinction in the wild in the immediate future. The extent of its occurrence is estimated to be less than 100 km2 or its area of occupancy is estimated to be less than 10 km2. These estimates indicate that the species is severely fragmented or is known to exist at only a single location. Continuing decline is observed, inferred, or projected, based on occurrence, area of occupancy, and the number of locations or subpopulations. For more, visit www.iucnredlist.org/info/categories_criteria1994#categories

Left: Researchers trying to save and collect stranded endangered pipefishes in the East Kleinemonde river basin drained of water in August 2001 by artificial breaching to protect housing built below the flood line. About 50% of the biomass (vegetative macrophytes, fishes, and invertebrates) was exposed and died. Most estuarine systems are now artificially opened by breaching because local developments have altered the freshwater flow patterns into these systems, thus affecting their natural opening and closing dynamics. Estuaries are artificially breached by means of a channel dug across the sand barrier (berm) to a level below the water level in the impoundment. Artificial breaching can make water levels drop from 2.8 m above sea level to 0.2 m below sea level in just a few hours, creating large and rapid changes in the physico-chemical environment, which, in turn, trigger major biological responses and damage fishes and other life.

Distribution of Syngnathus watermeyeri in the East and West Kleinemonde estuaries (1 and 2) of South Africa, showing the other estuaries where it was previously recorded: Kasouga (3), Kariega (4), and Bushmans (5).

Defining species and their evolution

Long snout pipefish (Syngnathus temminckii).

Estuarine pipefish (Syngnathus watermeyeri).

Left: Variations in lateral trunk ridge lines. Such characteristics vary greatly in some pipefish species. Several (such as Syngnathus acus, S. leptorhynchus, and S. schlegeli) are hard to distinguish because of similar general morphology and fin-ray and body-ring counts.

and seems to have disappeared from adjacent Eastern Cape estuaries (Kasouga and Bushmans2) where it was previously recorded.

Although the genus Syngnathus is widely known, the species of pipefish are not always easy to distinguish from one another, as they vary in their form and structure (morphology) and have few unique characteristics. This can make species descriptions and identification keys difficult to establish.

Such identification problems also exist with the South African endemic species. Syngnathus temminckii was originally described as a synonym for the European S. acus species, so this needed revision. Also, taxonomists depending on traditional ways to identify fish species according to their morphology have been uncertain about including S. watermeyeri in the same genus, as it has a shorter snout and fewer pectoral fin rays (6–8 as distinct from 10–14) than the others.

So we had to use other means to

discover where this species belongs.

My work used genetic and biological data to study the phylogenetic3 relationships of our local species within Syngnathus, as well as their similarities and evolutionary relationships. Is S. temminckii distinct as a species from European populations of S. acus ?

How is it related to the very different S. watermeyeri? To find the answers, we selected a molecular approach, which has proved helpful over the past 40 years for understanding species diversity.

Pipefish typically inhabit low-lying coastal areas and estuaries, which are extremely vulnerable to sea-level rise and marine incursion, and have been affected by historical climatic events.

The two South African species are geographically separated from the other species in the genus found elsewhere in the world, so it was possible that they represented a unique group that had been isolated and that had diverged from other Syngnathus lineages.

Our study found that S. temminckii and S. watermeyeri are in fact sister-taxa and share a recent common ancestor, and this supported the inclusion of S. watermeyeri in Syngnathus. We also discovered that that South African S. temminckii differs genetically as well as morphologically from European populations of S. acus, which shows ▲ ▲

2. In an intensive ichthyofaunal survey in early November 2006, a breeding population of estuarine pipefish was discovered in the middle and upper reaches of the Kariega Estuary (that is, between the Bushmans and Kasouga estuaries) after an absence of more than four decades. It is suggested that the unexpected presence of the fish in the area resulted from heavy rainfall that had created optimal habitat conditions. For details, read P.D. Vorwerk, P.W. Froneman, and A.W. Paterson, “Recovery of the critically endangered river pipefish, Syngnathus watermeyeri, in the Kariega Estuary, Eastern Cape province”, South African Journal of Science, vol. 104 (MONTH 2007).

3. Phylogenetics is the field of biology that deals with the study of relationships between organisms, and aims to show their evolutionary history.

Morphology – the study of the form and structure of organisms, especially their external form. Morphology traditionally offers taxonomists a way of determining what particular features distinguish one species from another.

Molecular approach – a molecular marker is any site (locus) in the genome of an organism at which the DNA base sequence varies among the different individuals of a population; it can be determined through biochemical analysis of the DNA. Molecular markers can be used to identify unique population groups and to point to relationships among organisms whose morphology, behaviour, or biochemistry does not offer enough of the right kind of information.

Genetic structure – the genetic structure of species can reveal a great deal about the history of past interactions (that is, gene flow) within and among their subdivisions and populations. Genetic variability, therefore, represents adaptations that have evolved as a species adjusted to changing conditions over time in order to survive, and can be crucial to the survival of the particular gene pool.

Genetic divergence and speciation – changing environment conditions can (a) force species to move and establish themselves in new habitats, and also (b) restrict movement among individuals and become a barrier to dispersal. These effects on gene flow can result in genetic divergence or even speciation (that is, the development of one or more new species from an existing species). Understanding the historical relationships helps us to know better the processes and conditions that affect organisms, and to make better management decisions for conserving specific animals as well as entire ecosystems.

For example, past historical geological changes and environmental variables such as sea-level fluctuations, ocean currents, temperature, habitats, and food availability have influenced the present distribution of species on southern Africa’s coastline. The pipefish genus Syngnathus has successfully responded to such changes and achieved wide geographic distributions, possibly through isolation by distance.

Quest 3(4) 2007 13

A dead stranded pipefish found by researchers hours after the East Kleinemonde river basin was exposed after artificial breaching in August 2001. ▲

that these two species have been geographically and reproductively isolated for long enough to have diverged genetically from one another.

Keeping an eye on our pipefish Now that we know how to identify our South African pipefish species, we can recognize them wherever they’re found, and understand more clearly what kind of environmental deterioration endangers their continued survival in a particular area. Their presence can help us to determine and monitor the health of a piece of coastline or an estuary: reduced pipefish numbers could be a warning. If their numbers fall, we need to sound the alarm.

Pipefish are adversely affected by environmental changes because of their

restricted distributions, low mobility, small home ranges, and relatively low and slow reproduction rate. Habitat loss or alteration, therefore, seriously threatens their survival – and the gravest threat comes from people.

Accelerated coastal development over the last 10–15 years has so disturbed and altered South Africa’s coastal and estuarine habitats that it has put our pipefish species seriously at risk. Development projects such as reservoir construction, and surface water diversion, have reduced the freshwater flow into estuaries and increased the incoming silt. Most of the water flow is now controlled artificially, and has altered the natural timing of opening and closure of estuaries to the marine environment. The construction of housing and jetties on estuarine banks has reduced the distribution and abundance of reed-bed (seagrass) habitats that are critical for pipefish as nursery areas, feeding grounds, and shelter from predators.

The information that this study has generated is essential for understanding and conserving our endemic pipefish species. Although they may live in various habitats and have a moderately large geographical range, their

complex life history and reproductive strategies make them highly vulnerable when their environments alter. The results of this study could help us to conserve these threatened fishes – and to understand better the effects of human development on biodiversity in our country’s estuaries and coastal environments. The very susceptibility of our pipefishes makes them able to send out clear and timely warning of the effects of the profound changes that are taking place.

Dr Mwale is an aquatic biologist at the South African Institute for Aquatic Biodiversity. Her research on the systematics of marine fishes focuses on the use of DNA sequence and morphological data to clarify phylogenetic relationships. She currently runs a barcoding project on fishes of the Western Indian Ocean (details in Quest vol. 3, no. 2, pp. 10–11).

For more, consult these publications: A. Berglund, “Risky sex: male pipefishes mate at random in the presence of a predator”, Animal Behaviour, vol. 46 (1993), pp.169–175; A. Berglund and I. Ahnesjö, “Sex-role reversal in pipefish”, Advances in the Study of Behavior, vol. 32 (2003), pp.131–167; C.E. Dawson, Indo-Pacific pipefishes (Red Sea to the Americas), (The Gulf Coast Research Laboratory, Ocean Springs, Mississippi, 1985); P.Z. Goldstein et al., “Conservation genetics at the species boundary”, Conservation Biology, vol.14 (2000), pp.120–131.

Nikki James demonstrates how marine fish larvae use smell to guide them to the estuarine nursery areas where they can safely grow to adulthood.

L

ife for many marine fishes starts out in the open sea, where they are spawned. Then, as larvae, they move to safer nearshore areas, and after that, in their late larval stage or as early juveniles, they locate the mouths of estuaries and move upstream to nursery areas in a process called ‘recruitment’. There they grow for up to three years in rich murky waters that offer abundant food and protection from predators, after which they return to the sea.

How do these larvae – some as small as 9 mm and just two or three months old – find their estuarine nurseries?

Could these tiny animals be attracted to the right place by the speed of the current, or salinity, or temperature, or turbidity (murkiness), or smell?

Many studies have pointed to the significance of olfactory (smell) cues.

Chemical signals are important in the spawning of many fish species. We also know that European eels migrating to fresh water are attracted to odours given

14 Quest 3(4) 2007

3

2

1 Map of the Kowie River, Port Alfred, showing locations of water collection points for seawater (1), estuary water (2), and river water (3).

out by organic components in coastal rivers, and that salmon use smell when they migrate back home to spawn in the streams where they were born.

Could olfaction also help marine larvae and early juveniles find their way into estuaries? Fieldwork in South Africa has suggested this possibility (supported

by Australian research showing that coral reef fish larvae are attracted to odour), but the theory needed to be tested.

The idea was that land-based odours could persist in waters entering the sea, much as land-based fine sediments discolour seawater. To check if larvae pick up and follow such smells, we observed late-stage Cape stumpnose larvae (Family Sparidae) and the choices they made.

We selected this fish because it’s endemic to southern Africa, depends entirely on estuaries as nursery areas for 1–2 years, and is one of the most abundant marine species found in warm-temperate estuaries. Other species using estuaries as kindergartens may behave similarly, so the findings could help us to understand them too, and discover ways to maintain their populations. Coastal and estuarine anglers in the Cape fish for estuarinedependent white steenbras, for example, which are in serious decline, with the catch rate of recreational shore anglers down by 90% since the mid-1970s.

So we needed more facts about the early life of such fishes.

Choices for survival In spring 2004, we conducted experiments in Port Alfred at the Rhodes University Marine Laboratory on the banks of the permanently open Kowie Estuary. Using a fine-meshed hand-net, we collected 37 late-stage Rhabdosargus holubi larvae, 13–15 mm long, from the lower reaches of the estuary, and split them into three groups. To determine what water type the larvae liked best, our experiments allowed them a choice of two: (1) estuary water and seawater, (2) river water and seawater, and (3) river water and estuary water1. All the types of water were adjusted to the same salinity and maintained at the same temperature, to make odour the deciding factor.

We found that our larvae clearly preferred estuary and river water over the plain seawater we used as a control – that is, they had a 75% preference for estuary water over seawater, and a 71% preference for river water over seawater. This result showed us that odour could be what guides these larvae into estuaries.

They showed no clear preference for river water over estuary water (their preferences averaged 58% and 41%, respectively), which told us that they liked the smell of both water types.

So what?

For the first time we’ve demonstrated that larvae of marine fish species using estuaries as nurseries find and follow the smell of both river and estuary water. The results also suggest that recruitment might succeed better when both estuarine and river water is allowed to enter the sea, as our larvae were attracted to olfactory cues from both the estuary and the river water.

All this has wider implications.

South Africa’s need for water has caused numerous dams to be built in the catchment areas of many of

our rivers, preventing fresh water from reaching estuaries. So fewer larvae and early juveniles may be able to find the estuarine nursery areas they need, which, in turn, could significantly reduce the catch of fisheries relying on estuary-associated species, such as white steenbras.

The more we learn – and the more sensibly we apply research findings such as these – the better we can protect and grow our precious fish stocks for future generations. ■ Dr James is at the new South African Environmental Observation Network (SAEON) Elwandle Node hosted by the South African Institute for Aquatic Biodiversity in Grahamstown. Her recently completed doctorate focused on fish community structure and recruitment in a warm-temperate estuary.

1. River water for the experiments was collected just below the confluence of the Kowie and Lushington Rivers, about 31 km above the head of the Kowie Estuary; estuary water came from the lower reaches of the Kowie Estuary, 5.2 km upstream of the mouth during the latter part of the ebb tide; and seawater was collected about 6 km out to sea from the Kowie Estuary where there is little or no estuarine influence. Water was stored at ambient conditions for some three days before use, to reduce temperature differences. Before each experiment, the estuarine and river water was adjusted to a salinity of 35% (the salinity of seawater) to eliminate salinity as an influence.

Above and left: Preference of Cape stumpnose larvae for different water types, based on smell, was tested in a choice chamber (above), where animals could choose between two types. Water from two different sources (for example, seawater and river water) were delivered at constant speed into the adjacent sides of the upstream end of the choice chamber.

Each flowed through stacked drinking straws, which smooth the flow of water creating laminar flow, to ensure that the water types remained separated in the test area (top left) despite the absence of a physical partition. The separation of the two water types before salinity-adjustment mixing in the choice chamber (middle left) and as they flowed through the test area (top left) was checked using food dye.

As each experiment began, the chambers were filled with water from the larval holding tank. Then 5-9 larvae were introduced into the test area. After 5 minutes for them to acclimatize at no-flow (below left), test water was sent through the adjacent sides of the test chamber for 3 minutes. To quantify larval movement, researchers counted the number of individuals in each side of the test area in the last minute of each experiment, and changes during this minute were recorded. Each experiment was repeated three times.

For more scientific details, read J. Atema et al., “ Larval fish could use odour for detection, retention and orientation to reefs”, Marine Ecology Progress Series 241 (2002), pp.151–160; B.A. Bennett, “The fishery for white steenbras Lithognathus lithognathus off the Cape Coast, South Africa, with some considerations for its management”, South African Journal of Marine Science, vol. 13 (1993), pp.1–14; P.D. Cowley et al., “The surf-zone ichthyoplankton adjacent to an intermittently open estuary, with evidence of recruitment during marine overwash events”, Estuarine, Coastal and Shelf Science, vol. 52 (2001), pp.339–348; N.A. Strydom, “Occurrence of larval and early juvenile fishes in the surf zone adjacent to two intermittently open estuaries, South Africa”, Environmental Biology of Fishes, vol. 66 (2003), pp.349–359; A.K. Whitfield, “Abundance of larval and 0+ juvenile marine fishes in the lower reaches of three southern African estuaries with differing freshwater inputs”, Marine Ecology Progress Series 105 (1994), pp.257–267; and J. Atema, “Smelling and tasting underwater”, Oceanus, vol. 23(3) (1980), pp.4–18. You can also visit http://zebra.sc.edu/smell/nitin/nitin for N. Patel, “Investigations into how salmon find their home stream” (2007); and www.livescience.com/animals/070110_scent_trail for J. Bryner, “In a vast sea, how fish find home” (2007).

Serving Africa's needs in understanding fishes and aquatic environments Situated in Grahamstown in the Eastern Cape, SAIAB is an internationally recognized centre for the study of aquatic biodiversity, serving the nation through the generation, dissemination and application of knowledge to understanding and solving problems on the conservation and wise use of African fishes and aquatic biodiversity.

Research in the institute is directed at marine and freshwater fish taxonomy, systematics, genetics, biology, ecology, ethology, conservation, management and environmental issues.

SAIAB houses world-famous collections of marine fishes from the Atlantic, Indo-Pacific and Antarctic Oceans, as well as freshwater fishes from Africa and adjacent islands. Its collections are national assets that are held in perpetuity for the benefit of science and future generations. The collections include biological specimens, genetic samples, photographic images, original scientific illustration artwork, spatial data and publications. It is an information hub for African fish, fisheries and aquaculture.

Contact us: Private Bag 1015, Grahamstown, 6140, Tel +27 (0)46 6035800, Fax +27 (0)46 6222403, email saiab@ru.ac.za, web http://www.saiab.ru.ac.za © SAIAB 2007. Illustrations by Elaine Heemstra and Dave Voorveldt. Layout by Magriet Cruywagen

Quest 3(4) 2007 15

Science, technology and innovation play a crucial role in the improvement of the quality of life in South Africa. Collectively the fields increase industry’s competitiveness thereby enhancing the prosperity of the country and the rest of the African Continent.

We at the National Research Foundation (founded on 1 April 1999) are dedicated to respond to national and continental developmental needs. Our vision enshrines a prosperous South Africa and an African continent steeped in a knowledge culture, free of widespread diseases and poverty.

We aim to achieve these objectives through: • The support and promotion of research through funding.

• Human resource development, and the • Provision of the necessary research facilities in order to facilitate the creation of knowledge, innovation and development in all fields of science and technology, and indigenous knowledge.

The NRF consists of following business units: • South African Agency for Science and Technology Advancement (SAATSA) - Pretoria • Research and Innovation Support Agency (RISA) - Pretoria • Hartebeesthoek Radio Astronomy Observatory (HartROA) - Krugersdorp • Hermanus Magnetic Observatory (HMO) - Hermanus • iThemba Laboratory for Accelerator Based Sciences (iThemba LABS) - Somerset West • South African Institute for Aquatic Biodiversity (SAIAB) - Grahamstown • National Zoological Gardens of South Africa (NZG) - Pretoria • South African Environmental Observation Network (SAEON) - Pretoria • South African Astronomical Observatory (SAAO) - Cape Town Major current and future activities: Southern African Large Telescope (SALT), the largest telescope in the southern hemisphere. The NRF is also managing the research component of the South African Environmental Observation Network in Pretoria (SAEON) - Pretoria.

The NRF’s facilities are clustered as follows.

Astro/Space/Geosciences • South African Astronomical Observatory (SAAO), also responsible for SALT. • Hartebeesthoek Radio Astronomy Observatory (HartROA); and • Hermanus Magnetic Observatory (HMO).

Biodiversity/Conservation • South African Institute for Aquatic Biodiversity (SAIAB).

• South African Environmental Observation Network.

• The National Zoological Gardens.

Nuclear Sciences • iThemba Laboratory for Accelerator Based Sciences.

BA 2620/NRF

Visit our website at: http://www.nrf.ac.za or contact 012 481-4000/4001

16 Quest 3(4) 2007

View from the Arabella Grand Sheraton Hotel, showing a prominent layer of polluted air extending across Cape Town harbour. The layer is confined to the lower atmosphere by a temperature inversion. (A temperature inversion arises when a relatively stable layer of warm air traps a cooler layer below it.)

What’s that brown haze over Cape Town?

Patience Gwaze reports on the nature of the brown haze that so often hangs over areas of the Cape Peninsula in the winter months from May to August.

T

are particles, carbon monoxide, sulphur dioxide (SO2), oxides of nitrogen (NOx), volatile organic compounds (VOCs), and ozone – all of which are unhealthy.

Examining the gunk One way to understand a pollution phenomenon such as brown haze is to conduct an emission inventory – that is, a quantified list of emission estimates for sources of air pollution in a given area for a specified time period. One of the first comprehensive studies of the Cape Town brown haze (CTBH I) was conducted by Mark Wicking-Baird and his colleagues in 1997. They complied an emissions inventory for the Cape Town metropolitan area for PM2.5 (atmospheric particles with diameter less than 2.5 µm), PM10 (particles with diameters between 2.5 µm and 10 µm), NOx, SO2, and VOCs. They found that emissions from both diesel and petrol vehicles contributed as much as 67% of the PM2.5 emissions, and domestic wood-burning contributed 14%. PM2.5 particulate levels were comparable to those measured in heavily polluted cities globally.

To understand the brown haze better, an airborne experiment called the “Cape Town Brown Haze II” (CTBH II) campaign examined the atmosphere over Cape Town during intense haze periods in July and August 2003. The overall objectives were to determine the microphysical, chemical, and optical properties of the haze, and the type and spatial distribution of particles; to describe the distribution and the contributions of trace gas emissions

to haze formation; to identify the importance of the contribution of VOCs to the local atmosphere; and to understand the possible effects of the haze on people’s health in general.

Among the most interesting results of this study were the particle measurements and the findings and observations from five flights conducted during intense haze episodes on 6, 7, 15, 22, and 23 August 2003.

Haze formation During the winter months between May and August, Cape Town suffers from episodes of poor visibility associated with brown haze, which is attributed to high concentrations of highly light-absorbing soot particles (as distinct from photochemically produced ‘white haze’ that is composed of light-scattering particles).

Typically, the brown haze appears in stable meteorological conditions when there is a shallow mixed layer of air with a capping temperature inversion (see picture caption above).

The inversion acts as a lid, dampening vertical air movements and thereby trapping air pollutants within the boundary layer (that is, under the ‘lid’).

In addition, the complex topography around Cape Town makes ventilation impossible and prevents air pollutants from being dispersed or diluted.

All these conditions allow local air pollution to accumulate in the boundary layer of the atmosphere (that is, the layer 0–2 km above ground) and, at high concentrations, pollutants impair visibility by scattering and absorbing ▲ ▲

he harbour city of Cape Town is home to just over 3.4 million people. With other city centres and industrial sites in South Africa, including South Durban, Johannesburg, and the Vaal Triangle, Cape Town has become a priority for environmental attention because of persistent high levels of anthropogenic air pollution (that is, pollution caused mainly by people). These are a cause for public concern because at times they exceed levels stipulated for human health, putting everyone at risk, especially children and the elderly.

Problems of air quality are not new to Cape Town. In the 1960s, it suffered thick smog from the extensive use of coal in locomotives, industries, and private homes. The City Council successfully reduced pollution by ending the use of coal-burning locomotives and closing down the coalpowered stations. But since the 1980s, a new form of smog has emerged called ‘brown haze’ because of its colour. It is an anthropogenic urban air pollution phenomenon that affects cities worldwide including Beijing, Auckland, and Los Angeles.

Cape Town’s main sources of air pollution are industries, motor vehicles (petrol and diesel engine emissions, dust rising up from paved and unpaved roads, and the effects of brakes and tyre wear), emissions from domestic fuel burning for cooking and indoor heating, and biogenic emissions (that is, emissions from natural sources such as plants and trees). The main pollutants

Quest 3(4) 2007 17

Above: Location of Cape Town and surrounding areas. ▲

light. This diminishes horizontal visibility and gives a characteristically hazy appearance to everything one sees. Earlier studies showed that haze episodes are confined to discrete peaks.

In other words, a period of haze-free weather will suddenly be followed by some 3–5 days of haze before the air is cleansed of pollution either by strong north-westerly winds or spells of rain.

Brown haze occurs mainly over the Cape Flats, a plain to the east of Cape Town’s Central Business District (CBD) and north of False Bay, covered by formal and informal residential areas, manufacturing industries, the city’s international airport, and major roads. Depending on the strength and direction of winds, the haze may drift southwards over False Bay or eastwards, where it is blocked by the mountains east of the city. The haze is therefore a local urban rather than a regional phenomenon.

Not only is it bad for human health, but the haze also creates a visual blot over the city that prides itself on its world-class tourism status.

Cape Town Brown Haze Study II The CTBH II was conducted over the metropolis, using state-of-the-art measurement techniques on board

the South African Weather Service’s Aerocommander 690A ZS-JRB aircraft in 20031. Samples were collected by flying the plane through the haze and trapping airborne particles on polycarbonate filters from air passing through equipment mounted on the aircraft wingtips.

The collected samples were analysed with a high-resolution microscope – a scanning electron microscope (SEM) – using a technique known as ‘single particle analysis’ to establish the morphology (shape and size), chemical composition, and size distribution of individual particles.

Particle morphologies yield important information about where the pollutants come from, their chemical composition, and even the history of their life in the atmosphere. A total of 6 704 particles were identified in the SEM analyses.

Particles were categorized according to shape into seven groups, including aggregated soot particles, sulphates (SO42-), mineral dust, sea-salt, and tar balls/fly ash.

Soot particles were the most prevalent type in the boundary layer, Mitchells Plain–Belhar Gordon’s Bay Cape Point

Above: Vertical profile of particles over Mitchells Plain–Belhar, Cape Point, and Gordon’s Bay. They indicate the distributions of particle number concentrations from the near surface to about 1 800 m above sea level in the atmosphere.

1. Particle-number concentrations (measured in particles per cubic centimetre) and trace gases measurements were made online during flights. In addition, particles were collected on board using an Air Borne Streaker (ABS) aerosol sampling technique. In this technique, particles are collected on a filter by catching air through a device on the aircraft wing. The filter is fixed on a frame that is rotated by a stepping motor to collect particles from particular geographic locations and times as the aircraft flies.

18 Quest 3(4) 2007

with high concentrations of 12–46% indicating that combustion – be it from diesel engines, or industrial or domestic sources – contribute significantly to Cape Town’s haze. As expected, locations with high traffic densities such as the CBD, and low-earning socioeconomic suburbs such as Khayelitsha, showed the highest soot concentrations emitted largely by vehicles and by fires lit for domestic purposes.

The spatial distribution of particle matter within the haze depended partly on the stability of the atmosphere (that is, on the characteristics of the boundary layer as defined by thermal variations), and on the way in which the boundary layer changed during the course of the day. It also depended on the sources of the particles, and the transportation of air by winds. In the mornings (07:00–11:30), for instance, high particle-number concentrations (up to 10 000 cm-3) were confined to the part of the haze below 400 m above sea level, due to accumulated overnight and morning domestic combustion emissions as well as vehicle emissions during the early rush hours. In the late morning to afternoon, the boundary layer became three times thicker, extending to 1 300 m above sea level.

The vertical distribution of particles showed great variation in particlenumber concentrations from one location to another, indicating very different source strengths and transportation patterns of particles (see graph).

The cleanest air and lowest particle concentrations were at Cape Point, where there are no local sources of pollution, and on the day in question no dirty air masses had been transported there from the city. The Gordon’s Bay profile was sampled downwind of the city centre, and the air was contaminated by emissions from the urban conglomeration of Cape Town, unlike the situation at Cape Point. On average, the Cape Point concentrations were up to 20 times weaker than those in the polluted air. These differences show the remarkable contrast between the pristine marine atmosphere at Cape Point and the influence of Cape Town’s pollution downwind of the city.

We also found that the higher the altitude, the lower were the particle concentrations. This implies that particles were emitted locally and at low elevations. The high particle-number concentrations in the boundary layer are consistent with polluted urban environments. The sudden reduction in concentrations around 1 300 m above sea level is because the persistent temperature inversion at the top of the boundary layer traps and caps the pollutants, preventing them from being transported above 1 300 m. The inversion also serves to separate the polluted boundary layer adjacent to the ground from the clean troposphere above, and creates the distinctive horizontal layer of pollution that we can see so clearly.

Solutions coming up Emissions from transport and from industrial and domestic combustion are the main sources of Cape Town’s brown-haze particulate matter. The high concentration of soot (carbon) particles affects the way in which the haze interacts with sunlight, and causes the characteristic colour of the brown haze.

The effects of the Mother City’s air pollution extend beyond the obvious ugliness of the brown haze, however.

It has the potential to bring regional climate change, for instance. And in big cities around the world, exposure to fine particulate matter that comes from burning is recognized as a grave threat to human health, as, amongst other things, it causes respiratory diseases that include pneumonia and influenza.

Although Cape Town and its surroundings is a small area compared to global mega-cities, its location provides excellent scientific opportunities for broadening our studies of the influence of a plume of urban pollution on the clean background of marine air and on the region’s climate.

In 1997, Wicking-Baird and his group projected an increase in anthropogenic emissions in Cape Town. For a ‘business as usual’ scenario, they estimated that PM2.5 emissions would increase by 48% between 1997 and 2007 as a result of increasing population, the growing size and age of the city’s vehicle fleet, and economic expansion.

Opposite page top (left and middle): Scanning electron microscope pictures of soot particles typically found in wood and diesel smoke. These particles show the distinct structures of agglomerated small spheroids that form either compact particles or branched/chained particles.

Opposite page top (right): A scanning electron microscope picture of an euhedral fresh sea-salt particle.

Dangerous particles Our results show that most of the particles in the haze over Cape Town are fine particulate (PM2.5), which arise from combustion. They are a health hazard. Studies have shown that longterm exposure to fine particulate matter from diesel exhausts, for instance, increases the risk of lung cancer and cardiopulmonary mortality. The fine particulate matter in the nanoscale range can be inhaled deep into the pulmonary (lung) system, where it may pass from lungs into the bloodstream, vital organs, or the brain by means of sensory nerve endings. (Examples of the link between air pollution episodes and mortality rates include reports on fog that affected people along the Meuse Valley, Belgium, in December 1930, and the ‘lethal London fog’ or ‘pea-soupers’ of 1952.)

To meet these challenges, the City of Cape Town has put forward a comprehensive, multidisciplinary Air Quality Management Plan to monitor and improve air quality and to enforce air quality legislation, amongst other things. Only in this way can brown haze episodes over Cape Town be brought under control and stop damaging the beauty of the place and the health of the people who live, work, and visit there. ■ Dr Gwaze is a post-doctoral fellow at the University of Johannesburg in the Department of Geography, Environmental Management and Energy Studies. She conducts aerosol research and investigates air pollution characteristics from domestic coal combustion emissions2.

This page top (left and middle): Scanning electron microscope pictures of typical mineral dust particles. On the left, agglomerate of mineral dust particles with complex composition of Na, Si, Ca, Fe, Zn, and Mn and traces of S, Mg, and Al; on the right, an iron silicate dust particle.

Lower left: Scanning electron microscope picture of a hollow spherical particle typically found only in low grade coal smoke.

Top right: This large, nearly spherical particle was classified as fly-ash.

For research results on Cape Town’s brown haze, consult M.C. Wicking-Baird et al., Cape Town Brown Haze Study, Report No. Gen 182 (Cape Town: Energy Research Institute, University of Cape Town, 1997), and P. Gwaze et al., “Physical, chemical, and optical properties of aerosol particles collected over Cape Town during winter haze episodes”, South African Journal of Science, vol. 103 (2007), pp.35–43. For more on soot particles, read P. Gwaze et al.“Comparison of three methods of fractal analysis applied to soot aggregates from wood combustion”, Journal of Aerosol Science, vol. 37 (2006), pp.820–838 (doi:810.1016/j.jaerosci.2005.1006.1007).

2. Dr Gwaze’s study was supported through a scholarship from the Max-Planck-Gesellschaft and a fellowship from the National Research Foundation, with additional help from the University of Johannesburg. Aerosol measurements in the Cape Town Brown Haze Project II were conducted together with the Climatology Research Group of the University of the Witwatersrand, using the Aerocommander 690 of the South African Weather Service, and the project was funded by the South African Petroleum Industries Association and Cape Town Metro.

Quest 3(4) 2007 19

Colour without colour – Jason Eason explains how research into light effects will transform the way cosmetics are made.

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o make up one’s face is to illuminate it, give it life, and communicate its radiance.

Through constant innovation, the science of make-up conceals what we wish to hide, veiling eyelids with transparent substances that diffract light, giving lips a thousand and one nuances, adorning nails with glitter, and powdering the skin with gold.

During the 20th century, beauty products became accessible to all. The 1920s’ fashion for a matte complexion meant applying starch or wheat flour or even fine rice flour. Then the 1930s brought lipsticks, powder-form make-up,

“A smoot h, soft and transparent skin is no less indispensable to the perfection of beauty than elegance of fi gure; and though much of the beauty of complexion depends upon nature, yet art can often perform wonders...” Anonymous author of The Art of Beauty, 1825. and nail varnish. Over the years, the powders became finer, the make-up longer lasting, and the lipsticks smoother. New materials and creative cosmetic formulations made products no longer just enhancers of beauty but also a means for skin-care.

Foundation, for instance, gives a uniform finish to the skin and a glow to the face. It also conceals pigmentary blemishes and surface unevenness, heightens the skin tone with a blend of colours, and protects skin from damage by ultraviolet rays.

Moisturizing agents and light anti-dehydration oils allow foundation to contain up to 10% absorbing or reflective pigments in the form of red, yellow, or black iron oxides or white titanium oxides. Some products contain ultra-fine pigments dispersed so evenly that a near-perfect covering effect is obtained, and mother-of-pearl microparticles produce sparkling effects in the light.

Glistening eye shadows and mascara have also become more sophisticated. Fine emulsions based on latex (which has the ability to stretch) are applied with delicate, specially designed brushes to coat the finest human eyelashes with longlasting film. Glycerin gives lipsticks moisturizing properties, and the anti-dehydrating qualities of Top: Colourful Morpho rhetenor butterfly. Lepidoptera (the insect order made up of butterflies and moths) are adorned with colours produced by nanostructures that produce intense optical effects. Image: P. Vukusic, University of Exeter Left (above and middle): Make-up that creates glistening colour on the human face. Images: Courtesy of L’Oréal Left (below): Metallic sheen that illustrates the phenomenon of iridescence, where colours change with the angle of view. Image: Courtesy of L’Oréal

20 Quest 3(4) 2007

lanolin derivatives and of other oily substances prevent chapping, which often affects the mucous membranes of the lips as they have no sebaceous glands (and therefore do not secrete lubricant). Lipsticks have to be designed to last when they are worn, and must maintain an even distribution of pigment over time; nail polish needs to be stable when exposed to light, with pigments remaining suspended in a liquid medium for a time, then hardening on the nails when the solvent evaporates.

Cosmetics have become such big business over the years that research and innovation are a permanent feature of the industry.

Colour effects Until now, make-up has incorporated the actual colour of the material that appears on the skin. In other words, the pigments in the make-up absorb light and reflect a small part of the incident light.

How do we improve on this? Physics provides answers through the ways in which the structure of the materials used can create optical effects that replace the role of pigment.

With the aim of creating a new generation of cosmetics, L’Oréal researchers observed structures in nature with a view to emulating them. They were inspired by the intense colour effects found on the Morpho butterfly wing, by the iridescence of peacock feathers, and metallic sheen – all of these seem to have colour even though the materials that make them up have little or none. The colour we perceive is, in fact, the interplay between light and the structure of such materials at the minutest micrometre or submicrometre level. These optical phenomena are based on the interference, diffraction, and diffusion of light (see box on opposite page), as described originally by Isaac Newton and Lord Rayleigh1. If make-up structures can mimic those of nature, the colour of pigments will no longer be crucial.

This challenge has still to be met, involving as it does the production of nanostructures that nature took millions of years to evolve. Recent progress in materials science and manufacturing techniques, however, allows the possibility for make-up and hair-colour to take on unparalleled hues and visual effects. The structures must be manufactured on the same scale as the wavelengths of light in the visible spectrum – in blue, in red, and other colours – for make-up formulations to be capable of mimicking them.

Physicist Peter Vukusic at the University of 1. Isaac Newton (1642–1727), English mathematician and physicist, published his theories about light and the spectrum in 1672 and summarized them in his Optikcs (1704). Baron Rayleigh (John William Strutt) (1842–1919), won the Nobel Prize for physics in 1904. Rayleigh scattering describes the reflection of photons deflected by particles in the medium through which they pass.

new generation cosmetics Far right: The scales on a Morpho rhetenor butterfly Right: Diagram showing multilayer interferences on Morpho rhetenor butterfly wings.

Images: P. Vukusic, University of Exeter

Exeter, UK, specializes in photonics (that is, the study and application of light, whose basic unit is the photon) in nature. With the help of powerful scanning and transmission electron microscopes, he has explored the intimate details of ways in which matter has been shaped by the evolution of animal and plant parts, for instance, so as to control the interactions of photons in the light falling upon them and thereby create shimmering colour effects2.

Interference-based make-up Interference-based make-up technology uses the principle of ‘interference’, which occurs when two or more light waves interact, producing a resultant wave that differs from the original waves in phase and amplitude.

Where light passes through a single thin layer of material, an incident light wave is reflected at a particular angle by the first face (the upper surface of the layer) and transmitted to the second face (the lower surface of the layer), from where it is repeatedly reflected and retransmitted (a bit like a game of ping-pong between the two faces), generating a sequence of reflected and transmitted light waves. What the observer sees is the phenomenon of iridescence (or colours that change with the angle of view)3.

To increase the reflection coefficient – in this way enhancing the iridescence – the number of layers must be increased and stacked in a particular way to achieve the desired effect.

Multilayer products can alternate up to 200 layers of polymers. The more uniform the thickness of the various layers, the purer and smoother the reflected colour effects.

Making cosmetics that mimic such iridescent effects is a complex task. It means, first, creating the structures; second, creating them on a substrate as limited in area as an eyelash, for example; and, third, ensuring the safety of applying them to people.

Photonic make-up technology – based on the principles of optics and properties of light rather than relying, as before, on chemistry and pigment – is still in its infancy and needs further refinement.

But the dream has begun to become reality – to mimic nature by creating colour without colour. ■ Jason Eason is Scientific Director at L’Oréal, South Africa.

2. In recognition of his work, Peter Vukusic received the L’Oréal Foundation prize “The Art and Science of Colour” in 2004.

3. The iridescent effect may be obtained by, for example, depositing a thin layer of metal oxide or silica (as the upper layer) on a substrate with a different refractive index such as mica or glass (the lower layer).

Right: Image of a cross-section of a Morpho rhetenor butterfly wing, taken with a transmission electron microscope.

Image: P. Vukusic, University of Exeter

Make-up and applied physics Iridescent natural structures – such as a butterfly wing – are composed of comparatively simple basic patterns arranged in a more or less complex manner but at intervals of the same order or size as the wavelength of light in the visible range. These periodic patterns may be layers of the same or differing types, ridges or bumps formed on a surface, or small rods or spheres packed within a given volume. The interactions between light and such structures give rise to diffraction* or interference* phenomena, which create colour effects under certain conditions that we can now predict.

Human beings perceive colour through the interaction between light and the matter of the observed object as well as its form. Matter responds to light at the microscopic level of the atoms of which that matter is composed. The energy carried by the photons is transferred to the electrons orbiting the atomic nuclei, raising the electrons to an excited state. Their return to a state at rest (known as the ‘ground state’) can occur with or without an accompanying emission of light.

If the photon is absorbed, only some of the light may be emitted, and this is typically the effect of colouration based on pigment, as with paint or conventional make-up. If such absorption occurs in the visible spectrum (that is, in the range of wavelengths of 400–770 nm), the reflected or transmitted light lacks one or some of its components (that is, one or more of the colours is ‘lost’) and, by inference, the remaining (or observed) colour is perceived as complementary to the colour absorbed.

When the return to the electron’s ground state is accompanied by the emission of a photon, the energy level of that photon cannot be greater (and can be less) than that of the photon which caused the original excitation. For example, if the light that causes the electrons’ excitation is blue, the light emitted can also be blue (or towards or beyond the red end of the spectrum). This tells us about the electronic structure of the material being illuminated.

A distinction may be made between two possible cases of the interaction of light and matter.

■ Where the dimensions of the (illuminated) structures are large in relation to the wavelength (of the order of half a micrometre), the phenomena will be those of refraction** plus those of dispersion***. Examples from nature include the rainbow (that is, the refraction and dispersion of light through raindrops) and prisms.

■ Where the dimensions of the surface structures are comparable to the wavelength, the phenomenon is that of diffraction of the light wave, as may be observed in opals and the beetle carapace. * Diffraction arises when waves spread or bend as they pass through an aperture or round the edge of a barrier. Interference results when the diffracted waves subsequently interfere with each other, producing regions of reinforcement and weakening. ** Refraction is the change of direction that occurs when a beam of light passes at an angle from one medium to another with a different refractive index. *** Dispersion occurs when a ray of light of mixed wavelengths is split up by refraction into its component parts.

Quest 3(4) 2007 21

Measuring up Q

Nuke science

Think you’re clever?

If anyone tells you a woman’s place is in the kitchen, try going there to measure the speed of light. You need a microwave, a ruler, and some chocolate buttons. Spread the buttons evenly on a plate. Open the microwave oven and remove the turntable. Upend a cup over the spindle – you don’t want the plate to turn; you want uneven cooking, or hot spots.

Put the plate of buttons on the cup and cook at full power for about 20 seconds. Look at the numbers printed on the back of the oven for the microwave frequency, or waves per second, expressed in megahertz. When the 20 seconds are up, measure the distance between the melted buttons (hot spots). They occur at half a wavelength of the radiation, so double that distance to get the wavelength of the microwaves. Multiply this number by the frequency and the result is the speed of the microwaves, which is the speed of light – the fastest thing in the Universe.

(The Telegraph, London)

You can define intelligence as the capacity to learn, but it is still difficult to measure it impartially and make comparisons across cultures. More so across species: some creatures can learn a huge amount in a specific area only, or in an area where humans have no capacity, whereas human intelligence is considered to cover abilities such as memory, reasoning, computation, language, and formulation of concepts.

Bees can calculate the direction and distance from their hive to a food source, taking their bearings from the Sun, and communicate this information to other bees, adjusting for the Sun’s movement over time. Bonobo chimpanzees have the language capacity of three-year-old humans. A bird called the Clark’s nutcracker can remember months later where it buried up to 30 000 seeds over a large area (up to 20 km x 20 km). An African grey parrot that has been studied at the University of Arizona understands the concepts of "same" and "different", "absence," "quantity," and "size."

(BBC; PBS; Wikipedia)

Material girl The website iwaswondering.org offers instructions for making a simple “StretchO-Meter” out of a milk carton and string for measuring the stretchability or stiffness of different materials. One scientist who needs to know this kind of thing is Mimi Koehl, a biomechanist who studies how living things work physically – Nature’s engineering. For example, she has studied how kelp copes with the physical forces of sea currents.

Slow seasons If you hate winter, you can be glad you don’t live on Neptune. Each season can be more than 40 years long on that planet because of the time it takes to orbit the Sun: almost 165 years. And even summer isn’t exactly balmy: the average temperature on Neptune is about –213 °C.

Unpacking a punch Don’t get in the way of Welshman Enzo Maccarinelli. The WBO world cruiserweight boxer is twice as powerful as the average person and the force of his punch equates to 3.5 tonnes. Scientists at Swansea University used motion capture technology to measure how fast a punchbag moved when Maccarinelli hit it. The technique records positions, angles, velocities, accelerations, and impulses, providing a digital representation of a motion. It can be used in various applications, from sports analysis to video games. (BBC; Wikipedia)

22 Quest 3(4) 2007

That was quick Humans don’t experience time as measured by the motion of quarks, which make up almost all the mass visible to us in the Universe. “Just as the period of the Earth’s orbit around the Sun defines the year, so the time it takes a quark to complete one cycle of its motion in a proton defines one tick of the clock of fundamental physics,” writes Robert L. Jaffe in Natural History (October 2006). “Their orbits inside protons are exceedingly small, no more than a millionth of a millionth of a millimetre (10–15 metre) across, and their motions, which approach the speed of light, are exceedingly regular.

Once around a proton takes a quark about 0.0000000000000000000001 (10–22) second, breathtakingly fast by any human measure.”

Fresh but a bit tough A fishing trawler recently caught one of the oldest creatures in Alaska, a giant shortraker rock-fish. The 1.1-metre, 27-kg fish was estimated to be between 90 and 115 years old and was caught at a depth of 640 m. The fish’s age was measured from its ear-bone, or otolith, which has growth rings like a tree trunk. The world’s fishing industry catches about 27 million tonnes of unwanted fish (bycatch) every year – about one fish in four is wasted. Longline fishing, in which baited hooks are trailed behind

commercial fishing boats, also kills an estimated 250 000 seabirds every year. It’s thought that around 40 000 albatross die this way annually in the Southern Ocean alone. (BBC)

Science fiction What can’t you measure and express as a statistic? You might have thought that literature was one answer. But now a professor of English literature has turned to mathematical analysis of novels to advance literary theory. The problem with reading, says Stanford University’s Franco Moretti, is that no one person can keep up with everything that’s been written. And as more and more texts are made available online, a huge mass of searchable information grows. But literary analysts have to start posing useful questions about those data.

“We still work with the interpretative model and one great book at a time. We must find a way to combine the individual who reads a single work with great collective efforts and vision." Moretti wants to be able to make objective statements about what is typical or proportionate about texts or cultural practices such as publishing. (Science News; The Guardian; History News Network) Compiled by Ceridwen

How do you like “Science for the Classroom”?

As a legacy of the Science Tunnel exhibition, at SciBono Discovery Centre, Johannesburg, which ended in July 2007, the Max Planck Society is making educational material available to South African schools in the pages of Quest.

The first 4-page pullout starts on the next page, and the second, on “Superconductivity”, will appear in the next issue.

Both will be available on the Quest website (www.questsciencemagazine.co.za).

LET US KNOW what you think of these inserts. Did you enjoy reading this first one on carbon? Is it helpful in class?

Do you want more educational material of this sort? E-mail your comments to the Editor at editor.quest@iafrica.com or fax them to (011) 673 3683. Mark your comments “Quest and Max Planck Society Educational Material”.

Q Interviews

Women in engineering There’s nothing to stop women from forging ahead in what often seems a man’s world.

Civil engineers Danai Magugumela and Althea Povey tell readers what’s involved.

What decided you to become an engineer?

▲ ▲

Danai Magugumela (DM): Having done well in mathematics and science, I had always aspired to study medicine, the career of choice in those days. But part of me wanted a job involving outdoor work, building or developing things from scratch. I was accepted to study agronomy (soil science) but, after one semester, the faculty closed down. The most similar degree I could think of was civil engineering.

Althea Povey (AP): Although I was good at maths at school and really enjoyed it, I was advised to study for a general B.Sc. (engineering was not even mentioned – as was then common in the case of women, I suppose). On completing the degree, I realized that research and laboratory work were not going to keep me happy for long - my boyfriend at the time was studying engineering and I saw that the work he was doing was what I would much prefer. Not wanting to rush in without further thought (it is, after all, a 4-year degree and, I observed, a tough one too) I enrolled for a diploma in higher

education that would allow me to teach maths and science at high school. I won the ‘Best Practical Teacher’ medal, but during that year decided to study engineering. It’s probably one of the best decisions I’ve ever made.

I never thought of engineering as a ‘men-only’ profession, perhaps because, at university level, there is not a notable distinction between men and women per se; instead, you are judged on your ability to do the work. I was also a little older than the average first year engineering student when I started the degree. This, together with the fact that I had been brought up (by my Dad!) to believe I could do anything if I wanted to enough, could explain my attitude at the time.

Amazingly, all my studies have helped my career (no learning is ever wasted). In my work in water and wastewater treatment, my B.Sc. with biochemistry and microbiology has been most useful. I still love teaching (to the benefit or irritation of the candidate engineers I work with) and enjoy lecturing now and then at local universities.

Above: A view of the steel reinforcement for the concrete structure of a Dortmund-type clarifier under construction. The clarifier is used in wastewater treatment to separate sludge from liquid effluent. Adelaide Wastewater Treatment Works, Eastern Cape. Image courtesy of Kwezi V3 Engineers, Cape Town Above right: A multilane motorway.

What engineering project gave you the greatest satisfaction?

My greatest challenge was my first-ever design project in my first job after graduation. It involved widening an existing motorway from 10 to 12 travel lanes so as to reduce peak-hour traffic jams. It was exciting to apply what I had learned at university to design, punching in ground coordinates in a roadway software programme that produces all the curves and lines of the freeway. I also had to work out from ground contours what the vertical profile of the road looked like. It was rewarding to drive that stretch of road and know that my efforts would soon be applied to widen it.

The main engineering requirement was to design new horizontal and vertical alignments and tie them into the existing ones. Where the road was elevated over another one, existing bridge slabs had to be widened.

Support structures for the elevated freeway included retaining walls as well as bridge support columns, and appropriate drainage structures were needed.

The key technological issue was to tie in the newly designed lanes with the existing ones, and services such as street lighting and telephone cables had to be relocated. Once the new lanes were designed, we had to work out ways to divert vehicle traffic during construction.

The team inspected as-built drawings and took verification measurements on site to ensure that the coordinates of the existing structures were accurately known. Accurate ground information ensured accurate positioning. Being able to plot the roadway in 3D by computer-aided methods was critical for seamless tie-ins and accurate clearances. Creating something to serve a real traffic-congestion need was extremely fulfilling.

– Danai Magugumela

Image courtesy of the South African Institution of Civil Engineering

Quest 3(4) 2007 23

What’s so rewarding about engineering?

One reason that engineering is so stimulating is the great variety of different projects you undertake throughout a career, each with its own challenges and rewards.

I think of the very first project that I was involved in – the upgrading of the mountain pass between Citrusdal and Clanwilliam, which coincided with the introduction into South Africa of one of the first PC civil design programs; then there was my year as resident engineer on the construction site of the Graduate School of Business at the V&A Waterfront; the repair and maintenance programme of all the civil services on Robben Island; the conceptual design of the Mitchells Plain Transport Interchanges (for which our company won an award), and, more recently, my involvement in water and wastewater civil engineering projects.

Water and wastewater engineering epitomizes the important role of engineers in serving society and the environment. Growing urbanization has increased the demands placed on our wastewater treatment works, many of which, for various reasons, are not treating the inflow to an acceptable standard. So we see poorly treated sewage entering our rivers, streams, aquifers, and other sources of water – and sometimes this same water source also supplies raw water to water treatment plants. The poor quality of this raw water then requires more expensive and technically complex treatment methods to turn it into water safe for drinking.

The challenge for treatment process and design engineers is to find solutions that produce the required treatment standards, which are, at the same time, cost-effective in terms of capital expenditure as well as long-term maintenance and operation. This specialist discipline is practised by a relatively small group of dedicated engineers responsible for contributing to a healthy life for all. – Althea Povey

▲

What three most important qualities or actions led you to your present success? What special efforts were needed?

DM: I have been privileged to become chief executive of a consulting engineering firm. The three most important things for me have been: giving my absolute best effort to any task put before me; demonstrating passion and commitment to matters of the

24 Quest 3(4) 2007

profession as a whole; and having a keen interest and ability in working with other people (particularly in a team).

AP: I so enjoy the work I do that I’m prepared to put a lot into it. I believe that our work as engineers does more to improve people’s lives than any other profession. I am also lucky to work with people who feel as passionate about their work as I do. As to the three qualities for success, I would say – have passion for your work and do your best at all times; surround yourself with people who feel the same way (or motivate them accordingly); and base your decisions and actions on strong ethical principles.

Q Interviews Opposite page. Left below: Biological trickling filters – reservoir-like structures filled with stones that offer a low-energy way to treat wastewater aerobically. Left: A biological reactor, where oxygen is added to sewage to treat it before it goes into the settling tank.

Later in the treatment process, the liquid is thoroughly disinfected before being released into the river. Worcester Wastewater Treatment Works, Western Cape. Image courtesy of Kwezi V3 Engineers, Cape Town Right: A motorway whose construction involved complex elevation and bridge structures.

Image courtesy of the South African Institution of Civil Engineering

What constraints and benefits did you experience as a woman in engineering?

DM: Without doubt, a noticeable challenge in my early career on construction sites as an assistant resident engineer was getting the contractor’s foreman and his staff to accept that I had a supervisory role to play. Conflict situations such as contractor’s claims were difficult when intimidation and cowboy tactics were resorted to. And extended periods on a road-building site in a remote area made it often impossible to find a ladies’ toilet!

On the upside, I often found that, compared with fellow colleagues at sitesupervision level, I was treated more politely by the men, in recognition of my womanhood. It was also fun to raise eyebrows in site meetings when a client or newcomer discovered my role after initially assuming I was there to provide refreshments.

I have enjoyed and appreciated every stage of my career. Despite plans to reach the highest academic level – a doctorate in engineering – I found with time that the workplace opened up a whole new world of practical learning. Over and above the thrill of my technical projects, I soon felt keen to mentor other professionals, to identify and nurture talent, and to lead people to achieve common strategic goals. I have also tried always to promote the recruitment of women to engineering.

AP: Constraints – I’ve noticed very few. Most are based on preconceptions, and once these have been clarified, the constraints disappear. Benefits – none that I am aware of. But I do believe that the fact that women think differently to men helps a team or organization, as it brings different perspectives to decision-making and problem-solving. ■

Danai Magugumela is the Chief Executive officer of BKS Engineering and Management, an engineering consulting firm that executes multidisciplinary infrastructure projects in South Africa and elsewhere on the continent.

Althea Povey has worked in a range of civil engineering projects. She is a director on the Board of Kwezi V3, one of South Africa’s largest consulting engineering firms, and the Divisional Director responsible for the Water and Wastewater Treatment and the Structural Engineering divisions.

Postgraduate study in strong materials MSc and PhD by research Opportunities exist for postgraduate study at MSc and PhD level with the DST/NRF Centre of Excellence in Strong Materials (CoE-SM). Bursaries of R40 000 pa for MSc, and R65 000 pa for PhD are available.

The Centre is hosted by the University of the Witwatersrand, in partnership with the Nelson Mandela Metropolitan University, the Universities of Johannesburg, KwaZulu Natal and Limpopo, Mintek and NECSA. Strong Materials are materials that retain their distinctive scientific and applied properties under extreme conditions and have established or potential commercial applications.

Applicants have a wide choice of research areas, including: Hardmetals: Manufacturing, testing and characterisation of tungsten and vanadium carbides.

Ceramics: Multi-component, ultrahard-phase continuous composites for cutting tools and wear parts.

Diamond, Thin Hard Films and Related Materials: Laser-based methods are used to measure stresses, elastic and structural properties of bulk solids and thin, hard films, and to study defects in materials. Developments and studies using diamond include radiation detectors, beam optics, radiation damage effects and surface properties.

New Ultrahard Materials: Computational and experimental investigations of potentially new ultrahard materials including advanced borides, carbides, nitrides and oxides.

Strong Metallic Alloys: Development of new alloys, e.g. superalloys for high temperature applications, property studies of metals, phase diagrams and structure property relationships.

Carbon Nanotubes and Strong Composites: Carbon nanotubes (among the strongest and stiffest structures ever made) are being studied for potential chemical and mechanical applications.

PleASe CoNTACT: Dr Tanya Capecchi Tel: +27 11 717 6873 Fax: +27 11 717 6830 email: Tanya.Capecchi@wits.ac.za Quest 3(4) 2007 25 www.strongmaterials.org.za

Sian Tiley-Nel explains some of the meanings behind clay figurines and bone hairpins, copper armlets, iron bangles, gold leg rings, necklaces, decorative glass beads and other objects excavated at Mapungubwe. They testify to Iron Age technology – and to the place of women in their society.

Images courtesy of the University of Pretoria, Mapungubwe Museum and Archive

Top right: Indigenous shell beads manufactured from ostrich eggs.

Above right: Mapungubwe and K2 ceramics are remarkably symmetrical, with well finished surfaces and refined decoration.

Above: Gold rhinoceros, once a symbol of royalty, found in a grave on Mapungubwe Hill in 1933.

Below: Ceramics displayed in the Mapungubwe Museum in the Old Arts Building, a national monument at the University of Pretoria.

The Mapungubwe Museum Founded in June 2000, the Mapungubwe Museum (on the University of Pretoria’s Lynnwood Road campus) is housed in the Old Arts Building, itself a national monument. It contains the archaeological collection from the Mapungubwe Hill and K2 Iron Age sites, which have been under the custodianship of the university since 1933.

This collection of original material of national significance is used for education, tourism, training, academic study, and conservation and research. The permanent exhibition of the 1 000-year-old artefacts reflects the cultural significance and diversity of an early African trading kingdom.

The museum is open to the public Tue–Fri, 10:00–16:00. For information phone (012) 420 3146; fax (012) 420 4918, or e-mail mapmuseum@up.ac.za. Entrance is free of charge.

26 Quest 3(4) 2007

P

ersonal adornment tells a story in every society. Objects worn to beautify the body also represent social values, marital status, and age. The convergence of artefacts, adornment, and archaeology on public display in the Mapungubwe Museum at the University of Pretoria presents many objects associated with women of the past who once were embellished with ornaments – and who took their place as custodians and preservers of sustainable traditional life.

Museum collections are a way of shaping and transforming perceptions and interpretations of the past. Traditional beadwork, indigenous ornamentation, and ancient crafts find themselves in a contemporary context. Here, they accrue and restore appreciation and status – in a form that contrasts significantly with that of deep archaeological deposits. As a scientific discipline, archaeology investigates and interprets the past, including artefacts (also called ‘cultural material’) left behind by ancient societies.

Excavated objects are invaluable sources of information about the people who made them, where they went, and why a society flourished, declined, and ceased to exist. Mapungubwe, for example, situated in the central Limpopo–Shashe basin, was arguably the first southern African capital or kingdom. This 13th-century Iron Age site in Limpopo Province reveals part of our little-known southern African prehistory.

The Mapungubwe collection showcases what we have found of this past civilization.

It exhibits rare and distinctive Late Iron Age artefacts from two renowned sites known

Above: A typical example of K2 turquoise trade beads.

Top right: Cowrie shells (Cyprea annulus) were among the most widely used currencies.

At Mapungubwe they were also used for ornamentation.

as K21 (dating back to AD 1030–1220) and Mapungubwe Hill2 (AD 1220–1290). Amongst other things, there are gold ornaments, copper and iron articles, clay figurines, ceramic vessels, trade glass beads, and refined (worked) shell, ivory, and bone objects. All are valued for their cultural significance and antiquity, but their relevance, meaning, and interpretation have new importance in a contemporary South Africa searching for its indigenous roots, and such objects also open up discussion about the role of women in Iron Age society.

Archaeological thinking When archaeologists explicate artefacts, they aim at a balanced consideration of the roles, relationships, and beliefs of people in past societies. But the interpretations include a subjective element – they are often widely debated, and they are sometimes influenced by gender prejudice.

The field of study known as ‘gender archaeology’ examines the evidence to explore the relative social and political positions – class and status – of women and men, as well as their family life and the authority and power they wielded. According to archaeologist Alex Schoeman, for instance, re-analysis of the evidence suggests that women at Mapungubwe could have played important roles in the emergence of sacred leadership, which incorporated functions such as rainmaking and political control. At the same time, women also seem to have been crucial in the agricultural activities so important for their community’s sustainability, just as they are known to have done in more recent traditional African societies, where growing crops was the responsibility of women, and in some communities remains so to this day.

Above: Gold beads were excavated in their thousands at Mapungubwe Hill.

Below: Ornamented gold sceptre found in a grave on Mapungubwe Hill, and clay figurine torso fragment from K2 with lines incised as decoration.

▲ ▲

Figurines and beads The practice of adornment derived from two powerful and culturally specific sources – rich indigenous traditions of making and wearing adornment, and the ancient mining and glass-bead trade. Many objects from K2 and Mapungubwe Hill also bring together craft, tradition, and ritual objects. The indigenous bone, shell, and pottery

beads; the manufacture of spindle whorls for spinning indigenous cotton; the ceramic vessels and metal ornaments excavated – all these are a reminder that Iron Age societies had the creative skills and craftsmanship to fashion raw materials into ornaments and jewellery long before the onset of the colonial period.

Most objects in the Mapungubwe Museum were made by and adorned women and men, and were buried with them to indicate an individual’s high social status. Furthermore, clay figurines, ceramic vessels, and clay and shell beads buried with women typically demonstrate the craftsmanship they had exhibited as skilled manufacturers of such objects.

Researcher Adri Humphreys recently investigated the gender forms crafted into clay figurines recovered from the sites of K2 and Mapungubwe Hill, and found considerable emphasis on women.

Although many of the figurines now exist only as broken fragments, gender could often be identified from body parts. Prominent navels, breasts, and steatopygeous (enlarged) buttocks appear as small lumps of clay added after the body was formed, clearly distinguishing it as female. Of the 74 figurines recovered from the sites and examined, 41 were obviously female and the only distinguishable male one came from K2 and consisted of a lower torso with male genitals.

Some of the female figurines carried either an incised line or puncture (dot) decoration on the torsos, concentrated around the navel and along the spinal column. This probably represents some form of scarification (that is, tiny punctures or superficial incisions made in the skin) – important symbolism relating to fertility and child-bearing, where the navel is mostly associated with young girls. Such clay objects are an example of artefacts that help us to understand more about Iron Age rituals and symbolic meanings, and the way in which particular gender roles were viewed in a past society.

1. The huge ash midden (mound) complex at the site, named ‘K2’ by an early archaeologist, was by far the largest Iron Age site of the period and was radiocarbon-dated (by John Vogel) as from AD 1030 to 1220. The contents show increasing sophistication of pottery, metal, and other artefacts, with many trade glass beads, including those melted down to form ‘garden roller’ beads (see next page). During this period the settlement pattern changed as cattle were moved out of the central kraal.

2. Mapungubwe Hill (AD 1220–1290) still evokes powerful symbolic associations related to rain and the presence of ancestral spirits. Accumulated wealth led to separation of the commoners from the ruling class, who lived on top of the hill. The elite hilltop settlement yielded royal graves, gold, copper, and other ceremonial artefacts and trade goods such as glass beads and Chinese ceramics.

Quest 3(4) 2007 27

Left: Large indigenous garden roller beads from K2, which were manufactured locally by reworking trade glass beads. ▲

Of the artefacts that attest to international trade, glass beads are perhaps the most abundant. The earliest evidence of trade relations between Africa and the rest of the world has been documented from glass-bead evidence, as the written record is sparse.

Beads were objects of adornment but they were also prestige goods, exchanged and traded via the Indian Ocean network over much of Africa. In as early as the 8th

Above: Mapungubwe Hill trade glass beads originating from India, Egypt, Asia, and Arabia.

century AD, they were exchanged for ivory and gold between southern Africans and traders along the East African Coast who came from Egypt, India, south-east Asia, Persia, and Arabia.

Glass beads were not manufactured at Mapungubwe, but there is clear evidence at K2 of glass re-working, where smaller blue-green traded glass beads were crushed, melted, and shaped in clay moulds, creating the unique large beads of the Limpopo Valley commonly known as ‘garden roller’ beads. These were valued as objects of beauty and wealth, and became integral to this Iron Age society, denoting the status of women. A single female royal burial on Mapungubwe Hill contained over 28 000 black trade glass beads originating from Egypt, which signified the great social importance of the deceased.

The colours of the trade beads had symbolic meanings. White beads denoted purity, black was often associated with the ancestors, pink alluded to poverty, and green signified fertility.

Glass beads, stone beads, and organic beads of bone, shell, and ivory were encoded into traditional dress, bangles, necklaces, waistbands, and hair.

There is little doubt, from the historical and archaeological evidence, that the status of women and men was a complicated issue. The African Iron Age is generally characterized by male dominance, and Mapungubwe has long been interpreted as a male hierarchy of ruling power and authority. Women fulfilled their main roles as wives and mothers but, in turn, also held

Fact file Q Some Mapungubwe facts The ancient kingdom

Conservation milestones

■ Mapungubwe was the centre of the first known powerful indigenous kingdom in southern Africa, starting more than 1 000 years ago ■ There are over 400 Mapungubwe-related archaeological sites in the Limpopo Valley. The main centres during the Mapungubwe period were Schroda, K2, and Mapungubwe Hill.

■ The kingdom grew as a result of wealth from trade with the Indian Ocean network, combined with a ‘Nile’ type of flooding system that supported enough agriculture to feed a population of over 9 000 people.

■ High-quality trade goods found at Mapungubwe come from as far afield as China, Persia, and India. They include gold, glass beads, cotton cloth, Chinese ceramics, ivory, copper, and hides, and are evidence of a wealthy community.

■ By the 13th century, a new social hierarchy had developed and left its mark on the landscape. Mapungubwe Hill was occupied and modified to separate the leader and his elite from the commoners below.

■ The onset of the Little Ice Age (AD 1290–1300) caused drought and crop failures. The kingdom dispersed after 1300, new social and political alliances were formed, and the centre of regional power shifted to Great Zimbabwe. Mapungubwe was therefore the forerunner of the Great Zimbabwe culture.

1922 1932

28 Quest 3(4) 2007

Dongola Botanical Reserve established in the area Gold artefacts discovered and reported to the University of Pretoria, which conducts initial research and exhibits Mapubgubwe’s artefacts 1947 Dongola Wildlife Sanctuary established by Prime Minister Jan Smuts 1967 Vhembe Nature Reserve proclaimed 1970 Occupied by the South African Defence Force as a Restricted Area 1983–1984 Declaration of K2 (1983) and Mapungubwe Hill and southern terraces (1984) as national monuments 1995–1998 Northern Province and the then National Parks Board agree to form a national park in the area (1995) and first property proclaimed as part of Vhembe-Dongola National Park (1998) 1999 Gold rhino and other artefacts restoration project by the University of Pretoria 2000 Mapungubwe Museum (at the University of Pretoria) opens to the public 2001 Mapungubwe Hill approved in principle as one of the first National Heritage Sites in South Africa under the new National Heritage Resources Act 2003 Mapungubwe listed as a World Heritage Site 2004 Mapungubwe National Park World Heritage Site officially opened.

Right: Trade beads known as ‘Indian Red’.

control and authority in the agricultural and community spheres, and contributed equally to the economic and social success of their society.

Women at Mapungubwe seem, in short, to have been shapers and shifters and custodians in their society, some with a part to play in rituals and ceremonies as healers, rainmakers, and royals, and holding positions of authority and status. It is perhaps appropriate that today, in South Africa’s heritage industries, there are many women in leadership and management positions, nurturing and revealing to others the country’s historical and prehistorical traditions. ■

For more about archaeology, read Bruce G. Trigger, A history of archaeological thought (Cambridge, Cambridge University Press, 2000), and for details of archaeological finds at Mapungubwe, consult Leo Fouché (ed.), Mapungubwe. Vol. 1. Ancient Bantu civilisation on the Limpopo (Cambridge, Cambridge University Press, 1937) and G.A. Gardner, Mapungubwe Vol. 2 (Pretoria, J.L. van Schaik, 1963); Tim Hauf, Essence of a land: South Africa and its World Heritage sites (Tim Hauf Photography in association with Green Vision Foundation, 2006); A.J. Humphreys, “Re-figuring the female form: Ceramic figurines from the K2 and Mapungubwe Complex” (unpublished Honours thesis, University of Pretoria, 2005); Andrie Meyer, Archaeological sites of Greefswald: Stratigraphy and Chronology of the sites and history of investigations (Pretoria: University of Pretoria, 1998); S. Tiley, Mapungubwe. South Africa’s Crown Jewels (Cape Town, Jonathan Ball, 2005); and J.C. Vogel, “Radiocarbon dating of the Iron Age sequence in the Limpopo Valley”, in M. Leslie and T. Maggs (eds.), Africa Naissance: the Limpopo Valley 1 000 Years Ago (The South African Archaeological Society, Goodwin Series 8, 2000), pp.51–55. Useful websites include www.up.ac.za; www.mapungubwe.com; www.sahistory.org.za; and www.sanparks.org.za.

Sian Tiley-Nel is the curator of the Mapungubwe Museum at the University of Pretoria. Her interests lie in archaeological objects. As an Iron Age archaeologist and museum professional, she has over the last decade excavated, researched, and conserved the Mapungubwe collection.

Q The S&T Tourist

As a tourist destination, Mapungubwe combines natural and human heritage, rich biodiversity, great scenic beauty, and archaeological remains.

T

he Mapungubwe world heritage site lies on the northernmost border of South Africa, in the Limpopo Valley, some 70 km west of Musina, where the borders of Zimbabwe, South Africa, and Botswana meet at the confluence of the Limpopo and Shashe Rivers.

The vertical cliffs of the flat-topped sandstone Mapungubwe Hill tower 30 metres above the surrounding landscape, forming a natural fortress with spectacular views into all three countries.

Visitors to Mapungubwe (meaning “place of many jackals”) can experience many of the pleasures of cultural and historical tourism, including San rock art, archaeology that explores Stone Age and Early and Late Iron Age times, ancestral graves, and the Mapungubwe military post, as well as oral traditions and tales associated with specific locations.

Gold-working took place on this site, which seems to have heralded the period of goldmining and trade with the east African coast, and goldplating techniques used here involved covering carved wooden objects with gold sheeting and securing it with tacks of gold. Among the best-known objects excavated by archaeologists at Mapungubwe are a gold rhinoceros and a gold bowl dating from about AD 1200.

Apart from visits to the home of a remarkable civilization, game-viewing is also on offer. Elephant, giraffe, white rhino, eland, gemsbok, and numerous other antelope species occur

Above: Mapungubwe and view of the Limpopo and Shashe Rivers.

Left: Baobab (Adansonia digitata) in the Mapungubwe National Park.

naturally here, and, at night, lions, leopards, hyenas, and jackals can be heard in their ancestral hunting grounds.

The area is known for its great diversity of reptiles and invertebrates and about 400 bird species – as well as its mopane woodlands and some of the world’s biggest baobab trees.

It is said that Mapungubwe is like a phoenix, rising out of the mists of the mysterious past, and a symbol of eternity. – At Meyer, National Youth Development Trust For more information, contact South African National Parks by phone at (015) 534 2014 or fax (015) 534 0102 or e-mail normanm@sanparks.org, and visit http://www.sanparks.org/parks/mapungubwe.

There are several options for overnight stays. Leokwe Camp is Mapungubwe’s main camp, in the eastern section of the park among the sandstone cliffs, with a lookout point for game-watching. Limpopo Forest Tented Camp, in the Limpopo riverine forest, is close to the Maloutswa Pan hide, which offers birding opportunities. Tshugulu Lodge is a luxury guest lodge and offers an exclusive eco-trail. Vhembe Wilderness Camp, in the eastern section of the park, is on a small ridge within a valley, not far from the Limpopo River and Mapungubwe Hill. There is also the Mazhou camping site.

Quest 3(4) 2007 29

Careers in S&T Q

C

Images courtesy of the University of Pretoria, Mapungubwe Museum and Archive

Top: Sifting an archaeological deposit at the base of Mapungubwe Hill.

Above: Education in archaeology is important for introducing young people to the riches of South Africa’s heritage.

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areers associated with ‘heritage’ are wideranging, so anyone wanting to work in this area needs to know exactly which part of it interests them most. Here are a few definitions.

Heritage is something inherited, transmitted from the past, or handed down by tradition.

Cultural heritage can take the form of monuments and museum collections, as well as traditions, customs, and practices passed down through generations, all of which are valued as a legacy that needs to be conserved and preserved for the future. Archaeology is the study of the human past based on scientific analysis of the material remains of ancient cultures; related branches include archaeozoology (the analysis of animal remains found at archaeological sites) and archaeoastronomy (encompassing the study of astronomical principles employed in ancient architecture and the practice of astronomy in past cultures).

Going further back, prehistory relates to human development before the appearance of the written word. The prefix palaeo(from Greek palaios meaning ‘old’) is associated with the study of prehistory, such as palaeobotany (the study of fossil plants) and palaeoethnobotany (the study of fossil seeds and grains to further archaeological knowledge, especially of the domestication of cereals); palaeontology (the study of fossils to determine the structure and evolution of extinct animals and plants and the rock strata in which

they are found); and palaeoanthropology (relating to the earliest varieties of humankind).

Academic work and research relating to ‘heritage’ is increasingly multidisciplinary and collaborative, requiring tertiary-level training as well as good communication skills, patience, dedication, and attention to detail. The scope is broad, including disciplines from across the physical and natural sciences – the botanist, biochemist, zoologist, entomologist, palaeontologist, climatologist, ecologist, mineralogist, and physical anthropologist all play a role.

‘Heritage science’ has three main aspects, each requiring specialized training. First, collection and observation, where experts record and collect moveable items in the field, including pottery and ancient tools. Immovable items, such as rock paintings, are recorded in photographs and sketches. Next follows processing: here, the material is recorded, dated, analysed, and interpreted. Finally there is safekeeping, with careers including those of museum curator, librarian, and archivist.

Tourism directly involves the broader public, and interesting, well-informed guides are the public educators who bring the past to life. Those who design and care for heritage sites, however, have the task of preserving and protecting them, even as increasing numbers of visitors are welcomed there.

– At Meyer, National Youth Development Trust For further information about the range of careers involving heritage, start by consulting the relevant departments at your local university.

Q Books Gardens big and small

Ecoguide: Fynbos. By Colin Paterson-Jones and John Manning. (Briza, 2007).

ISBN 978 1 875093 66 3 Kirstenbosch – beyond words.

Photographs by Harris Steinman. (Briza, 2007).

ISBN 978 1 875093 85 4 Two fine books from Briza Publications celebrate aspects of the Cape Floristic Region, the smallest of only six floral kingdoms in the world and the most richly endowed for its size. More than 8 600 different plants species grow here, of which twothirds are found nowhere else on Earth.

The Cape Fold Mountains at the southern tip of Africa support the fynbos biome, one of the world’s most varied types of plant cover and found in over about half of the Cape Floristic Region. Fynbos evolved in response to the area’s dry summers, unique landscape, and the sandy soils from the weathering of the sandstone and quartzite rocks exposed on the local mountains. The plants are adapted to thrive on exceptionally poor soils, to withstand summer drought, and to respond by re-seeding or resprouting to periodic natural fires.

Published in full colour with photographs by both authors, the new fynbos fieldguide by photographer and writer Colin Paterson-Jones and research botanist John Manning covers more than 400 of the species of restios, heaths, proteas, annuals, herbs, shrubs, and bulbs that are found here. Each species is illustrated and described, with common and scientific names, habitat, distribution maps, flowering times, and local uses. Introductory chapters give background information about the Cape Floristic Region and the birds, insects, spiders, reptiles, and mammals for which it is also home.

The concluding “Travel Adviser” section gives visitors practical information about national parks, nature reserves, and other prime flowerviewing destinations in the area.

The Cape Floristic Region was proclaimed South Africa’s sixth World Heritage site in 2004 and comprises eight protected areas in the Western Cape, one of which includes Kirstenbosch National Botanical Garden on the eastern slopes of Table Mountain. Kirstenbosch – beyond words, by Harris Steinman, is endorsed by the South African National Biodiversity Institute and introduced by its former chief executive, Brian Huntley. It is a series of photographic ‘essays’, whose evocative closeup floral images reveal details that normally go unnoticed. Apart from the foreword, preface, and introduction, the text consists simply of short

captions that name the plants depicted.

Steinman’s preface explains his view that “every visual impression triggers an emotional response, possibly only unconscious and minor, but present nevertheless”, and that such responses are affected not just by a whole scene but also by the elements that make it up. The book exemplifies his own subjective reactions to the visual impressions offered him by Kirstenbosch – “to the interplay between light and shade, to plant shape and structure, to colour, pattern and texture, and to the elegance, delicacy and tranquility of the subjects.”

The result is a rich and unusual set of horticultural portraits that will encourage visitors to linger in the garden, to appreciate the finer details of its plants, and then, once back at home, to recall the artistry of nature in these beautiful pages.

Visit www.images-beyond-words.com for photographic links.

confusing. To make it easier, Part One of the book establishes the basics of plant form and structure, helping the reader to know what to look for when encountering an unknown tree. The authors outline diagnostic characteristics such as leaf arrangement, shape, and hairiness, as well as tree shape, size, and foliage colour, bark, flowers, fruits, seeds, and geographical distribution and habitat. Then, using a group-recognition approach (rather than one based initially on formal botanical family classifications), Part Two offers a key to 43 tree groups based on easily observable stem and leaf features – a useful first step towards identification. The illustrations and presentation are superb throughout. This is a must-have for people who love trees and want to know them better.

Making Sense of Garden Design. By Lindsay Gray, Helen Lachenicht, and Sharon Walker. (Briza, 2007). ISBN 978 1 875093 83 0. Available in Afrikaans as Sinvolle tuinontwerp.

ISBN 978 1 875093 97 7 This is a reference guide to the practicalities of turning gardening into the creation of an entire garden, with its own integrity and character, that complements the home or building that it surrounds as well as the lifestyle and habits of the people who use it. Stepby-step advice directs novices through the activities of preparing and implementing a long-term master-plan for the garden of their dreams. They find out how to consider their choices regarding design style, what plants to use where, water consumption, labour-saving devices, and personal security, in a specifically South African setting. The chapters consider aspects of design such as shape, hard landscaping, water features, plants, and colour, and end with useful plant lists for different parts of the country. This volume is an excellent tool for anyone wanting to create a garden and wondering where and how to start.

How to identify trees in southern Africa.

By Braam van Wyk and Piet van Wyk. (Struik, 2007). ISBN 978 1 77007 240 4 Complementing the authors’ earlier and more comprehensive 1997 volume, Field Guide to Trees of Southern Africa, this book aims to demystify the subject of tree identification in a region that boasts some 2 100 native tree species, plus several hundred more, imported from other parts of the world.

Such diversity makes the process of naming trees difficult and often

Richtersveld: The land and its people.

By Francois Odendaal and Helen Suich.

Photographs by Claudio Velásquez Rojas.

(Struik, 2007). ISBN 978 1 77007 341 8 This exquisitely presented volume reveals to the public an area of Namaqualand, tucked away on the Atlantic coast in the far northwest corner of South Africa, that is as remote and unexplored as it is rich in mineral and biological wealth. Sandy, rugged, and at first sight forbidding, it forms part of the Succulent Karoo, and was identified as the first entirely arid biodiversity hotspot on Earth. The book is a visually remarkable tribute to the scenery of the Richtersveld, its plant and animal diversity, and the history of its people – united through dispossession, they struggled for justice and recognition until their land claim succeeded in late 2006. It is also a book that alerts South Africans to the fragility of a part of the country where mining activities have slowed through the limited lifetime of its non-renewable resources (the wealth mined here was exported from the area rather than reinvested locally), and where the land has been degraded by stock farming in a vulnerable desert region. The future of the Richtersveld now lies less in mineral wealth and more on the people and their massive biological riches – including shore-based mariculture and nature-based tourism. This book is a striking introduction to an extraordinary place.

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Susan Chemaly explains the importance of vitamin B12 and the conditions in which scientific pioneers worked to understand it and make it available as a cure for patients suffering from pernicious anaemia.

Some definitions Vitamin: Any material essential for the growth or continued health of an organism that does not happen to be synthesized by the body and that, therefore, must form part of the diet. One animal’s vitamin is not necessarily another’s: for us, but not for mice, vitamin C is a vitamin. (From Peter and Jean Medawar, Aristotle to Zoos: A Philosophical Dictionary of Biology, Oxford University Press, 1985.)

Deficiency diseases: These diseases occur when the diet lacks some substance that is essential in tiny amounts for the body’s chemical machinery. Examples include scurvy (curable when citrus fruits – such as oranges, lemons, and limes – which contain vitamin C, are added to the diet), and beri-beri (caused by the lack of vitamin B1, which can be overcome by adding whole grains to the diet).

Synthetic vitamins have made it possible to fortify food and to prepare vitamin mixtures at reasonable prices for sale over the counter. But the need for vitamins varies with individual cases. The intake of the fat-soluble vitamins A and D, for instance, should be carefully controlled, as overdoses can be harmful.

All living cells seem to require the B vitamins. Their coenzymes are an essential part of the cell machinery of every cell alive – plant, animal, or bacterial – whether the cell gets the B vitamins from the diet or makes them itself. For Isaac Azimov, this universal need “is an impressive piece of evidence for the essential unity of all life and its descent (possibly) from a single original scrap of life formed in the primeval ocean.”

(From Isaac Asimov, Azimov’s New Guide to Science, Penguin Books, 1987.)

Vitamin B12: This vitamin is essential for good health, especially for developing red blood cells and maintaining the nervous system. Humans need very small amounts of vitamin B12 – one or two millionths of a gram suffice to prevent deficiency in a healthy adult. It cannot be made by the human body, so it must come from the diet.

Vitamin B12 is found in all animal products, but especially rich sources are liver, red meat, and milk. The B12 that comes from food is absorbed in the small intestine. Patients suffering from pernicious anaemia, however, have faulty mechanisms for absorbing B12 so they absorb very little, even if it’s present in the food they eat.

Pernicious anaemia can now be completely controlled by injections of vitamin B12 into a muscle, bypassing the need for absorption through the small intestine.

Right: Various synthetic vitamin preparations. Photograph: Cyclops

R

ed blood cells in the body are important because they contain haemoglobin, the protein enabling them to carry oxygen from the lungs and deliver it to all parts of the body. A patient suffers from anaemia when he or she has too few red blood cells, or when these cells contain too little haemoglobin.

Symptoms of anaemia are caused by inadequate supplies of oxygen to the body. They can include fatigue, weakness, the inability to exercise, and light-headedness. When the anaemia comes from sudden and excessive bleeding – after an accident, for instance – bleeding must be stopped, and the patient might need a blood transfusion.

But anaemia can also come about when the body’s red blood cell production is decreased because of deficiencies of one kind or another. One such deficiency is that of vitamin B121.

The dramatic scientific breakthroughs that revealed the body’s need for vitamin B12 and that made it possible to administer this vitamin by injection, have helped, over the past eight decades, to save the lives of people suffering from the once incurable, fatal disease called ‘pernicious anaemia’.

It’s a story that illustrates the commitment and dedication of scientists who devote their lives to pioneering work, which (in this and other fields) 1. Other deficiencies in the body that can decrease the body’s ability to produce red blood cells include deficiencies of iron, folic acid, and vitamin C. Anaemia can also be caused by increased destruction of red blood cells through, for example, enlarged spleen, autoimmune reactions against red blood cells, sickle cell disease, haemoglobin diseases, and thalassemia.

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Opposite page (top from left to right): Ball and stick models showing molecular structures: Vitamin B12 from two different viewpoints, showing the cyanide group (far left) and corrin ring (middle left), colourcoded to indicate the different types of atoms – cobalt (dark blue); carbon (grey); hydrogen (white); oxygen (red); nitrogen (light blue); phosphorous (orange).

subsequently becomes so well-known that everyone takes it for granted. It also reflects the contributions that women were making, as the 20th century progressed and they came into their own in the world of science.

Drawn using Mercury 1.4.1 and data from L. Randaccio et al., in Inorg. Chem. (2000), 39, 3403.

Ball and stick model of adenosylcobalamin (middle right), colour-coded as above.

Drawn using Mercury 1.4.1 and data from J.P. Bouquiere et al., in Acta Cryst. (1993), B49, 79.

Ball and stick model of methylcobalamin (far right), colour coded as above (see also the unit cell model on next page).

found in humans. On close examination, chemists realized that it was also an extremely complicated compound, with the empirical formula C63H88O14N14PCo. Enter Dorothy Hodgkin Dorothy Crowfoot Hodgkin (1910–1994) is considered one of the founders of the science of protein crystallography. She determined the X-ray crystal structures of cholesterol, penicillin, and vitamin B12 , as well as one of the first protein structures, insulin.

In 1964 she won the Nobel Prize for Chemistry3 for her determinations by Xray diffraction of important biochemical structures including that of vitamin B12.

When Hodgkin started her study of vitamin B12 by X-ray crystallography (see Fact File on p. 37), little was known of the chemical nature of the compound. Folkers described what he knew as follows: “that the factor was relatively stable, that it could be distributed between certain solvents, that it was of relatively low molecular weight, and that it was not a protein.”

Shortly after its isolation, Lord Todd in Cambridge (1957 Nobel Prize winner in chemistry) described it as “a substance of frightening complexity”.

In May 1948, Smith showed Hodgkin some crystals of vitamin B12 that he had grown. They were very small, deep-red in colour, and needleshaped. She found that they diffracted well, however, immediately took two X-ray photographs, and revealed that the compound had a molecular weight of about 1 500. Thereafter, ▲ ▲

First steps In the early 1920s, working on the replenishment of haemoglobin in dogs, the American pathologist George Whipple discovered that giving the animals liver to eat enabled them to make haemoglobin most quickly. In 1926, the two Boston physicians, George Minot and William Murphy, tried treating patients suffering from pernicious anaemia by feeding them liver. Their discovery that a diet containing large quantities of raw liver (400 g per day) cured the previously untreatable disease won them the Nobel Prize for Physiology or Medicine in 1934.

They ascribed the success of this treatment to the ‘anti-pernicious anaemia factor’ in liver. Eating so much of the meat was unpleasant, but it was better than being dead, and, until the late 1940s, many researchers tried to isolate the curative factor in liver.

In 1928, Edwin Joseph Cohn and his team at the Harvard Medical School (USA) prepared a concentrate from liver a hundred times as potent as liver itself.

In the 1940s, chemists at the Merck Laboratories in America found that this concentrate could accelerate the growth of certain bacteria, which reacted to it in a similar way to that in which they reacted to thiamine or riboflavin (both of which were already known as belonging to the vitamin B family2). This discovery told the researchers that the curative factor was a B vitamin; they called it vitamin B12.

By 1948, using bacterial response and chromatography (a technique for separating a mixture), Karl Folkers at Merck had succeeded in isolating pure samples of vitamin B12, closely followed

by Ernest Lester Smith in England. Its red colour seemed to resemble the colour of known cobalt compounds and further analysis showed that it did indeed contain cobalt. Now named cyanocobalamin, it is the only cobaltcontaining compound that has been

2. In 1934, Robert Runnels Williams, director of chemistry at the Bell Telephone Laboratories (USA), managed, after 20 years of effort, to separate enough vitamin B1 from tons of rice hulls until he had enough to work out its complete structural formula. Unexpectedly, it contained an atom of sulphur (theion in Greek), so the vitamin was named thiamine.

Also in the early 1930s, the Austrian chemist Richard Kuhn and his associates isolated vitamin B2. It was

yellow in colour, and the carbon chain attached to the middle ring is like a molecule called ribitol, so the vitamin was called riboflavin (after the Latin word, flavus, meaning ‘yellow’).

3. Only three women have been awarded the Nobel Prize for Chemistry. The other two were Marie Curie in 1911 and Irène Joliot-Curie (with her husband Frédéric) in 1915.

Drawn using Mercury 1.4.1 and data from L. Randaccio et al., in Inorg. Chem. (2000), 39, 3403.

Left: Dorothy Hodgkin (1910–1994).

Below: Vitamin B12 solution.

Heroic isolation of the ‘anti-pernicious-anaemia factor’ In 1947, the team of Karl Folkers, Thomas Wood, Norman Brink, Edward Rickes, and Frank Koniuszy (Merck Laboratories, USA) isolated red crystals of vitamin B12, from a fermentation broth of Streptomyces griseus (bacteria that also produce the antibiotic streptomycin), and also from large quantities of liver. Randolph West then showed that vitamin B12 produced remission in a patient suffering from pernicious anaemia, confirming that vitamin B12 was the long-sought ‘anti-pernicious anaemia factor’.

Shortly thereafter, E. Lester Smith and L. F. J. Parker (Glaxo Laboratories, UK) isolated crystalline vitamin B12 as well as vitamin B12a (a naturally occurring form of the vitamin).

Isolating the ‘anti-pernicious anaemia factor’ from liver has been called ‘heroic’ because it is present in such tiny quantities that several tons of liver were needed for the work. Another problem was the shortage of patients with pernicious anaemia and the reluctance of medical doctors (who have to consider their patients) to use experimental medication.

The vitamin B12 supplied nowadays in pharmaceutical preparations, such as vitamin B12 injections, multivitamins, and tonics is prepared using bacterial fermentation because only bacteria can manufacture it.

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the determination of the structure of vitamin B12 by chemical means and by the technique of X-ray diffraction proceeded in parallel.

The task was almost hopelessly daunting. The molecule was very large (about five times as large as vitamin B1, for instance), so the calculations would have to be worked out in three dimensions at a time when most crystal structures were calculated in two dimensions only. This complicated the task greatly. The presence of the heavy metal, cobalt, however, brought hope that the structure could be solved, for it would show up clearly in analysis (as relatively bright spots in a diffraction pattern), giving researchers a starting point from which to work.

Nothing daunted Research conditions today make those of half a century ago appear almost unimaginably primitive. Those wanting to extend the boundaries of knowledge couldn’t allow themselves to be deterred by the fact, for example, that computers were relatively unsophisticated and difficult to access. Woman scientists could not be put off by circumstances that disadvantaged them. The only response was to develop high levels of stamina, resourcefulness, accuracy, and imagination – and to work very hard.

John H. Robertson, who worked with Hodgkin in the 1950s, described her inspired ability to guess the structure of part of a complicated molecule from an X-ray photograph or electron density map: This ability to jump to the correct conclusion when the evidence was incomplete, or before the evidence had been properly sifted, was

Below: Vitamin B12 crystals, enlarged 125 times.

Image from Vitamin B12, edited by B. Zagalak et al., Berlin, 1979.

Above: Ball and stick model of methylcobalamin (see also the model on the previous page), showing the unit cell that is the basic building block of the crystal, repeated in three dimensions.

The unit cell contains four molecules of methylcobalamin, with the atoms colour-coded as follows: cobalt (dark blue); carbon (grey); hydrogen (white); oxygen (red); nitrogen (light blue); phosphorous (orange). Drawn using Mercury 1.4.1 and data from L. Randaccio et al., in Inorg. Chem. (2000), 39, 3403.

uncanny. Sometimes it seemed almost illegitimate. ‘Women’s intuition’ it was often said; but really it was the product of her phenomenal knowledge of relevant chemistry and physics, her long experience, her marvellous memory for detail and her tirelessly active mind. Here is a factual example: … when the entire structure [of vitamin B12] has been fully determined, [the] CN (cyanide) group and its position seem obvious enough. But in those early days, nothing was completely obvious...; the confidence with which Dorothy drew her conclusions about the cyanide group... was at that time positively an embarrassment. Nevertheless, she proved in due course to be absolutely right, as usual.

From her twenties, Hodgkin suffered from severe rheumatoid arthritis and her hands and feet gradually became distorted. Despite her crippled hands, however, she was a skilled experimentalist. Robertson described her ability as follows: Some of the B12 materials ... were available to us only in the form of a few tiny solid clumps; single crystals were present but all hopelessly welded to one another. These clumps were themselves smaller than a millimetre, yet this was all there was.

But they were not hopeless. Dorothy chopped out a usable single crystal from them. Her wizardry with those fingers of hers was astonishing – to mention another example: persuading solutions of (vitamin) B12 to be

saturated and to crystallize inside a thin-walled capillary (tube), depositing a nicely shaped single crystal where it was wanted inside the tube and beautifully free from adhering crystallites.

This tribute illustrates not only Hodgkin’s skills as an experimental manipulator but also the first essential of X-ray crystallography – a good single crystal of suitable size. A crystallographer with the ability to grow good crystals is like a gardener with ‘green fingers’. The early vitamin B12 crystals were dried in air and were a little cracked. Hodgkin started growing larger and better crystals of the vitamin from water; these ‘wet’ crystals contained more water molecules than the previous ones, and gave more reflections.

Since the molecule required work in three dimensions (in the days before sophisticated and accessible computers), the calculations were long, laborious, and complex. But, recalled an admiring Robertson, Hodgkin “had a happy knack of pressing ahead, slowly, unruffled, with buoyant cheerfulness, often with sheer merriment, through these threedimensional thickets of uncertainty.”

In the early and middle 1950s, Hodgkin and her group determined the crystal structures of ‘air dried’ and ‘wet’ vitamin B12 as well as the crystal structures of some molecules related to vitamin B12. Jennifer Pickworth Glusker, the graduate student who worked on the hexacarboxylic acid, later said that Hodgkin and the rest of the group kept her in the dark about the possible

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having her husband’s full support in her career. Her ability to switch focus enabled her successfully to combine her professional work with her role as a mother of three children. Her friend and fellow chemist, Max Perutz (who shared the 1963 Nobel Prize for Chemistry with John Kendrew), described it thus: Some women intellectuals regard their children as distracting impediments to their careers, but Dorothy radiated motherly warmth even while engaged in writing crystallographic papers.

Concentration comes to her so easily that she can give all her attention to a child’s chatter at one moment and switch to lattice transformations the next without any sign of strain.

When she studied chemistry at Somerville (her women’s college at Oxford) in the late 1920s and 1930s, however, the environment was not friendly to women intellectuals. Her first research student, Dennis Riley, described the university as “a masculine stronghold and the science faculties even more so”. He found that “several eyebrows were lifted” when he chose to do his final-year research project “in a new borderline subject with a young female who held no university appointment but only a fellowship in a women’s college.”

Oxford had admitted women as students since 1920, but their number was limited by statute to 20% of the number of male students. Women were not admitted to most clubs or societies; women medical students were relegated to a separate room in the Department of Human Anatomy when doing dissections.

Her laboratory in Oxford, once she began her research career in earnest there after 1934, was a room in the Oxford University Museum next to the Chemistry department, and was approached through a maze of zoological exhibits, including the skeletons of several large mammals.

Because the gothic windows were just below the ceiling of the room, it was necessary to climb a ladder (carrying a precious sample) to use the optical microscope on a bench on a platform in the light of the window. Hodgkin and her co-workers and students did their writing and calculations at tables in the laboratory, blithely ignoring the danger from the high-voltage electricity cables and the X-radiation produced by the X-ray generators. Riley writes: … safety precautions were slim and

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structure of the selenocyanide derivative of vitamin B12 so that she could work in an unbiased way. This is how she described her calculations, in the days before computers were available.

The calculation … involved six weeks of hard work day and night for a graduate student (me) using a Hollerith adding machine with punched cards…. Since the machine could not subtract, the punched cards (which effectively contained entries from Beevers-Lipson strips, i.e. cosine or sine values at intervals of 1/60 of the cell) had to be turned upside down to obtain negative values. To keep a check on this the tops of the cards were painted with differently coloured inks to indicate how they should be turned at various stages of the calculation. All three-dimensional maps were prepared by copying the numbers on to a grid and then contouring them by hand.

Kenneth Trueblood came to the rescue, volunteering to do the calculations using an early computer (the National Bureau of Standards Computer at the University of California, Los Angeles). This exercise, as one of the first computer calculations of an Xray crystal structure, was filled with trials and tribulations. One of them occurred when Trueblood made a proofreading error, which resulted in an atom being in the wrong place by 12Å units (more or less equivalent to the width of a molecule of vitamin B12). He wrote to Hodgkin in despair: … nothing could be more crushing, we have just discovered … that a mistake was made in x of atom 41, by a factor of 10 – 0.717 was used instead of 0.072. Consequently all that labor was totally wasted. I proofread the list myself and God only knows how I overlooked it – naturally at the moment I’m too discouraged to care how. Sometime soon we’ll start again.... Twenty minutes ago the Fourier and Structure Factor lists were on a desk upstairs about to be put in the mail to reach you at once. I doubt now that you will want them. We’ll send them however if you do.

Hodgkin replied in a telegram: CHEER UP. SEND EVERYTHING AIRMAIL. DOROTHY From these studies, the structure of vitamin B12 (see figure) was worked out.

As a woman scientist of her generation, Hodgkin was fortunate in

Above: The structure of vitamin B12. In the centre of the molecule is the cobalt atom (blue).

Working outwards, the cobalt is attached to four nitrogen atoms belonging to a nearly flat but complex organic ring, known as the corrin ring (magenta). Above the plane of the ring at the top of the molecule, a cyanide group (red) is attached to the cobalt. This is the ‘top’ of the molecule. On the periphery of the corrin ring are several amide side-chains. Below the plane of the ring at the ‘bottom’ of the molecule, one of these side-chains is attached to an alcohol, which is attached to a phosphate group, which, in turn, is attached to a sugar and an organic base – this can be thought of as a ‘tail’ (green).

The tail can either be attached to the cobalt atom (as shown) or it can hang loose. When the ‘tail’ is attached, the attachment occurs through a nitrogen atom from the organic base.

The structure of the corrin ring (named after ‘core’) was a completely new discovery by Hodgkin and her team, and could not have been predicted from the chemical techniques of the time. The ring was not completely flat as in the porphyrin ring, found in chlorophyll in plants and in haemoglobin (the oxygen-carrying protein in the blood of humans), but slightly buckled on one side. The structures of the side-chains on the periphery of the corrin ring, including the one containing the nucleotide or ‘tail’, were completely worked out. Even the number of molecules of water associated with each molecule of vitamin B12 was determined, as 18 in the ‘air-dried’ crystals and 25 in the ‘wet’ crystals. After this pioneering work, the research on vitamin B12 and its derivatives goes on....

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mainly consisted of a notice saying ‘Danger – 60 000 Volts.’ It would have been simple to electrocute oneself. Indeed, during the war, an overzealous Home Guard nearly did.

I, as usual, was in the lab around midnight when a local yokel dressed in khaki burst in and menaced me with a rifle and a fixed bayonet which, in his excitement at having actually captured a dangerous spy or saboteur, wavered perilously near a cable at 40 000 Volts.

The laboratory was poorly equipped and money was tight. Barbara Low, one of Hodgkin’s students, recalls asking her departmental administrator for two inches of wire to hold her thermometer in place: “He looked in his account books and bellowed, ‘I gave you two inches of wire three months ago. What have you done with it?’”

Nevertheless, Hodgkin pursued her remarkable work over a long career – and, as a teacher and role model, created a ‘family tree’ of four ‘generations’ of woman scientists who went on to research vitamin B12 over a time period of more than 60 years.

In sketching the early decades of work on the structure of vitamin B12 and the influence of Dorothy Hodgkin, I have tried to show the human face of science. Its practice reveals so much of the best in people; it is driven by intellectual curiosity, the pursuit of excellence, and the desire to relieve

Histidine

‘Tail’ buried in protein

Protein

Above: Diagram of a fragment of the enzyme called methionine synthase (drawn by Martha Ludwig) containing methylcobalamin (colours as in figure on p. 35). The protein is represented in turquoise. A histidine group from the protein is attached to the cobalt atom. The organic base or ‘tail’ of the methylcobalamin is detached from the cobalt atom and buried in the protein. (See also final section in Fact File, p. 37.)

Below: ‘Family tree’ showing some X-ray crystallographers who worked on vitamin B12 or its derivatives. Dorothy Hodgkin looked after her students with such care and attention that she was affectionately known to some of them as ‘Mother Cat’. The first generation to follow her consisted of her doctoral students, who worked on vitamin B12 and related molecules. One of them, Jennifer Pickworth Glusker, subsequently researched the X-ray crystallography of the vitamin for over 40 years. The second and third generations included Miriam Rossi, Glusker’s research associate, and Rossi’s student, Catherine Drennan, who elucidated the structure on an enzyme fragment bound to B12.

the suffering of humankind. Science depends on cooperation among people in groups and on healthy competitiveness. Hodgkin made a great contribution to science, not only in her achievements but in her leadership, integrity, and kindness. In the words of Albert Schweitzer (quoted by Max Perutz), “Example is not the main thing in influencing others, it is the only thing.” Dorothy Hodgkin’s shining example lives on4. ■ Dr Susan M. Chemaly is in the Department of Pharmacy and Pharmacology, Faculty of Health Sciences, at the University of the Witwatersrand. She has been researching aspects of vitamin B12 for 30 years.

For more information, consult the following. G. Dodson, J.P. Glusker, and D. Sayre (eds.), Structural studies on molecules of biological interest: A volume in honour of Professor Dorothy Hodgkin (Clarendon Press, Oxford, 1981), which contains the quotations from J.P. Glusker, M. Perutz, D.P. Riley, and J.H. Robertson; G.A. Jeffery, “Nobel Prize for Chemistry awarded to crystallographer”, in Science, vol. 149 (1964), pp.

748–749; G. Ferry, Dorothy Hodgkin: A Life (Granta, London, 1998); G. Dodson, Dorothy Mary Crowfoot Hodgkin, O.M.: A biographical memoir (The Royal Society, London, 2002); P. Fara, “Pictures of Dorothy Hodgkin”, in Endeavour, vol. 27 (2002), pp. 85–86; D.C. Hodgkin, “The X-ray analysis of complicated molecules”, in Science, vol. 150 (1965), pp. 979–988; J. Stubbe, “Binding site revealed of Nature’s most beautiful cofactor”, in Science, vol. 266 (1994), pp.

1663–1664; and C.B. Perry and H.M. Marques, “Fifty years of X-ray crystallography of vitamin B12 and its derivatives”, in South African Journal of Science, vol.

100 (2004), pp. 368–380.

4. I am one of many researchers worldwide who was inspired by Dorothy Hodgkin. I never met her, but enjoyed hearing stories about her from my doctoral supervisor, John Pratt, who studied at Oxford University.

Although I do not have her special insight into the structure of molecules, I share her interest in vitamin B12 and have benefited from the knowledge and techniques that she generated.

Dorothy Hodgkin 1910–1994

Jenny Pickworth (Glusker) D.Phil 1955

M. Jennifer Kamper D.Phil 1960

David H. Dale D.Phil 1962

Frank H. Moore D.Phil 1967

C.E. Nockolds D. Phil 1967

Eric D. Edmond D.Phil 1970

H.R. Harrison D.Phil 1970

Miriam Rossi

Catherine Drennan

36 Quest 3(4) 2007

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n 0

Q Fact file

X-ray crystallography and vitamin B 1 2 Some terms In the words of Isaac Azimov: “A crystal is a solid with a neat geometric shape, with its plane faces meeting at characteristic angles, and with a characteristic symmetry. This visible regularity is the result of an orderly array of atoms making up its structure.” The crystal consists of identical unit cells (made up of atoms, ions, or molecules), linked together in a characteristic, three-dimensional pattern, or crystal lattice.

Determining the crystal structure of a substance means working out the geometrical arrangement of the atoms, ions, or molecules that form the unit cell as well as the lattice pattern that links the cells in the crystal. (Crystals of the same substance grow so that they have the same angles between their plane faces, though the crystals may not all look the same, as different faces can grow at different rates under different conditions.)

The purpose of working out the structure of a substance comes from the fact that what molecules can do follows directly from their structure (that is, ‘function follows form’). Determining the structure, then, creates the basis for understanding how the substance might behave in the body and, therefore, how best to harness its uses. Structures are crucial to the work of pharmacologists and scientists in designing new drugs that attempt to cure ailments more efficiently.

The process of determining the crystal structure of a substance is complex. One would normally work out the lattice pattern, and also the dimensions of the unit cell – that is, its size and shape. Then one would take up the challenge of determining the exact internal arrangement of the components of the unit cell itself.

X-ray crystallography uses X-ray diffraction to determine the structure of crystals and molecules.

In this technique, a beam of X-rays is directed at a crystalline sample. The electrons in the atoms diffract (or, bend) the X-rays, and the pattern of spots made by the diffracted X-rays is recorded on a photographic plate. The positions and intensities of the spots give the information that’s needed to work out the crystal structure (that is, to determine their relative positions in the crystal lattice).

Creating and reading an X-ray diffraction pattern If you stand at a window and look through a net curtain at a street light in the distance, you’ll notice that the light from the street lamp breaks up into a pattern of spots in the shape of a cross. The phenomenon is known as the diffraction of light: in this case, the small mesh of the net curtain has scattered (or, diffracted) the light waves, forcing them to change direction.

These scattered light waves reinforce one another in some directions to produce spots of light, and, in other directions, they cancel one another out to produce darkness (this is called positive and negative interference, respectively).

The scattering occurs because the distance between the threads making up the grid of the net curtain is very small. Using the pattern of the light spots as your starting point, you can determine the two-dimensional pattern of the mesh of the net curtain. If you imagine the street

Determining the structure of a crystal Many of the first X-ray crystal structures of molecules were determined (in the late 1920s) using completely flat molecules. These had to be carefully aligned in the beam of X-rays so that their structure could be determined in two dimensions.

To determine the structure of a crystal in three dimensions, it’s necessary to measure, separately, the intensities, and the directions of the X-ray beams after they have passed through the crystal, as well as the interactions among the Xrays that have been scattered from the different layers of the crystal. This scattering factor causes most of the difficulty in determining the structure of the molecules of a crystal.

The measurements then need to be combined mathematically, using a process called Fourier transformation. In the days before computers, this involved months of tedious calculation using an adding machine. The result of these calculations is known as an electron density map, which looks rather like a contour map showing mountains and valleys – the ‘mountain peaks’ represent the atoms in the molecule and show their location within the molecule.

Diffraction through a net curtain.

Cobalt and vitamin B12

Above: A night scene, showing lights.

Hodgkin’s excitement on being told that vitamin B12 contained an atom of the ‘heavy metal’, cobalt, was because it would give a high peak in an electron density map, and in this way help in determining the X-ray crystal structure of the vitamin.

The vitamin B12 molecule is different from those of other vitamins, as it is the largest of them all, and the only one containing a metal atom (cobalt).

Cobalt is a shiny, greyish metal, found in the middle of the periodic table (atomic number 27), close to iron, manganese, nickel, and copper – all of which are important in biology. Its name comes from the German kobold, which means a devil or goblin. It was so named by miners because they thought it worthless and because it interfered with the extraction of more valuable metals (such as silver, copper, and nickel) from their ores.

My own vitamin B12 research has focused on the cobalt at the centre of the molecule and on the way in which the cobalt affects the properties and reactions of the molecule.

Sometimes, in frustrating moments, when I get strange or unexpected results or the experiment goes wrong, I find myself imagining that the vitamin B12 molecule has a little goblin sitting in the middle, interfering with my work!

Below: Close-up of the light, taken through a net curtain. lamp as a source of X-rays and the net curtain as a crystal, then you have X-ray diffraction.

In 1912, the German physicist Max von Laue discovered that crystals diffract X-rays – in other words, that crystals scatter X-rays in the same way that a small mesh scatters beams of light. Realizing that the atoms in a crystal caused the diffraction of the X-rays, the British father- and-son team of William and Lawrence Bragg developed the method of determining the structure of crystals by X-ray diffraction.

The X-ray diffraction pattern from a crystal can be photographed. The wavelengths of X-rays are of comparable magnitude to the distances between atoms in a crystal, and the diffraction pattern shown in the photograph can be related to the distances between the atoms.

The intensity of the spots in the photograph depends on the number of electrons belonging to an atom and can be related to the kind of atom present in the crystal. Small and light atoms give spots of low intensity; larger and heavier atoms give brighter spots.

Unlike a net curtain, a crystal is a threedimensional solid, which makes the interpretation of the X-ray diffraction pattern more difficult. If you imagine a crystal as many layers of mesh piled one on top of another, the atoms in the crystal correspond to the threads, and the distances between atoms correspond to the holes in the mesh. Thus an X-ray beam can hit an atom in one layer of a crystal, causing scattering, and then pass on to an atom in another layer of the crystal and hit that, also causing scattering, and so on – the resulting diffraction pattern is extremely complex.

Vitamin B12 coenzymes A coenzyme is an accessory or ‘helper’ for an enzyme, which is a protein that catalyzes (speeds up) a chemical reaction taking place in a living creature. In humans, the coenzyme forms of B12 are involved in the actions of only two enzymes, with the jaw-breaking names methylmalonylcoenzyme A mutase and methionine synthase (see picture above, p. 36). Bacteria have many more B12 enzymes, including ribonucleotide reductase, which is essential for their reproduction. ■

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Viewpoint Q

Annette Combrink gives her views on what it takes to be a woman researcher in South Africa today.

I

n August, in the month of the woman, it’s good to celebrate women and science and the many excellent things that happen when they involve themselves in serious academe.

It has for a long time been a truism that, in all fields, women have to work harder and longer to achieve what men seem able to reach with far less effort – and that women still come up against a (seemingly) impenetrable glass ceiling.

How true is this, and if true, to what can it be attributed? In many years spent in academe, I have often been worried about the role of women and the way in which early promise shown by women often seems to peter out, not allowing them to fulfil it in the long term. At graduation ceremonies (and it seems that what happens at one standard university in the country is to some extent a microcosm of what happens more widely in the country and in the world at large) the winners of the academic prizes increasingly are woman students. Their excellent profiles make the audience gasp and cheer, when their curricula vitae are read out, for the sheer scale of their achievements – the distinctions liberally sprinkled throughout their degrees and awesome successes in other activities casually interspersed. The young women who appear on stage to receive their awards are good-looking, well groomed, self-

assured, and apparently on top of the world.

Why then, in academe, do we find the statistics we do for the outputs of men and women in research?

Rallying cries

‘A woman wh o wants to be the equal of a man has no ambition.’

‘The best man for the job is a woman.’

What the numbers say One measure used in South Africa for scientific excellence is a ‘rating’ from the National Research Foundation (NRF). Overall in the country, these ratings for men and women show an upward trend, but nevertheless seem not to correlate very positively with gender demographics and the fact that,

worldwide, there are 52% women and 48% men! It is encouraging, however, to note the upward trend, and the rate of this improvement.

Take a further statistic: in 2005, there were 206 rated female grantholders at the NRF (just one measure, true, but a good barometer of what happens

South African woman authors of research articles as a proportion of the total number of authors, by field Scientific field

Women who authored research articles in South Africa (%) 1990–1992

2002–2004

Agricultural sciences

14

24

Biological sciences

15

25

Chemical sciences

10

19

Earth sciences

15

25

9

13

Mathematical sciences and ICCT Physical sciences Multidisciplinary sciences

7 22

6

11

Basic health

20

30

Clinical health

14

27

NRF-rated woman researchers as a proportion of total NRF-rated researchers at South African higher education institutions

Public/Community health

26

50

Economic and management sciences

11

21

Education

27

50

Psychology

29

26

Year

Numbers (women/total)

Sociology & related studies

27

34

Other social sciences

32

33

2002

227/1267

18

Language and linguistics

29

38

2003

271/1324

20.5

Law

24

29

2004

308/1357

22.7

Religion

4

9

2005

359/1552

23

Other humanities and arts

21

26

2006

397/1604

24.7

Source: J. Mouton, “Human Capital and the South African Knowledge Base”, report to the Research Directors’ Forum Workshop, 30 May 2007, at the Centre for Research in Science and Technology, University of Stellenbosch

Source: National Research Foundation

38 Quest 3(4) 2007

Women %

Engineering & applied technologies

5 13

Q Viewpoint generally). This contrasts with the 700 rated male grantholders – and brings the proportion of women in this category to the grand level of just 22.7%. In the same year, the proportion of female ‘principal’ grantholders (in other words, the individuals cracking the whip, as it were, in research projects, both rated and unrated) was 34.5%.

Another statistic that does not reflect well on the fairer sex is the one dealing with the proportion of women who publish articles in peerreviewed research journals accredited by the Department of Education as earners of university subsidy. Over a long 14-year period (1990–2004), the situation was discouraging.

In terms of the total picture, proportionally speaking, it would seem that women are simply not fully there when it comes to research and publications, when they are measured in the terms normally used. Intriguing, though, is the distribution of women’s achievement in certain fields. Women do seem to be advancing more in those where ‘people skills’ are more important – in other words, they do better in public and community health, in education, and in sociology generally.

Although the unkind ones amongst us suggest that these are the ‘softer’ options, the other side of the coin is that they do well because of their superior emotional intelligence and because they are credited with stronger intuition – a quality that is much maligned and underestimated in the rigorous leftbrained (male) world of academe.

Strangely (or not?) they fare worst in the fields of physical sciences and religion (lingering shades of patriarchy?).

What next?

So – should one encourage one’s daughter or niece or protégée to enter the realm of academic research, particularly in the sciences?

The obstacles facing women in academe are pretty much the same obstacles that face women in other work situations (in which, dare one say it, women are sometimes also their own worst enemies).

Women start out so well in the field of academe – then where do they go?

A curious question arises – do women really want to shine in the academic field to the same extent as men? Or do they find more gratification in other fields of work where they move increasingly into the limelight, especially in the areas of management?

Over time I have reached the

How things have changed In a devastating comment on fields considered appropriate for women, a UK Royal Commission stated in 1877: “English literature might be considered a suitable subject for women ... and the second- and third-rate men who ... become schoolmasters.” Quoted in Terry Eagleton, Literary Theory, an introduction (Oxford, Blackwell, 1983).

conclusion that a woman really wanting to make it as a researcher (and in academic work generally) has to have certain qualities. She has to ■ have a passion and a sense of commitment that will carry her through in the face of prejudice and many obstacles ■ have ferocious determination (but linked to a genuine sense of humour and irony, please!)

■ keep on and keep smiling (not too much, though – that might show lack of seriousness) ■ be able to juggle all the competing demands on her.

It helps if she has boundless energy and good health.

She might, of course, simply want to do other things (first) and then go into academe (a career path that is increasingly recognized, and supported by, amongst others, the NRF L-rating for ‘latecomers to research’). Women are simply programmed in such a way that they have to get more things done – biology has the habit of being an irresistible force, ensuring the propagation of the species before such mundane considerations as splitting the atom and formulating abstruse notions of deconstruction.

Would I then encourage young women to go into research or academe in general?

YES. A woman has the right to want it all and have it all. In many instances this involves a marriage or an enduring relationship, children, other family concerns, a household and everything that goes with it. And a woman has been genetically designed to be able to do the octopus thing – as witness some recent advertisements on television showing the professional woman coming home, carrying briefcase and flowers, flitting elegantly round the kitchen, cooking, checking things – while husband sits on sofa hunched over ads on laptop, indicating that he is exhausted while gracefully deigning to accept supper (it helps semiotically that

the man playing the role of husband is also the actor doing “Groet die grotman”, the Afrikaans version of the “Enter the Caveman”!).

Why do I say ‘yes’ so emphatically, apart from the fact that a woman can and should do what she’s good at?

There is nothing quite as exhilarating intellectually as engaging in a quest for new knowledge – as pursuing to its logical conclusion something that one has intuited, that one knows should and can be pursued. There is no real difference, to my mind, between a man and a woman engaged in this absorbing search for the grail, in this bending of one’s brain towards the prize.

Women do have obstacles to overcome (some, unfortunately, of their own making – ‘acting like a woman’ in a man’s world is, while not wrong, not altogether conducive to tolerance from some males!). Women also do have to try harder and sacrifice more. But, as emerges from the statistics, they can do this, and increasingly they are doing it.

It is also true that, in research, the playing field for a woman with talent and the desire to do well can be levelled far more effectively than elsewhere, for in a real sense one is more invisible. One’s femaleness tends to disappear in a lab, or behind a desk and computer, or even in the field doing trials and digging up things.

I am convinced that future generations of woman researchers will find it easier to engage in research and be accepted, as well as to reach the dizzy heights that many trailblazing women have succeeded in reaching – through nothing else than the perseverance and commitment they have already brought to so many activities, and which they can now bring to the world of research.

Pursue this dream, I therefore say – demand more equality to be able to dedicate yourself fully enough to find the grail. It is there, and finding it is wonderful. ■ Professor Combrink is the Rector of the Potchefstroom Campus of North-West University. She taught English at high school level before joining the Department of English at the then Potchefstroom University for Christian Higher Education – then made history by becoming the first woman dean in the university and, thereafter, the first woman rector (and the first non-Dopper in that position).

Quest 3(4) 2007 39

Letters Q

Letters to Future scientists for South Africa

T

hank you for Quest. It contains articles on aviation and space and we receive it from the National Youth Development Trust. We work as a team on our science projects, and we use information we find in your magazine.

We believe commitment is important for successful projects. We want to become engineers and would like you to publish more on engineering. Our group, the Solomon Mahlangu Secondary School Aviation study group, won the 2007 Model Jet Aircraft design competition. It was an amazing competition as it brings the realization that we can succeed in doing the things we want to do as future engineers. We want to go the extra mile to become successful.

France Malatje (Team Spokesman), Solomon Mahlangu Secondary School, Mamelodi

I

have a dream that South Africa can become one of the best countries in science in the world.

There are many talented people in South Africa who are lost because they leave the country, as they believe that do not have opportunities here, and because of the fact that the country is small and still developing.

My generation are the scientists who can develop our nation – we want to work for it, and also for the world. We cannot do it alone, and we need help from universities and the government.

In our country we plan a World Cup for Soccer for sport in 2010. We plan the Gautrain for transport. But we are slow in planning for space for South Africa.

We can do it successfully with the help of other countries. I am ready to contribute towards space for South Africa even though I am a member of the future generation of scientists. I have a passion for astronomy and I want to be a senior lecturer at a university one day. I believe that I can become a Nobel Prize winner.

It is my dream to meet the Minister of Science and Technology and share my passion with him.

Wanga N.G. Ngaleka (Grade 11), Eketsang Secondary School, Germiston Address your letters to the Editor and fax them to (011) 673 3683 or e-mail them to editor.quest@iafrica.com (Please keep letters as short as possible. We reserve the right to edit for length and clarity.)

News Q Fighting junk food Healthy eating habits are hard to develop in children who are surrounded by junk food at home, at school, in shops, and in advertising. Low intake of fruit and vegetables causes about 19% of the world’s gastrointestinal cancers, about 31% of coronary heart problems, and 11% of strokes. But it’s difficult to convince American and British children to eat healthy food.

A new programme, “Food Dudes”, seems to be succeeding where others have failed. Its storyline shows superheroes Charlie, Tom, Raz, and Rosso on a mission to save the world from General Junk, who plans destruction by stealing the world’s fruit and vegetables. But the ‘food dudes’ have superpowers that spring into action when they eat the right foods. They hope to save millions of real children from early death through cancer, heart disease, and diabetes.

The programme has started weaning children off unhealthy foods that are high in saturated fats, sugar, and salt, onto foods that they often don’t at first enjoy eating but that are good for them.

It draws on psychological research. First, it encourages children to eat small quantities of good food often enough to develop a taste for it. Second, videos

expose children to superhero role models whose power comes from eating fruit and vegetables and whom they are happy to copy. Third, there’s a small reward, such as a sticker, every time the children taste fruit or vegetables.

The Irish government is implementing the programme nationally, and the UK is starting pilot trials, helped by the recent ban on junk-food advertising around TV programmes directed at children aged 4–9 years. It’s expected not only to bring about a generation of healthy children but also to save on the skyrocketing costs of treating diet-related diseases. Reported in New Scientist (21 July 2007)

Talking heads Do men or women talk the most? Verbosity seems greater in extroverts than introverts rather than being connected with gender, as was previously thought. Recording snippets of conversation among American and Mexican students, a team from the University of Texas revealed that the men scored about 16 000 words a day – the same number as the women – but there was great variation. Extroverts babbled their way through more than 24 000 words, while introverts registered about 8 000. Reported in “Awards for eloquence and silence evenly divided” in New Scientist (14 July 2007)

Careers in S&T Q

Studying astrophysics for related careers

T

he Astronomy Department at the University of Cape Town (UCT) offers the only full taught undergraduate degree in astrophysics in South Africa (for details visit http://mensa. ast.uct.ac.za). It does not limit you to a career in astronomy, but gives a solid basis for other graduate studies in science, technology, or engineering. It also prepares you for job openings in areas related to astronomy, such as instrumentation design, software development, digital processing, computer science, telecommunication, laboratory work, teaching, science education and writing, and even business.

40 Quest 3(4) 2007

If you want to become an astronomer, the bachelor’s degree in astrophysics is a strong foundation for postgraduate studies, such as the National Astrophysics and Space Science Programme (www.star.ac.za) based at UCT, with a subsidized honours and master’s programme.

The shortage of local astronomers means that there are good employment prospects in an academic career in astrophysics, particularly in South Africa. International agreements also provide doctoral and postdoctoral opportunities at partner institutions.

– Renée Kraan-Korteweg, University of Cape Town

Q Your Q uest ions answered

Gums, badgers, & economics QUESTION

What impact will the disappearance of invader plants such as the blue gum have on nature, honey badgers, and honey production, and thus the economy of South Africa?

Question from Ankie Malan.

ANSWER This many-faceted question does not have a simple answer, and has already generated much debate among beekeepers and conservationists. Exploring it illustrates the complexity that faces ecologists who are asked to advise on such issues.

Part of the answer is that gums trees (in the genus Eucalyptus, from Australia) are not set to ‘disappear’ (even if some people wanted them to). Gums form an important component of the forest industry and, at last count, they covered over 540 000 ha in formal plantations in South Africa. They are also found in many other plantations not captured by the forest industry’s statistics, as well as in thousands of woodlots and other plantings across the country. A crude analysis of the extent of these non-forestplantation gums in South Africa came up with a figure of 2.5 million ha in 1998.

With the notable exception of Red River gum (Eucalyptus camaldulensis), however, gum trees are not exceptionally invasive and can be relatively easily controlled.

Clearing efforts therefore aim to remove gums from specific areas only, such as along rivers where they use too much water, or in nature reserves where they compete with native biodiversity. Many hundreds of thousands, if not millions, of hectares of gums will remain a feature of our rural landscapes for a very long time.

The impacts of invasive alien plants on ‘nature’ are well documented. Suffice it to say that they are the second most powerful threat to native biodiversity after direct habitat destruction. However, the effect of removing gum trees – on honey production and on the South African economy – is also a complex one.

Honey production is a minor part of the story. The true value of managed honey bees lies in their use as pollinators of deciduous fruit orchards (mainly apples and pears). The deciduous fruit industry, centred in the Western Cape, is valued at around R3 billion annually. During the flowering season, beekeepers sell their pollination services to fruit farmers by moving hives into the orchards. Without

these services, annual fruit production would drop drastically – by R1.8 billion according to one estimate. When they are not pollinating fruit orchards, the bees spend up to 75% of the time foraging on gum trees. They are thus highly dependent on gums, and without these trees, the numbers of bees could become low enough to reduce deciduous fruit production very seriously.

A further complication is that the Cape honeybee (Apis melliera capensis) has become an invasive pest in other parts of South Africa and beyond. In an attempt to limit the risk, beekeepers are not allowed to transport bees in or out of the Western Cape. It is therefore not an option, for example, to move bees to distant sites at times of the year when forage is scarce in the Western Cape. So the domestic bee population is ‘captive’ in this area, where it relies on gums for survival during the offseason. Removing the trees could therefore have significant economic consequences.

But care is needed when expressing economic impacts in terms of the value of the industry because there are alternatives to bee pollination. Hand pollination is possible, for instance, but more expensive, making profit margins lower, yet still potentially keeping the industry alive.

Finally, if fruit production did become non-viable, the land could be put to other use, with alternative economic benefits.

A sound economic analysis of the entire question would be needed to measure and understand all these trade-offs.

The effects of honey production on ‘honey badgers’ (Mellivora capensis) may at first seem beneficial, because badgers should profit from increased supplies of food in the form of bee larvae and honey from hives. In reality, however, badgers’ predilection for feeding on the grubs of bees puts them in direct conflict with beekeepers, many of whom, unfortunately, kill badgers to protect their assets. The Endangered Wildlife Trust has initiated a campaign, supported by pressure from honey retailers and consumers, to label honey as ‘badger friendly’. Leading

retailers such as Woolworths and Pick ’n Pay have committed themselves to selling only badger-friendly honey. To comply, beekeepers must use non-lethal means to protect their hives and are audited annually. The net effect of a honey industry (which depends on gums) on badgers is thus changing from negative (killing of badgers) to neutral (leaving them alone where they fend for themselves without affecting honey producers).

Considering the economic benefits of gums to South Africa as a whole, the question becomes even more complex.

Besides their link to the production of deciduous fruit, they also confer significant advantage on South Africa’s forest industry (half of which is based on gums) that produces timber valued at about R4 billion annually. This in turn is processed (as sawn timber or pulp), and supports exports valued at R9 billion per year. But forestry comes at a cost. Forest plantations use significant amounts of water – over 1 billion m3 per year – for which they are obliged to pay ‘streamflow reduction’ costs in terms of South Africa’s water law; pulp mills also cause environmental pollution … and so on.

The net value of the forestry industry (in terms of benefits and costs) is a subject of ongoing debate, is often highly politicized, and deserves further study.

In the end, even if a question such as the one asked here seems simple enough, there are no simple answers. The options that we finally settle for represent a compromise that society has to make.

Scientific examination of such issues, within a framework of ecological economics, is becoming more and more important in providing sound operational solutions. ■ Dr Brian van Wilgen, Centre for Invasion Biology, CSIR, Stellenbosch E-mail your questions to the Editor (write S&T QUESTION in the subject line) at editor.quest@iafrica.com OR fax them to (011) 673 3683. Please keep questions as short as possible, and include your name and contact details.

(We reserve the right to edit for length and clarity.)

Quest 3(4) 2007 41

ASSAf News Q

Top researchers newly elected to the Academy Eight woman researchers are among the eighteen new members of the Academy of Science of South Africa (ASSAf), the national ‘brains trust’ that forms part of an international network of close to 100 partner academies.

The eight women are: psychiatrist Soraya Seedat, who co-directs the Unit on Anxiety and Stress Disorders run jointly by the University of Stellenbosch and the Medical Research Council and who has a particular interest in post-traumatic stress disorder in children and adolescents; virology professor Estrelita Janse van Rensburg at the University of Pretoria whose research ranges from work on HIV to combating viruses that infect the lungs and cause lower respiratory tract diseases; atmospheric scientist Roseanne Diab, from the

school of environmental sciences at the University of KwaZulu-Natal, whose work on pollution includes research to understand the ozone layer, and measuring the amount of ultraviolet radiation, a key cause of skin cancer; research programme manager Shamila Nair-Bedouelle from the directorate-general of the European Commission, who manages a programme to identify new and emerging trends in science and technology; medical doctor and paediatrician Glenda Gray, associate professor in the Perinatal HIV Research Unit based in Soweto at the Chris Hani Baragwanath Hospital and run by the University of the Witwatersrand; education professor Sarah Howie, director of the Centre for Evaluation and Assessment at the University of Pretoria, and instrumental in providing data on South African teachers’ and students’ inadequate understanding of maths and science and in finding solutions; Helen Rees, who directs

the University of the Witwatersrand’s Reproductive Health and HIV Research Unit in Soweto at the Chris Hani Baragwanath Hospital; architecture professor Vanessa Watson from the University of Cape Town, who has a special interest in making the postapartheid cities of South Africa user-friendly for the poorest of the poor.

"The Academy includes the country's most active scholars in all fields of scientific enquiry," says Academy president and University of Pretoria vice-principal Robin Crewe. The ten-year-old organization is intended to be "a collective national resource, making it possible to generate solutions to national problems based on the best available evidence."

The ASSAf now has 276 members, distributed over the entire spectrum of scientific scholarship in the country. Over a third of them are black and nearly a quarter are women.

gather volunteers from around South Africa to help with humanitarian programmes. The nature guide courses prepare young people for positions as nature guide. Completing the one-year course leads to the National Certificate in Tourism Guiding. The JGI SA Chimpanzee Sanctuary training course, covers chimpanzee behaviour and the management of primate sanctuaries.

Visit www.janegoodall.co.za. For more, and to eceive the Roots & Shoots newsletter, e-mail info@janegoodall.co.za.

“Why Viruses continue to threaten our Lives”,

by Nobel laureate David Baltimore, at 12 noon at the University of the Witwatersrand, Johannesburg. Visit www.africagenome.co.za.

24 The last of the Darwin lecture series is by Jonathan Rees, “The importance of being red!” on the phenomenon of red hair and fair skin, and the genetics of hair and skin colour, in particular sun-sensitive skin. Information at www.africagenome.co.za or phone Adielah van der Schyff at (021) 406 6297.

Botanical Society of South Africa (Bankenveld Branch) (WSNBG): Tswaing Crater visit with Nick Grober and G. Bredenkamp (13 Oct, meet at 07:00 at Garden or 09:00 at the Crater); “Spiders” talk & walk with Astri Le Roy (27 Oct at 09:00, Nestlé Environmental Education Centre, WSNBG). Book with Karen by phoning (011) 958 0529 or e-mail botsoc@sisulugarden.co.za.

■ November 28–30 10th Annual SAASTEC Conference, “Science Centres and Sustainable Living – does your life style cost the earth?” Information at www.saastec.co.za, or phone (035) 340 2409 / 082 320 0538 or e-mail Karen@profilepr.co.za.

Diary of events Q Shows ■ Iziko Planetarium, Cape Town Visit the new show, “Living inside the Cosmic egg”, 1 August until year-end. It describes an opaque ‘wall’ surrounding the observable Universe within which exist billions of galaxies.

Screenings Mon-Fri at 14:00 and weekends at 14:30; additional screenings Tue at 20:00 followed by a Sky Talk on the current night sky.

(No screening on 3 Sept.) Phone (021) 481 3900 or visit www.iziko.org.za.

■ South African Astronomical Observatory (SAAO), Cape Town The SAAO is open to the public on the second Saturday of each month at 20:00. Details of events and on tours to Sutherland at www.saao.ac.za/public-info/visits.

■ Pietermaritzburg ScienceUnlimited, Royal Agricultural Show Grounds This science education project has been expanded to KwaZulu-Natal. Join in 28–31 August. Details at www.scitech.co.za.

■ MTN ScienCentre, Cape Town Visit the Marine Biosciences Mini-Exhibition during August. For details and other events, phone (021) 529 8100 or visit www.mtnsciencentre.org.za.

Get involved ■ Hike Walk 380 km from Eden to Addo Elephant National Park in 18 days, 5–23 September (or join for part of the way), crossing five biomes, seven mountain ridges, six nature reserves, and a World Heritage site. Visit www.edentoaddo.co.za or e-mail hike@edentoaddo.co.za.

■ Clean up Support the anti-litter campaign at the Johannesburg Zoo in association with the Jane Goodall Institute South Africa (JGI SA) and Community Connect from 24 August.

Hundreds of schoolchildren will be bussed to the zoo to help clean up, and one day’s litter will be exhibited in a cage for all to see. Contact Gaby Sidley on 083 299 9291 or e-mail gaby.sidley@gmail.com.

■ Train Jane Goodall Institute South Africa Roots & Shoots and John Cussons from Untamed Africa

42 Quest 3(4) 2007

Lectures & conferences ■ August 29–31 1st African Union Women in Science conference: The Forum, Bryanston, Johannesburg. Information at www.africa-union.org or www.dst.gov.za.

■ September 10 Launch of the Cape Town Component of the International Centre of Genetic Engineering and Biotechnology (ICGEB) at the Institute for Infectious Diseases and Molecular Medicine at the University of Cape Town. Information at www.icgeb.trieste.it or www.dst.gov.za.

17–19 Annual Bio2Biz Conference, at the Cape Town International Convention Centre, to promote the advances of biotechnology in the context of global achievement. Information at www.bio2biz.org.

Botanical Society of South Africa (Bankenveld Branch) (WSNBG): “Reptiles” talk by herpetologist Graham Alexander (8 Sep at 10:00, Nestlé Environmental Education Centre, WSNBG); “Free-Me (Organization rehabilitating lost and wounded wild animals)” by Margie Brocklehurst, (15 Sep at 09:00, BotSoc Boardroom); Bird Spotting Walk with Ella Jansen van Vuuren (23 Sep, meet at Garden main entrance at 06:45 for 07:00); Children’s Orienteering Programme with Karen Carstens and Ella Jansen van Vuuren (28 Sep, meet at Garden main entrance at 09:00). Book by phoning Karen at (011) 958 0529 or e-mail botsoc@sisulugarden.co.za.

■ October 5 Annual Nelson Mandela Science Lecture,

Opportunities ■ Unemployed science, engineering, and technology graduates can join an information hub and link up with employers by registering on the database of the South African Graduate Development Association (SAGDA). Visit www.sagda.org.za.

■ Free gym instruction for 20 selected talented young Cape athletes from disadvantaged backgrounds: an offer by Body Excel gyms in Cape Town. Contact Leanne Raymond by phone at (021) 462 0416 or fax at (021) 462 0427 or e-mail leanne@hwb.co.za.

Diarize ■ September – Origins month ■ October – Astronomy month ■ World Space Week – 4–10 October (visit www.worldspaceweek.org) ■ SciFest Africa, Grahamstown – 16–22 April 2008 (visit www.scifest.org.za)

Q Q uest crossword

Q News How elephants run Elephants go from walking to running at surprisingly low speeds. Early evidence that these animals could run came from John Hutchinson and colleagues at the Royal Veterinary College, London, in 2003, who recorded Thai elephants reaching top speeds of 25 kilometres per hour. A follow-up study in UK safari parks of elephants tagged with motion sensors showed them shifting to a running gait once they got to 8 kilometres per hour. Above this speed, they used their back legs like ‘pogo sticks’ to move their bodies forward over their stiffer forelimbs in a vaulting motion. Reported in Nature (5 July 2007)

You’ll find most of the answers in our pages, so it helps to read the magazine before doing the puzzle.

Ozone threatens carbon sinks As levels of atmospheric ozone pollution rise during the 21st century, the ability of plants to serve as a vital carbon sink will drop, says a new climate-modelling study.

Ozone high up in the stratosphere shields Earth from solar ultraviolet rays, but, reports Stephen Sitch of the UK Met Office’s Hadley Centre for Climate Prediction and Research in Exeter, too much of it at ground level can poison plants and reduce their ability to photosynthesize. Ozone forms when oxides of nitrogen – mainly from vehicle exhausts and fossilfuel power stations – react with other airborne chemicals.

Already, many of the world’s most polluted areas suffer from ozone concentrations above 40 parts per billion, which are enough to damage plants. Nearly all the populated parts of Earth are predicted to exceed this threshold by 2100.

Plant growth is a crucial carbon sink (see the insert following p. 22).

According to the researchers’ calculations, in 1901 plants were responsible for storing 113 billion tonnes of carbon worldwide. By 2100, this figure is predicted to rise to 171 billion tonnes – but, they add, without ozone it would be more than 200 billion tonnes.

There are solutions if the problem is addressed head on. Ozone is a short-lived pollutant that occurs at regional level. The use of catalytic converters can lower ozone levels by reducing the precursors to this gas.

Reported in Nature (26 July 2007)

Beware iPods in a thunderstorm

Jemima

Across

Down

Of or relating to smell (9)

1

Form of oxygen (5)

4

Iron Age bead material (5)

2

Red blood-cell deficiency (7)

7

The one that bears and rears young seahorses (4)

3

Type of telescope in 14 Down (5)

5

Fancy motor-car (4)

8

Thin flat organ used by fish to propel and steer (3)

6

Small fish of the family Syngnathidae (8)

9

See 13 Across

1

11

Lives by preying on other animals (8)

13/9 Pipefish compartment for carrying eggs (5,5)

12

Vitamin B1 deficiency disease (4-4)

15

Waste matter carried by drains (6)

14

17

The D in CCD (6)

Galaxy named after a Dutch telescope (9)

18

Water-borne sediment (4)

16

19

Artery carrying blood from the heart’s left ventricle (5)

Heavy transition metal with colourful compounds (6)

20

22

Impoverishment of land (11)

Milky plant fluid, can be stretched (5)

24

Garden beads unique to a particular valley (6)

21

Poisonous monoxide from engine exhausts (6)

25

Colouring matter (7)

23

28

The valley referred to in 24 Across (7)

The Great Attractor seems to direct galaxies towards this constellation (5)

26

29

Freshwater fish bred in ponds (4)

30

Large brown seaweed (4)

Primitive freshwater fish, with sharp teeth, of the genus Lepisosteus (3)

27

Pasture land on a Swiss mountain (3)

10

Dirty fog (4)

How do you like the crossword puzzle?

Was this one too difficult? Too easy? Just right? Would you like more difficult puzzles as well (with prizes)? Or other kinds? Fax the Editor at (011) 673 3683 or e-mail your comments to editor.quest@iafrica.com (mark your message CROSSWORD COMMENT).

If there’s lightning outside, don’t jog with your earphones on, say Eric Heffernan and his team at Vancouver General Hospital in Canada. They had observed unusual patterns of burns on a lightning-strike patient who had been jogging with his iPod. One long burn stretched up his chest and neck to each ear, and both eardrums were badly damaged. Normally, lightning would conduct over the body, because of the skin’s high resistance. But sweat combined with the metal wiring probably channelled the current through the jogger’s ears. Reported in New Scientist (14 July 2007)

Tips for decision-makers From New Scientist (5 May 2007) come ten tips, based on psychological research, for checking the wisdom of the decisions you make. n Don’t fear the consequences – what people fear is mostly not as bad as they’d thought it would be, and the benefits of fulfilled hopes seldom come up to full expectations. n Follow your instincts – sometimes they give better information than weighing up the pros and cons. Simple choices (such as choosing the best motor car from several alternatives) are often best made after analysis, but more complex decisions seem to need a shot of instinct. n Consider your emotions – decision-making activates the limbic system (the brain’s emotional centre) and people with damage to this part of the brain are crippled by indecision, perhaps because our brains store emotional memories of past choices that inform present decisions. n Play devil’s advocate – overcome ‘confirmation bias’ by searching not only for evidence to support your favourite choice but also for evidence that can prove you wrong. n Stay focused – irrelevancies can get in the way of better judgement, especially when information is limited. n Put the past behind you – don’t hang onto a bad past decision just because you’ve already invested so much in it. n Try another viewpoint – consider how an argument is presented and whether it leans one way or another. (What does a dieter prefer, milk that is “90% fat free” or milk that has “10% fat”?) n Beware peer pressure – following the herd, or taking advice only because whoever offers it has a position of authority, doesn’t generate the best decisions. n Reduce your options – having fewer options to consider reduces the strain on your information-processing skills and can make the decision you take more satisfying. n Get someone else to choose – sometimes it’s more satisfying to hand over to someone else (for example, asking a doctor what treatment you should choose). Source: New Scientist (5 May 2007)

Quest 3(4) 2007 43

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44 Quest 3(4) 2007

Q Back page science Know this ■ “[Science is] fun the way rich ideas are fun, the way seeing beneath the skin of something is fun. Understanding how things work feels good.” – Natalie Angier, The Canon: A Whirligig Tour of the Beautiful Basics of Science (Houghton Mifflin, 2007).

■ “Knowledge is power.” – Sir Francis Bacon (1561–1626), English author and philosopher.

■ “If we value the pursuit of knowledge, we must be free to follow wherever that search may lead us. The free mind is not a barking dog, to be tethered on a ten-foot chain.”

– Adlai E. Stevenson Jr (1900–1965), US politician.

■ “If you have knowledge, let others light their candles at it.” – Margaret Fuller (1810–1850) US Transcendentalist author.

■ "No pessimist ever discovered the secrets of the stars, or sailed to an uncharted land, or opened a new heaven to the human spirit."

– Helen Keller (1880–1968), writer, public speaker, and social activist (despite being blind and deaf).

Mary, Mary, quite contrary Mary Kingsley (1862–1900) had no formal education and spent most of her short life dutifully looking after other people. (This Victorian spinster died while nursing Boer prisoners of war in Simon’s Town.) She was passionate about West Africa, which she visited twice and explored fearlessly, collecting fish specimens and learning about local legal systems and religious beliefs. She wrote two books about her travels and gave public lectures in England, but was horrified by the suggestion that she was an emancipated woman. Yet a woman journalist who interviewed her made a good point : “It is a curious inconsistency that little account is taken of a woman if she sacrifices herself on the domestic hearth, while should she follow in the track of men – frequently a much easier course – and undertake public or scientific work, everybody cries ‘How marvellous!’” Kingsley was opposed to women participating in scientific societies (from which they were mostly excluded) and said: “If we women distinguish ourselves in science in sufficiently large numbers at a sufficiently high level, the great scientific societies … will admit women on their own initiative or we shall form scientific societies of our own of equal eminence. The great thing for us in this

generation to do is show a good output in high class original work.” (From Katherine Frank, A Voyager Out: The Life of Mary Kingsley, Corgi Books, 1986.)

Still battling ■ A century after Kingsley’s death, Discover magazine (11 January 2002) had this to say: “It will take goodwill and hard work to make science a good choice for a woman, but it is an effort at which we cannot afford to fail. The next Einstein or the next Pasteur may be alive right now — and she might be thinking it's not worth the hassle.”

■ Consider the case of Dame Jocelyn Bell Burnell (1943– ), for example, who is about to become the first woman president of the UK’s Institute of Physics. After helping to build a radio telescope and using it to discover pulsars, she had to watch her thesis adviser take the Nobel prize for the achievement. Apparently he described her as "a jolly good girl [who] was just doing her job."

■ The work of physicist Chien-Shiung Wu (1912–1997) on parity violation was also not recognized. But she is credited with the remark: "There is only one thing worse than coming home from the lab to a sink full of dirty dishes, and that is not going to the lab at all."

Career advice Asked for advice for young people interested in science, spider expert Petra Sierwald (Field Museum, Chicago, USA) said: “If you feel drawn to science and research, by all means, go for it. You will need maths, at least one foreign language and a good general education. But most of all, you will need to be willing to work for years without any or very low pay and to work more than eight hours a day and more than five days a week. To be successful in such a career the joy of the research must make up for a lot of inconveniences. To stretch one’s thinking and to go with your brain where truly nobody has been before is exhilarating (almost addictive) and can be extremely rewarding. Combining a research career with motherhood will make you more vulnerable, especially since motherhood does not earn you any points. On the contrary, mothers are sometimes viewed with suspicion, as if giving birth would somehow be hazardous to your intelligence.”

Geologist Meenakshi Wadhwa noted: ”Maths is definitely very important. A lot of kids hate it, but if you honestly apply even a moderate

amount of effort, it's not very difficult at all.”

Zoologist Shannon Hackett advised visiting places to see what scientists do: “Nothing is better inspiration than talking to people and hands-on experience.”

It takes all types Every year, Popular Science magazine comes up with a list of the 10 worst jobs in science. This year No. 10 is whale-faeces researcher. But one of those intrepid types, Rosalind Rolland, says: “It surprised even me how much you can learn about a whale through its faeces …. You can test for pregnancy, measure hormones and biotoxins, examine its genetics. You can even tell individuals apart.”

The list continues: forensic entomologist (solving murders by studying maggots); Olympic drug tester (your findings will upset someone); gravity research subject (you have to lie still for weeks on end); Microsoft security worker (the tedious slog of fixing reported software problems); coursework carcass preparer (killing and preserving specimens for dissection); garbologist (sifting through rubbish to analyse consumption patterns and how quickly garbage breaks down); elephant vasectomist (it’s a big job); oceanographer (nothing but bad news); and hazardous-materials diver. An example of this last job was having to remove the body of a man who had driven his truck into a pig farm’s waste lagoon and drowned. In the pig waste were the needles used to inject the pigs with antibiotics and hormones.

Bush talks science ■ “It’s time for the human race to enter the Solar System.”

■ “It isn’t pollution that’s harming the environment.

It’s the impurities in our air and water that are doing it.” George W. Bush (US president 2001– ) Compiled by Ceridwen Answers to Crossword (page 43) ACROSS: 1 Olfactory, 4 Glass, 7 Male, 8 Fin, 10 Smog, 13/9 Brood pouch, 15 Sewage, 17 Device, 18 Silt, 19 Aorta, 22 Degradation, 24 Roller, 25 Pigment, 28 Limpopo, 29 Carp, 30 Kelp.

DOWN: 1 Ozone, 2 Anaemia, 3 Radio, 5 Limo, 6 Seahorse, 11 Predator, 12 Beri-beri, 14 Dwingeloo, 16 Cobalt, 20 Latex, 21 Carbon, 23 Norma, 26 Gar, 27 Alp.

MIND-BOGGLING MATHS PUZZLE FOR Q UEST READERS Q UEST Maths Puzzle no. 4 Consider all the numbers from 100 to 999. There are exactly four numbers where the sum of the digits cubed equals the original number. For example, 153 = 1x1x1 + 5x5x5 + 3x3x3 = 1 + 125 + 27. Another two of the numbers are 370 and 407. What is the 4th?

Win a prize!

Send us your answer (fax, e-mail, or snail-mail), together with your name and contact details, by 15:00 on Monday 17 September 2007. The first correct entry that we open will be the lucky winner. We’ll send you a cool Truly Scientific calculator!

Mark your answer “QUEST Maths Puzzle no. 4” and send it to: QUEST Maths Puzzle, Living Maths, PO Box 478, Green Point 8051. Fax: 0866 710 953. E-mail: livmath@iafrica.com.

For more on Living Maths, phone 083 308 3883 and visit www.livingmaths.com

Answer to Q UEST Maths Puzzle no. 3 The digits corresponding to the letters in the puzzle are: L = 0; P = 1; H = 2; O = 3; A = 4; E = 6; S = 7; N = 8; C = 9. The mathematical equivalent of the message, therefore, is: 83 + 12 386 + 94 007 = 106 476.

The winner is Bongani Myeza of Richards Bay.

Quest 3(4) 2007 45