6 minute read
Research
Rolling in sync
A recent study by dung beetle experts published in The Proceedings of the Royal Society shows the remarkable cooperative activity between male and female Sisyphus beetles when transporting a dung ball. It is believed to be a unique example of animals other than humans working together to move objects around without knowing their final destination.
Professor Marcus Byrne (PhD 1998) of the School of Animal, Plant and Environmental Studies at Wits, and Dr Claudia Tocco from Lund University in Sweden, who have been studying dung beetles for decades, found that pairs of beetles carefully coordinate their actions when their path is blocked or faced with a series of obstacles.
“To climb tall obstacles with their common ball of dung, the female assisted the leading male in lifting the ball by steadying and pushing it upwards in a ‘headstand’ position during the climb,” the paper reads. Their results suggest that pairs of Sisyphus beetles cooperate in such a way that the male steers and the female primarily assists in lifting the ball.
Although ants coordinate to get food to their nests, and social spiders cooperate to carry prey to their shelters, both know where they are heading and when they have arrived. With dung beetles, couples start rolling their dung balls with no idea where they will stop.
When the male is removed, the female also becomes inactive, but she can be “reactivated” by making the ball vibrate. How they communicate with each other remains a mystery. “The mechanism that allows the beetle pair to communicate and coordinate their joint actions is currently not known,” says Byrne.
Source: Royal Society
Speedbumps for growing old
The 10-year (and counting) project that has been following a cohort of 5 059 adults over 40 in the Bushbuckridge sub-district of Mpumalanga province, Health and Aging in Africa: Longitudinal Studies in South Africa (HAALSA), is one of the longest running surveillance surveys in Africa. The study is a collaboration led by researchers from the South African Medical Research Council, Wits Rural Public Health and Health Transitions Research Unit (Agincourt), Harvard University, Columbia University, the University of Cape Town and the South African Population Research Infrastructure Network. Older adults have been periodically interviewed about their health and experience of ageing and key laboratory markers and clinical measurements are assessed.
In the latest studies researchers firstly explored whether cash transfers and social grants improved cognitive health of respondents as they aged. They found that people who received the cash were better off than those who did not, showing slower ageing-related memory decline and lower dementia probability.
Researchers also examined the impact of the older person’s grant on men’s later-life cognitive health. They found that men who received the full extra years of pension income eligibility had significantly better cognitive function than expected. The additional cash transfers led to a significant reduced risk of mortality. These findings can inform health and development policies to achieve better outcomes for those ageing in South Africa and beyond.
Professor Stephen Tollman (MBBCh 1984, BSc 1979, MMed 1999), director at Agincourt, said: “The resulting evidence from HAALSA will not only convey insights from a region of the world where ageing is not well understood but can be harmonised with other studies of dementia and ageing in low-, middle-, and high-income countries, helping to shed light on the nature of ageing within a global context.”
Sources: HAALSI, The Conversation
Prof Tollman received a Gold Award at the South African Medical Research Council’s 10th Scientific Merit Awards on 7 March 2024. YouTube
Clues come in shades of pink
Researchers have found that the shade of pink flowers found in the Drakensberg at the end of summer is directly related to the amount of rainfall and sunlight the plant receives; the darker the pink flower, the more sunlight and water it has had.
Masingitla Mtileni (BSc 2018, BSc Hons 2019, MSc 2021), from the School of Animal, Plant and Environmental Sciences at Wits, was the lead author in the study of Rhodohypoxis baurii var. confecta published in Plant Ecology. According to the study single flowers of this species do not change colour over time, but some individual plants are potentially responding to changes in environmental conditions. The field data also showed that soil moisture along with an interaction between ultraviolet radiation and temperature best explained the change in the number of pigmented flowers over the flowering season. The plant produces pigments or anthocyanins to prevent tissue damage because of increased temperatures and ultraviolet levels later in the flowering season. The ratio of white to pink flowers will differ each year. The study didn’t support the assumption that a single flower changes colour over the course of the season.
Source: Nature
Unseen threat in our rivers
Dr Dalia Saad (MSc 2011, PhD 2013), researcher at the School of Chemistry at Wits, and Wits MSc student, Hadeel Alamin, provided the first data on microplastics in the Nile River in Khartoum, Sudan, published in ScienceDirect.
Africa is home to some of the largest and deepest of the world’s lakes and notable rivers, but not much is known about the extent of microplastics in the continent’s freshwaters. Microplastics are classified as plastic particles with a maximum size of five millimetres, all the way down to nanoscale. Tilapia is a popular African freshwater fish species which forms the basis for commercial fisheries in many African countries. In the 30 freshly caught tilapia fish researchers surveyed, a total of 567 microplastic particles were found, indicating the River Nile is contaminated with microplastics that can be consumed or absorbed in various ways by the tilapia and other aquatic organisms.
The results echo a similar study of the Vaal River in 2022, in which 26 carp fishes’ digestive tracts contained a total of 682 particles – ranging from seven to 51 particles per fish. Both studies are important scoping investigations for future studies and have huge health and economic implications as the rivers are crucial to agriculture, breeding livestock and recreation.
Sources: Science Direct, The Conversation
