frontline 10
Gould vs Dawkins: The Great Darwinist Polemic
(One Marxist's View - Part 2)
Stevie Arnott continues his examination of the debate between- scientists Richard Dawkins and Stephen Jay Gould over the question of evolution.
Have you heard the one about the horse..?
Richard Dawkins and his supporters' views can be seen as classically neo-Darwinist gradualism. The theory developed by Gould and his co-worker Nils Eldredge, that the story of life is much more than just gradual cumulative change, but involves crises, mass extinctions, the disappearance of whole species and phyla, and the rapid evolution of survivor species into new niches during the time of these great ecological crises, is known as the Theory of Punctuated Equilibrium.
Australian philosopher Kim Sterelny in his excellent handbook on the Gould/Dawkins controversy Survival of the Fittest, uses the example of the humble horse to illustrate the core difference of viewpoint.
Making the point that both the fossil record and most evolutionary text books "show" a diversity of much smaller horses "evolving" into the much bigger beasts we know today, he then points out
"…the history of horses was one of the paradigms of evolutionary change. In response to the opportunity provided by the evolution of grass, and the establishment of grasslands, horses became prairie animals rather than forest animals. So at least the standard story has it.
But Gould thinks this trend in horse evolution is a mirage. There has not been a directional trend in horse evolution. Rather there has been a massive extinction in that lineage and the paltry surviving remnant happen to be grazers. The appearance of a trend is generated by a reduction in the heterogeneity of that lineage."
The Dawkins view of change has a definite arrow of progress
Ancestor species‡---incremental cumulative selection‡---Z horse species X millennia ago‡----incremental cumulative selection+new grassland environment-‡----Y modern horses.
In the Gould view the appearance of linear progress is a subjective illusion generated by extinctions we cannot see.
<Mass extinction>-‡---ancestor survivor species A rapidly evolves myriad daughter species (B+C+D….Z)---<-‡---period of relative evolutionary stability where cumulative changes wobble about an evolutionary mean----<‡---<New Crises and extinction of majority of daughter species>----‡------modern day horse species = (B+C+D) - (E through to Z).
Note that in the second algorithm "rapidly" means relatively rapidly over geological time scales (Gould does not posit, as some of his detractors have tried to claim, the almost instantaneous explosion of new species). The backward arrows represent the Gould view that change is in time, but that the linear progressive appearance is a product purely of our subjective judgement "looking back", and contingency.
In the first instance there is an evolutionary event horizon beyond which we cannot see, or see only partially. The fossil record and morphological similarity between latter day horses and their ancestors may show evolution from one to the other, but equally they may well have been one time contemporaries, with one set of species becoming extinct, generating the illusion of development. Fossils and bones are but snapshots, and snapshots in time, as any dialectician knows, belong to the category of being, not of becoming. Such evidence can hint at development but rarely show it. Intelligent consciousness must fill in the gaps and intelligent consciousness can deceive itself.
Secondly, things could have been different so easily. Ice ages, solar flares, disease, asteroid collisions - all have been posited as potential causes of the five mass extinctions that have occurred since life on earth began. Gould indeed, was one of the first champions of the idea that a large asteroid collision wiped out the dinosaurs - an idea that is no longer particularly controversial. All of these events break up the evolutionary game and create wholly new dynamics. In the language of complexity theory not only are the attractors of evolution jolted off course, the very design space in which they move is changed. What will emerge from these events, if life survives at all, are wholly new phenomena. Yet these crises need not have happened, or could have happened otherwise.
All of this would have a deep impact on our understanding of horses, but an even deeper impact on our understanding of the tamer of horses, homo sapiens.
Again, there is a schoolbook view of Darwinism informed and culturally coloured by the Victorian paradigm of forward progress from which it emerged. In this view, the slow natural selection of the ages almost inevitably produces as its pinnacle rational, tool using man.
Gould has almost certainly finished off this egocentric view, and not even the stoutest of Dawkinists would now defend it. What they will argue is that life, given enough time, and the correct environmental challenges, will produce intelligence, rationality, self-awareness and tool using. It just wouldn't necessarily produce us.
And like the horses there may have been many proto-hominids that simply did not survive or were wiped out by other hominid competitors. Neanderthal man was essentially a different species of hominid that either died out, or was killed off by our ancestors. The harsh fact of increasing number of proto-hominid remain and fossil discoveries seem to indicate that there were many candidate species from the primate pool ready to make the leap to bipedalism, language and tool-using - but only one did. Beyond the event horizon of our own evolutionary history there may lie the colossal remains of a hundred different would-be histories of intelligent life on Earth.
Thesis, antithesis and …hair-splitting
But surely it could be argued here that the differences between Gould and Dawkins are not as great as they seem?
Despite the many complexities, qualifications, special cases, subtleties and caveats that we do not have the space to deal with here, some biologists and philosophers of science are attempting to sculpt out a synthesis from this great clash of ideas - one that adopts the best features of both views of evolution as backed by the empirical evidence. And on many issues the gulf between the two men is not as great as it once seemed to be.
For instance, essential to Gould's notion that evolution and rates of speciation can be speeded up during and after times of ecological crisis, is the idea that species themselves can be agents of selection - or more correctly can have qualities that are selected for, especially in times of environmental change. Both chance characteristics of a species and/or its broader "adaptability" could ensure that it survives while others do not. Some of those characteristics may then be passed on to daughter species.
As Sterelny summarises once again
"Species survival is not random, but the properties on which survival depends are not adaptations to the danger mass extinction threatens. If a meteor impact causes a nuclear winter, then the ability to lie dormant would have improved your chances. But dormancy is not an adaptation to the danger of meteor impacts.
…But many important characteristics relevant to survival or extinction would have been properties of species themselves. Species with broad geographic ranges, species with broad habitat tolerances, species whose lifecycle does not tie them too closely to a particular type of community all would have a better chance of making it."
Fishes that find themselves without seas or polar bears that suddenly found themselves in deserts would not make it; others might, some even may be coincidentally adapted to the new prevailing environment. Many will survive just - but find that the new environment gives natural selection a kick in a wholly new direction.
Dawkins is not completely opposed to this idea because it does not, in the end challenge a gene based model of natural selection. If organisms are vehicles for the replication of genes, then why can't whole species be too? Dawkins has also reached similar conclusions to Gould approaching from a different angle - and that is that "evolvability" may itself be evolvable.
But beyond and deeper than that neither vision of evolution is mutually exclusive. Indeed, it may well be that ultimately they are both mutually interdependent. Gould does not deny the importance of gradual cumulative selection. This process is the same both in times of crisis and in times of stasis. The "speeding up" of speciation occurs during and after crisis because the environment is changed. It slows down and, perhaps, meanders around a mean point in times when the environment is stable.
For Dawkins, gradualism musts also fit the empirical facts, and the empirical facts on extinctions, speciation and periods of relative stasis are mounting.
Finally, if species themselves are agents of selection and evolvability is itself evolvable", then surely those small changes that do occur during periods of relative stasis may not in themselves be unimportant, for like the "molecular, invisible processes in consciousness" Trotsky described in the masses in the quiescent times before revolution, those small changes set the initial conditions for how those agents will fare in the coming storm. To use a political analogy, the current international task of Marxism in a non-revolutionary period is to build broad socialist parties with a Marxist core. The test of those parties in a revolutionary period will be both whether they are sufficiently theoretically steeled and prepared for the tasks ahead and, crucially, whether they are, or are evolvable into, truly mass parties of the working class with the requisite social weight to carry out a historic overturn. The achievement of these initial conditions is critical. Political extinction may beckon if we fail.
However, we run ahead of ourselves. A new and complete model of species change in the sphere of the biological sciences may yet emerge. A few have already started to refer to the new paradigm as "Punctuated Gradualism".
And such a view will of necessity be wholly coherent with new scientific and mathematical models of universal rules of motion and change. That is to say, complexity and emergent phenomena theory, which will be dealt with in a future edition of Frontline.
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