Is Evolution Progressive?

Is Evolution Progressive?

Progress – Ben Dempster

THE MEANING OF PROGRESS The first step to discovering anything about a connection between evolution and progress is to examine our progress conception. A most important aspect of this is making distinctions; being able to differentiate between kinds of progression. Evidently, with numerous notions of progress, we will be able to more accurately portray what type of progression, if any, is inherent in evolution.

Firstly, there is a difference between general and particular or universal and non-universal progress. It must be noted here that very few academics in the field who buy into any truly universal progress. This is because universal progress would require unachievable aims.

Progress would have to occur in all times and in all situations along the evolutionary timeline 1.

Obviously, nobody takes this kind of reasoning seriously. If progress, in any positive sense, had been constantly happening to everything all the time, catastrophes like mass extinctions would be impossible to reconcile.

Hull’s paper is objectionable because it merely brings us to this point and no further. Hull surmises that there is no one direction to evolution, there are instead many 2. Because Hull addresses the common viewpoint in his attacks, he says nothing further about exactly what these multiple directions might be.

One must next distinguish net from uniform progress. Uniform progress requires constant progress from generation to generation in whatever criterion. Net progress does not require unidirectionality; rather, if the latter half of the sample size is more progressed on average than the former, net progress has occurred. Once again, net progress is a far more evidentially based and popular doctrine than uniform progress. We almost arrive at a reductio ad absurdum on many accounts of uniform progress. For example, if we considered surviving longer was a good barometer for progress, uniform progress would imply every generation would have to live longer than the one before it. This is absurd: Even the least fit individual of the following generation would still have to live longer than its parents.

Many also confuse the notions of ‘change’ and ‘direction’ with progress. Just because we can attribute a direction to evolution, (e.g. time’s arrow) we do not automatically have a progressive system. Accordingly, discovering that there has been change in evolution is not enough to support progression.

What one requires to exemplify progress is a directional change for the better 3. This means there are two elements in ‘progress’. The descriptive aspect tells us, with biological history as evidence, that directional change has happened on earth. The prescriptive aspect argues that this change has been for the better.

1

Nitecki, 1988, p. 19

2

Hull, 1988, p. 45

3

Ayala, 1988, p. 78

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Progress – Ben Dempster

In the end, the most interesting and plausible types of progress that could be candidates for what occurs in evolution are particular progress theories of net increase in one characteristic or another.

Below, different progress theories will be assessed. They fall roughly into three categories: nonbiological characteristic based, such as progress is intelligence or the accumulation of information; biologically based conjectures; and finally, because of overwhelming interest, complexity, although biologically based, deserves a category of its own.

AXIOLOGICAL PROGRESS A most obvious suggestion for progress over the course of time is the one we notice everyday – accumulation of scientific knowledge and technological prowess in the human world 4. Modern thought is quick to extinguish this objection with an assumed difference between humans and the rest of the natural world. However, we are evolutionary products and, as such, it seems ridiculous not to consider our artefacts in somewhat the same light. Consider the vast libraries worldwide and the Internet’s enormous storage. There has undoubtedly been a net increase in both the volume and complexity of human knowledge.

Yet, this is not usually what people are trying to prove when they speak of progress in evolution. Both sides of the traditional progress debate can agree that human knowledge hoarding had increased. This does not imply adherence to the more scientifically interesting and arguable thesis of a wider progress, incorporating more than just man.

Nitecki attempts to ground progress in the notion of improvement 5. He gives us the analogy of the progress made from a horse drawn cart to a warplane. Nitecki contends that we can determine progress irrespective of subjective values6. So, we can apparently decide that the warplane is a progression over the cart without such subjective values as ‘war is bad’ overruling us. The difficulty is that Nitecki just seems to be missing exactly what the subjective value employed in this decision is. We value a warplane over a cart because it is more efficacious. Warplanes transport more things over a further distance at a greater speed with more comfort. In every way, the warplane is a more efficient machine. But this doesn’t mean that the warplane is somehow objectively good, merely that I value (subjectively) efficiency and not, for example, environmental friendliness.

With regards to the common (at least in non-scientific circles) progress barometer of intelligence, a more than cursory glance will reveal this to be deeply problematic. Initially, we must decide what we count as intelligence. For the sake of argument I will use approximate scientific orthodoxy to answer this question. Humans are intelligent, primates are a little bit intelligent and some animals like pigs and dogs have a minimal amount of intelligence. As for dolphins, common mythology has it that they are as intelligent as we are.

4

Nitecki, 1988, p. 4

5

ibid. p. 21

6

ibid.

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But just how are we supposed to measure the intelligence of a dolphin? A standardised I.Q. test won’t do, dolphins lacking the appropriate writing bits. The difficulty of comparing intelligence between organisms on earth seems more difficult than the comparing of two obviously technologically advanced species. Here I have in mind humans, who are intelligent on any meaningful account, and aliens with evident technological ability. Without a bit more success from the SETI program, we have only one prominent example of intelligence to even begin to theorise about7.

The same is not true for determining purely biological difference. We have many scales that can be applied to individuals in nature like size, cell organisation and possession of various physical structures without having any of the problems that comparing the intelligences of earthly creatures does.

BIOLOGICAL PROGRESS A more promising project lies in measuring progress by some biological concept. Certainly, this approach is still somewhat theory-laden. However, intelligence measurement carries far greater risks and anthropocentric assumptions than does gauging biological mass increase, for instance.

Net increase of biomass has been reported numerous times 8. Part of the evolutionary explanation for this is that larger creatures appeared on the scene chronologically after the initially smaller creatures9. With larger creatures came larger numbers of individuals.

Yet these facts are incapable of supporting actually held progress beliefs for two reasons.

Despite the favouritism shown towards net increase shown above, we must remember that this is a very punctuated increase, with many periods of biomass decline, such as numerous mass extinctions. One ought to keep in mind that the causes of these mass extinctions should not be put in opposition to evolutionary forces. Many of the causes of mass extinctions and the lowering of biomass levels are environmental. We cannot consider the environment as merely a constraint on evolution rather than being an integral part of it; imagine what kind of impact this would have on the study of trees (the mere ‘environment’ of a forest-dweller). Therefore, the fact that mass extinctions have happened throughout evolutionary history should be taken as part of the direction of evolution. Ignoring setbacks and focussing on the abstract notion of ‘net biomass progress’ is an error.

Besides, if proving that biomass levels have increased over time was all that needed to be done, the task would be a lot simpler. The almost trivial increase of individual numbers and biomass is certainly not the interesting thesis that people mean when they talk of evolutionary progress10.

7

Raup, 1993, p. 40

8

Ayala, 1988, p. 85

9

ibid.

10

Raup, 1993, p. 45

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Species richness is another phenomenon that, according to multiple models, has enjoyed a net increase over time11. This fact is open to the same retorts as above, that the increase has major downward sections, and that these downward regions cannot be arbitrarily dismissed as not a part of evolutionary progress. But it is not true that species richness as a progress barometer is an unpopular conclusion.

Just how much it shows anything interesting, on the other hand, is unquestionably in doubt. All that a greater number of species seems to show is that evolution throws up more attempts at once during periods of increasing species rates. When a large extinction event occurs, the species rate drops dramatically again before steadily advancing as evolution again throws up more possibilities. Net progress for species rates should not be cast in a holy light; three cat varieties instead of one does not show any ‘progress’ in itself. As a concept, species rate does not have the prescriptive force to be the goal of progress. Once we move from fewer to more species types, there is still a further question as to whether this is good, and why.

INTERNALIST COMPLEXITY McShea chooses to divide complexity theories into two categories, internalist and externalist 12.

I will make the same distinction. Internal theories postulate that the reason for increasing complexity is a function of the particular organisms it happens to. External complexity is driven by natural selection; as a result of the selection pressures put on organisms, more complex organisms emerge.

There is a trivial case of progress that results from internal complexity: the move from unicellular to multicellular organisms. Yet, once again, the conclusion one can reach with such evidence is far short of any interesting progress thesis. If multicellularity is a big step up from unicellularity, we still need a way to distinguish the multicellular organisms otherwise we are left with a hypothesis of just one instance of progress – when multicellularity appeared.

Dawkins’s big contribution to this area is his discussion of co-adapted genotypes and of gene ‘teams’. The environment that any gene must be successful in is comprised of many things, a very important one of which is other genes13. Because the genetic environment requires that genes work together, we end up with chains of co-operating genes that favour extending their own chain rather than starting again.

Such co-operation, over time, could easily lead to the kind of complexity increase a progress theorist needs. After all, very little of an organism’s genome changes during any one generation – any small change, if not in harmony with the current genetic ‘majority’, will not survive. Furthermore, as Saunders and Ho note, it is easier to add components to a biological system than to delete them14. This is because, as genes are not sole agents, deleting any one 11

Hull, 1988, p. 41

12

McShea, 1991, p. 306

13

Dawkins, 1986, p. 169

14

McShea, 1991, p. 307

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gene would cause too much change, which brings a higher probability of deleterious alteration.

EXTERNALIST COMPLEXITY A prominent example of externally driven complexity increase is what Dawkins’ refers to as ‘arms-races’15. Arms races may be divided into two types, symmetrical and asymmetrical 16.

Symmetrical arms races occur when two organisms are trying to do the same thing. Forest inhabiting trees, to get vital access to the sun, need to be higher than all or most of the other plants in the forest. Because all the trees have this same goal, sunlight, and similar methods to achieve it, growing taller, there is a selective advantage to being taller than other trees. So all trees are, or have been, involved in an arms race with other trees to grow taller.

Asymmetrical arms races are a better focus for complexity arguments than symmetrical ones.

Consider a possible arms race pairing up of a rabbit and a fox. Whether this happened between these two species exactly is another question but it will help in understanding the nature of asymmetrical arms races. The fox wants to catch and eat the rabbit for dinner. The rabbit wants to escape the fox and live another day. Bear in mind that arms races take place over lineages not individuals17. The fox lineage is ‘pushed’ towards being faster and faster at running because of the pressure to catch the rabbit for survival. Similarly, there is a strong selection pressure on rabbits to be able to outrun predators such as foxes. Over time this results in dual ‘improvement’ of the animals’ faculties. Such arms races occur between predator and prey, parasite and host, and even between male and female of the same species, as when male peacocks develop huge garish tails and females get higher standards for what is a attractive enough tail18.

The difference between symmetrical and asymmetrical arms races is that asymmetrical arms races allow for multiple realisability. There may be many ways for a rabbit to avoid the fox; with faster running, or better smelling, or quieter movement. The tree, on the other hand, can only grow taller than the other trees if it needs to get sunlight. Of course, being in a symmetrical arms race ought not to preclude being able to change to an asymmetrical arms race at any time, as Dawkins mistakenly seems to be suggesting 19. Just because the arms race the tree is involved in at the moment is symmetrical, this does not rule out the possibility that a certain tree variety might start to increase its chances of getting sunlight in other ways. The fire starting propensities of the Australian Eucalyptus tree is a fine example of this.

15

Dawkins, 1986, p. 169

16

ibid, p. 185

17

Dawkins, 1982, p. 61

18

Dawkins, 1986, p. 178

19

ibid. pp. 185-187

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Dawkins stresses that arms race fuelled changes are net rather than continual progress 20.

Moreover, the actual evolutionary picture is a lot more complicated than a simple example makes it appear. Any lineage can be in multiple arms races at a time, with some having far greater importance than others. Gazelles, for instance, are in a critical arms race with lions to get faster at running, while are in a less crucial (form the point of view of the gazelle) arms race with insect parasites living on their backs. The insects will be evolving towards staying firmly attached to the gazelle as their niche. On the other hand, the gazelle’s body mechanisms will try to cast out these parasites. But failure to outrun the lion and failure to eradicate the pests are far different outcomes, hence the lion arms race is more selectively important for the gazelle.

This leads me to suggest that the concept of arms races alone is not enough to give us an increase in complexity. Arms races appear to go nowhere because of the ‘Red Queen’ effect; the equipment of the lineages may change over time but the success rate rarely changes.

Furthermore, it does not even seem the purpose of arms races to change success rates. If the lion becomes too much faster than the gazelle it will destroy the gazelle population, and hence destroy a great part of its own livelihood. So, it is inherent in the concept of arms races that they have some plateau point. Dawkins acknowledges this also 21. After a certain point in an arms race, one or both of the organisms involved reach a point where further development is inefficient, or the ‘cost’ is too high. Thus, there is a physiological fact about how fast a gazelle can possibly travel using its current anatomy. This is even further limited by considering the energy costs a creature must put into having more extended abilities. I challenge the contention that having faster lions and gazelles demonstrates any increase in complexity.

Surely an equally plausible complexity criteria would be in performing survival duties as efficiently as possible? If this is so, putting more energy into running faster to catch the same amount of prey cannot be classified as complexity growth.

AGAINST COMPLEXITY Setting aside the question of whether purported cases of X increase are cases of complexity increase, we should return again to the debate over whether even net increase has occurred. I earlier stated that net increase was a widely agreed to notion, but this needs serious qualification. Raup asserts that since the Phanerozoic (approximately 600 million years before present) sophistication levels have operated more like a stockmarket, with constant flux, than a net increase22. This is rejected by Dawkins who uses an E.Q. (enchephalication quotient) to determine that brain sizes have increased proportional to body size over time 23. So there are questions over whether complexity taken as body sophistication has increased. Alternately, the relatively unproblematic question of increased biomass and individual numbers is more agreed upon; it has occurred.

20

ibid. p. 181

21

Dawkins, 1986, p. 183

22

Raup, 1993, p. 32

23

Dawkins, 1986, p. 169

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The recurrence of sophisticated developments in evolutionary history should further cast doubt on whether evolution has a complexity enhancing direction. Flight and vision have evolved in different lineages numerous times 24. This is in stark comparison to the common misconception that all organisms take advantage of sophisticated developments that occurred early in the evolutionary picture. Tropical reefs, a sure barometer of species diversity in the sea, have popped in and out of existence six times since the beginning of the Cambrian25.

Consequently, we cannot dogmatically assume that evolution directs itself towards more complex systems.

In one trivial sense, more complexity exists now. Multicellularity and other evolutionary adaptations (such as skeletons and nervous systems) cannot come before the initial life in the primordial soup. Some would see this mere chronological fact as an argument towards increasing complexity but this is erroneous: evolution throws up possibilities through time, simple maths tells us that these new possibilities succeed from time to time. Stringing these successes together and overemphasising their order is how we arrive at a progress theory of complexity. However, given the recurrence of adaptations, we can order them in either direction. It is no more than human pride that makes us do it otherwise.

CONCLUSIONS I began this research convinced that progress must occur in evolution. This is the mistake of many that work in this field26. After examining non-biological progress suggestions like intelligence and plain ‘improvement’ it turned out we would require much more information than we currently have. Simple biological standards could be proven, such as biomass increase and species number difference. However, such discoveries are not equivalent to the ambitious notion people have in mind when postulating evolutionary progress. Finally, basing progress on complexity increase proved to be a challenging task. This is largely due to the difficulty of finding one solid formulation of what complexity is, or, perhaps more importantly, what kind of complexity increase we would count as progressive.

Unfortunately there has not been enough time in this discussion to examine the many further intricacies of the complexity arguments around. Thermodynamic, increasing body size and additional body component arguments could all beneficially affect the case for progressive evolution27. It is suffice to say, in conclusion, that none of the considerations canvassed gave overwhelming support for the thesis.

24

Raup, 1993, pp. 34 & 39

25

Raup, 1993, p. 38

26

Ayala, 1988, p. 83 – such as Kimura and Huxley

27

McShea, 1991, pp. 307-308

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BIBLIOGRAPHY Ayala, F. 1988. “Can ‘Progress’ be defined as a biological concept?” in Nitecki, M. Evolutionary Progress, Chicago, Chicago University Press Dawkins, R. 1982. The Extended Phenotype, Oxford, Oxford University Press 1986. The Blind Watchmaker, New York, Norton Hull, D. 1988. “Progress in Ideas of Progress,” in Nitecki, M. Evolutionary Progress, Chicago, Chicago University Press McShea, D. 1991. “Complexity and Evolution: What Everybody Knows,” Biology and Philosophy, 6, 303-324 Raup, D. 1993. Extinction: Bad Genes or Bad Luck, Oxford, Oxford University Press Nitecki, M. 1988. “Discerning the criteria for concepts of progress,” in Nitecki, M. Evolutionary Progress, Chicago, Chicago University Press Sterelny, K. and Griffiths P.E. 1999. Sex and Death: an Introduction to Philosophy of Biology, Chicago, University of Chicago Press

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