Friday, March 11, 2005

On the fringe.

I've recently been introduced to another "anti-darwinist" on the Panda's Thumb, John A. Davison professor of zoology at the University of Vermont. Dr. Davison has an evolutionary manifesto published on his website, in which he claims that natural selection on allelic variation does not result in major evolutionary changes. He also likes to poke fun at mainstream evolutionary biologist by calling us "Darwimps."

In all honesty, I have not read Davison's entire manifesto nor his article on the Prescribed Evolution Hypothesis (PEH). He did not tell me what PEH stands for and where I could find the article, so it took a bit of searching on my part to locate it. I hope to have a post discussing his ideas in more detail in the coming weeks. For now, I'd like to focus on Dr. Davison's misunderstanding of how most biologists understand evolution based on my interactions with him and the parts of his manifesto that I have read.
Perhaps the most compelling feature for the Darwinists resides in their persistent conviction that all of evolution is the result of blind chance. In so doing, the Darwinists refuse to consider that evolution might be subject to laws and precise mathematical relationships such as those that govern virtually every aspect of the inanimate world. (from Davison's manifesto)
Apparently Davison does not realize that Darwinian evolution is a deterministic process (as opposed to stochastic). By definition, deterministic processes do NOT work by chance. The raw material on which natural selection operates (mutations of different sorts) is generated via mutation (a stochastic process). This is a point we should be hammering home as often as possible. Yes, there are stochastic processes involved in the the most widely held scientific view of evolution (mutation, genetic drift, environmental changes), but natural selection is not random. If he does not understand this simple concept (covered in any undergraduate evolution course) how can I take anything in the manifesto seriously.

Davison likes to focus on karyotypic evolution and he believes that genome rearrangements are the things that can cause evolution. I don't dispute his claim that genome rearrangements are important in evolution, but they are just another stochastic event that influence recombination rate (yet another, stochastic process). Recombination rate influences the strength of natural selection (search "recombination" and "selection" in PubMed to see the laundry list of publications), and we're back to the deterministic nature of evolution.

Davison seems to focus on one topic (genome rearrangements) while ignoring all of the other evolutionary forces. Each force is not an isolated mechanism, but rather part of a larger system in which the interaction of natural selection, population size and structure, genetic recombination, environmental changes, learned behaviors, etc. cause evolution. There is a random nature to evolution, but there are also rules that govern how the random events occur (probability distributions) and deterministic processes (natural selection) that depend on those random events.


At 2:00 AM, Blogger Paul said...

I have a friend over there at UVM, and he hasn't ever mentioned this guy (he's in Chemistry though, and new). And to think this Davison cat got his Ph.D. from my alma mater, it makes me sad. It seems (from a brief perusal of his old page) that he is really trying to claim that his idea of how variation occurs is somehow missing from the neo-Darwinian synthesis. I don't really see it, myself. It reminds me of the Margulis/Sagan book (Acquiring Genomes?, I can't remember the title), that was basically about her wonderful idea of symbiogenesis. Where it goes awry is the claim (made by others, typically, in that case) that this somehow invalidates Evolution (cap. E) when it really just adds a novel mechanism, as anyone trained in molecular or general genetics would immediately understand. Which is why these things usually come from classically trained zoologists/biologists of the "old school", I guess.

At 9:45 AM, Blogger RPM said...

Davison agrees that evolution has happened and he acknowledges the age of the earth. He disputes the idea the natural selection can lead to significant evolutionary change (he views it as an anti-evolutionary force in that it selects against novel forms). He believes that major evolutionary changes and speciation occur spontaneously via chromosomal rearrangements. Once I've taken a detailed look at his "evidence" I plan to post a more comprehensive rebuttal

At 9:45 AM, Blogger RPM said...

He also believes that evolution no longer occurs on earth.


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