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
Adaptationomics
Dennett on Adaptationism
The Evolution Poll of Sandwalk Readers
In BIO150, Spencer Barrett's adaptationism was mild compared to the 2nd quarter of the course, taught by Locke Rowe when I took it. We learned about foraging behaviour, mating behaviour, predator-prey arms races, male-female arms races, selfish genes, evolutionary medicine, etc...all viewed through the lens of an axiom that said "natural selection has worked to maximize organisms' fitness."
ReplyDeleteI find the comment on the curriculum most interesting.
ReplyDeleteOver here in the UK in one of my first year courses entitled "ecology and evolution" we had three lectures on the evolution aspect that gave as much time to genetic drift as they did to natural selection.
Funnily enough it was the discussion of genetic drift that reeled me in and from that day onwards I knew evolutionary biology was what I wanted to do. I find it absolutely perverse that such a massive element of evolution is so widely ignored- I'm very grateful to that Professor who realised just how vital it was for us as biology students to understand drift. When I do my teaching next year I'm going to make sure every single one of my students knows exactly what it is.
postdiluvian
ReplyDeletewhat was the title of the course or the focus of the second half? Sounds like behavioral ecology to me, which by its own definition as a field of study examines how natural selection works to maximize organisms fitness.
The course is an introductory first-year course called "Organisms in their environment." Description: "Principles and concepts of evolution and ecology examined through examples at the level of individuals, populations, communities and ecosystems. Includes the application of ecological and evolutionary approaches to behaviour, genomics, evolutionary medicine, global environmental change, and conservation biology."
ReplyDeleteIt is a required course for all life science students and I gather is meant to set the groundwork for further studies in the life sciences.
I'd agree that the evolution aspect of the course isn't very well covered. Much of the course is an introduction to ecology, like nitrogen cycles, habitat carrying capacities, and so forth.
ReplyDelete