Saturday, June 28, 2008
Darwinism at the ROM
Yesterday I attended a symposium on evolution at the Royal Ontario Museum [Darwin Symposium at the ROM]. The emphasis was on Charles Darwin, in line with the Darwin exhibit that is currently running at the ROM.
What I was expecting was a series of lectures that explain how Darwin fits into modern ideas of evolutionary biology. What I got was an adaptationist lovefest.
This was a free public symposium. By the time it started every seat in the auditorium was full and people were standing at the back. There were about 320 people of all ages and all walks of life. I sat beside a high school teacher and talked to retirees from the suburbs.
The first speaker was Michael Ruse. The original title of his talk was Has Darwinism Expired? but he modified it slightly to Is Darwin's Theory Past Its "Sell By" Date. His opening remarks were promising because he mentioned Stephen Jay Gould and Gould's criticism of Darwinism. He said that this was a distorted picture of evolution. It was downhill from that point on.
Ruse never explained why modern evolutionary theory differs from Darwin's evolution by natural selection. Instead he spent close to an hour going over examples of "evolution by natural selection." Most of his examples were, indeed, evidence of evolution but they were not necessarily evidence of evolution by natural selection. It's clear that Micheal Ruse does not distinguish between "evolution" and "natural selection." Evidence for evolution is treated as evidence for natural selection.
By the time he finished, the audience was completely unaware of random genetic drift, or any other mechanism of evolution. Ruse never explained why anyone would even bother to ask the question he asks in the title of his talk. According to Ruse, Darwinism is still the dominant paradigm in evolutionary biology. When examining characteristics of organisms biologists always ask "What is it for?", according to Michale Ruse. The answer will be explained by natural selection. This is the adaptationist fallacy. The correct question should be "Is this "for" anything?"
I know that Ruse is more of an adaptationist than a pluralist. I know that he favors Richard Dawkins and Daniel Dennett over Stephen Jay Gould and the pluralists. That's not the problem. What bothers me most is that when giving a public lecture Ruse does not even present the other side of the issue. What would it have cost him to mention that there are many evolutionary biologists who do not think of themselves as Darwinists? Why couldn't he explain that many of us think random genetic drift—and not natural selection—is the dominant mechanism of evolution? It doesn't diminish the importance of natural selection and adaptation. It doesn't diminish the contribution of Charles Darwin who still remains the greatest scientist who ever lived.
The second talk was by Spencer Barrett of the Department of Ecology & Evolutionary Biology here at the university of Toronto. Spencer Barrett was recently appointed to the rank of University Professor, our highest rank, in recognition of his work on evolution in flowering plants.
The title of his talk was A Darwinian Perspective on the Evolution of Plant Sexual Diversity and that's an accurate reflection of its content. Spencer Barrett is an adaptationist but in terms of his research he's a very successful example of this wordview. He chooses examples from plant evolution that almost certainly are adaptive and can be explained by natural selection. When faced with a strange example of plant sexual organs, Barrett begins by asking "What is the adaptive significance?"
After lunch we were treated to a lecture by Peter and Rosemary Grant on the evolution of Darwin's Finches. Most of you know the story. The Grants have spent 30 years collecting data on finches in the Galapagos. Everything about the evolution of Darwin's finches is explained by natural selection, especially changes in beak size. It has become the dominant example of evolution by natural selection.
The last lecture was delivered by Allan Baker of the Royal Ontario Museum. his title was Modern Darwinism: Natural Selection and Molecular Evolution. Baker works on bird evolution at the molecular level. He is trying to sort out the complicated, and controversial, relationship of bird clades. Baker pointed out that there are many conflicting data sets in the field and he explained how the use of signature sequences—in his case retrotransposon insertions—can be helpful. He noted in passing that he disagrees with the recent Science paper and cautions that bird evolution is still very much up in the air.
The irony here is that Baker was not studying "Darwinian" evolution at all. In spite of his title, it's extremely unlikely that the changes he looks at are due to natural selection. This was another missed opportunity, in my opinion. Baker could have explained to this public audience that molecular evolution is not Darwinian. It is an example of random genetic drift, which, incidentally, is why there's a molecular clock.
In talking to the lecturers afterward, I tried to find out how they thought about evolution. Baker, is well aware of the importance of random genetic drift. Barrett does not agree with me when I say that random genetic drift is the dominant mechanism of evolution at the molecular level and he does not agree that drift plays a role in speciation. Professor Barrett is one of the lecturers in our first year biology course on ecology and evolution. I've pointed out previously that in my second year course the students do not understand or appreciate random genetic drift and they tell me that it is barely mentioned in first year [Freedom in the Classroom]. I really enjoyed talking to Spencer Barrett and I hope we can continue the debate at another time.
The Grants claim that their evidence for natural selection is strong enough to rule out random genetic drift during the years when most of the finch population dies of starvation. The fluctuations in between could be due to drift.
Further reading ...
What Is Darwinism?
A Confused Philosopher
Darwin and Design by Michael Ruse
Why I'm Not a Darwinist
Evolution by Accident
Random Genetic Drift
Visible Mutations and Evolution by Natural Selection
Dennett on Adaptationism
The Evolution Poll of Sandwalk Readers