Nature News has an article on the recent conference in Altenberg, Austria that brought together 16 biologists who want to change evolutionary theory. The article by John Whitfield covers both sides of the story reasonably well [Biological theory: Postmodern evolution?].The bottom line is that many of the participants at the conference are advocating changes to evolutionary theory that are either unnecessary or wrong. This is especially true of the evo-devo crowd as Whitfield makes clear from his interview with opponents of evo-devo.
But lost in all the hype is a real need to address some problems with the Modern Synthesis that didn't even come up at the meeting. The problem is very clear from the article. Here's how John Whitfield describes the current version of the Modern Synthesis.
Leaving aside the troublesome adjective, what is the modernism that the Altenburg meeting is meant to move beyond — or to use Pigliucci's preferred term, 'extend'1? Between about 1920 and 1940, researchers such as the American Sewall Wright and the Englishmen Ronald Fisher and J. B. S. Haldane took Charles Darwin's ideas about natural selection and Gregor Mendel's insights into how traits pass from parents to offspring — which many biologists of the time believed antithetical — and fused them into a mathematical description of the genetic makeup of populations and how it changes. That fusion was the modern synthesis. It treats an organism's form, or phenotype, as a readout of its hereditary information, or genotype. Change is explained as one version of a gene being replaced by another. Natural selection acts by changing the frequency of genes in the next generation according to the fitness of phenotypes in this one. In this world view, the gene is a black box, its relationship to phenotype is a one-way street, and the environment, both cellular and external, is a selective filter imposed on the readout of the genes, rather than something that can influence an organism's form directly.This is a view of evolution that doesn't recognize random genetic drift as an important mechanism of evolution. Surely in 2008, a publication like Nature shouldn't be publishing the old-fashioned adaptationist view of evolution? What's wrong with adding one sentence to say that Sewall Wright also took an idea that Charles Darwin never heard of, random genetic drift, and incorporated that idea into our modern understanding of evolution so that we now recognize that random genetic drift is one of the main mechanisms of evolution?
I think the main reason we don't see such a description is because people like John Whitfield are completely unaware of any mechanism other than natural selection. Or, at least, unaware of the fact that it could be important and needs to be part of modern evolutionary theory.
The Modern Synthesis needs to be updated but updated in the manner described by Stephen Jay Gould and not by the Altenberg 16.
6 comments :
This a pretty 'heavy' topic. There is no doubt that many of the current models of evolution are simplistic; however, that is why they are 'models'. There's something important to be said about incorporating ideas from evo-devo, such as developmental contingency. Furthermore, there's very little work being done in assessing the ontogenic effect of gene expression/action on evolution (e.g., genes expressed in embryogenesis evolve slower than those expressed in adulthood). This being said, I agree with Jerry Coyne in that we need to be careful before claiming that 'evo-devo' provides a brand new 'mechanism' of evolution, as some have suggested, rather than refining our understanding of extant evolutionary dynamics. On these topics, I think Gould would have approved.
With regards to drift, I think that the population genetics crowd have been on the bandwagon for a long time. Gross selectionism seems to pop up a lot in evolution intended for the public. I also see a disturbing amount of it being used by fields that begin at the phenotype and try to work back to some 'paleopoetic' scenario as well...
Yeah, drift was a direct product of the Modern Synthesis, discovered and promoted by population geneticists, and furthermore is mathematically incorporated directly into modern theory, isn't it kind of hard to argue that drift is lacking from the Modern Synthesis and that this is the most important revision that could be made?
Agreed that a some of the Altenberg stuff is hype, I kind of think that modern evolutionary theory is sufficiently pluralistic and diverse that devising some kind of new grand unified scheme equivalent to the population genetics synthesis is probably hopeless.
the most pathetic bit is that some ultradarwinians (which are usually deep into anticreationism and "rationalism") are using creationism as an excuse to put the boot down on any criticisms pointing out the insufficiency of natural selection as the "main topic" for understanding of evolution. Jerry Coyne mixes his anticreationist talks with one-sided criticism to anythign that is not orthodox neodarwinism, like in the 50's.
For these cycnical, uppity granpas, no theoretical framework better than natural selection will ever be possible.
oplopanaz asks,
Yeah, drift was a direct product of the Modern Synthesis, discovered and promoted by population geneticists, and furthermore is mathematically incorporated directly into modern theory, isn't it kind of hard to argue that drift is lacking from the Modern Synthesis and that this is the most important revision that could be made?
Random genetic drift was pretty much purged from the hardened version of the Modern Synthesis that evolved at the time of the Darwin centennial in 1959.
Now it needs to be added back.
I find autopoiesis, the logic of the organism, to be more important than population approaches for an adequate understanding (no leaps or balck boxes) of both biology in general and evolution in particular. So there!! haha
Just stumbled by because I was trying to find out more about this 'secret meeting'. Interestingly, I agree with parts of just about everything said here, so I'd thought I'd add my two cents.
The ENCODE project left many of us (working in the human genome sciences) thoroughly confused. If you read the ENCODE paper (Nature 2007), one the most surprising findings (in my opinion) is that functionally critical elements of the genome are not necessarily under selection pressure. They also found regions of the genome with no evidence of function that are also under selective pressure. The latter may be explained by simply not looking at the 'right' cell type or developmental period, etc. The former however, necessitates that we broaden the evolutionary view a bit ("a more neutral view" - as reported by the ENCODE researchers). Kimuru and Gould would be pleased...
I get frustrated because you can't even begin this discussion without accusations of believing in the tooth fairy or the flying spaghetti monster. There are some in this discipline who refuse to update or refine a theory based on new evidence (i.e. the scientific method) for fear of this bizarre sect of society known as creationists. In an age when the Vatican is studying evolution, I think we can do better. Just my two cents. Thanks for the blog and comments.
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