From: rhinoceros (rhinoceros@freemail.gr)
Date: Mon Apr 19 2004 - 13:45:00 MDT
I am pasting this from a not quite recent book review of "The Riddled Chain: Chance, Coincidence, and Chaos in Human Evolution" by Jeffrey K. McKee, Rutgers University Press, 2000. Does anyone care to take a shot?
http://www.skeptic.com/review12.html
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What the future holds for the evolution wars may be glimpsed in the next generation's writings, an intriguing representative sample of which can be found in paleoanthropologist Jeffrey McKee's The Riddled Chain. The subtitle alone, "Chance, Coincidence, and Chaos in Human Evolution," tells us that this is not a strickly gene-focused, adaptationist analysis. The alliterative reference is to influences outside the traditional forces of study that have shaped the course of evolution; and once again the topic is our favorite species. McKee cleverly draws the reader into theoretical debates about human evolution through personal stories of his own field work in South Africa. But McKee is not just in the search of our origins, which is now reasonably well fleshed out in a very bushy tree of life. There is no linear chain in the "ascent of man" that can be cleanly drawn from Lucy to us. Instead, as McKee demonstrates through a convergence of evidence ranging from fossils to computer simulations, "Natural selection
is severely limited both in its power to promote useful genes and in its freedom to tinker with morphology. Human bodies are not particularly well adapted in many respects, revealing the chance origins of nature's 'designs.' Chance and chaos, as much as the ever vigilant selective process, made us what we are."
To a strict adaptationists like Richard Dawkins and Edward Wilson, these are fight'n words. If natural selection is not the be all and end all of evolution, then what is? Autocatalysis, McKee argues in the book's most daring chapter. "Autocatalytic evolution simply means this: evolution is caused (catalyzed) by itself (auto). It is self-propelled by feedback loops. If this means that most evolutionary change is catalyzed or caused by the inherent nature of a species, then the grand theories of environmental forcing fall away. Evolution would proceed with or without changes in climate or in the plant and animal community with which a species interacts. Evolution is the cause of evolution, and it continues by its chaotic devices." Indeed, autocatalysis is what chaos and complexity scientists call feedback loops, as when a PA system generates "feedback" between the microphone and speakers.
The figure from McKee shows just how nonlinear and interactive the process of evolution can be. The old linear model of bipedalism --> tool use --> meat eating --> big brains --> language --> culture is replaced by an autocatalytic feedback loop in which "each morphological aspect has functional or behavioral consequences or correlates (solid arrows), which in turn reinforce the evolved features through positive natural selection (open arrows)."
Autocatalysis is a superior model for explaining the complexities of life because as biologists have discovered in recent decades (particularly with the rise of the science of ecology), simple linear models fail to account for complex biological systems. The same has to be true for the history of life.
It certainly is in human cultural history, which is riddled with autocatalytic feedback loops and, in fact, forms the core of Jared Diamond's revolutionary work Guns, Germs, and Steel. McKee believes that he's on to something here that could very well start yet another evolution war. "The theory of autocatalytic evolution is painfully simple, horribly mundane, and probably correct."
Is it? The evidence is good, but it is too soon to tell, so as in the debate over Wilson's sociobiology and Mendel's genetics, the battle for science will be determined in both the private and public spheres of influence.
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