Kevin Laland has just published another critique of modern Evolutionary Theory. This one appears in Aeon [Evolution unleashed]. His criticism is based on a naive and outdated view of modern evolutionary biology. That view has been widely criticized in the past but Laland continues to ignore such criticisms [e.g. Kevin Laland's new view of evolution].
If you are not a biologist, you’d be forgiven for being confused about the state of evolutionary science. Modern evolutionary biology dates back to a synthesis that emerged around the 1940s-60s, which married Charles Darwin’s mechanism of natural selection with Gregor Mendel’s discoveries of how genes are inherited. The traditional, and still dominant, view is that adaptations – from the human brain to the peacock’s tail – are fully and satisfactorily explained by natural selection (and subsequent inheritance). Yet as novel ideas flood in from genomics, epigenetics and developmental biology, most evolutionists agree that their field is in flux. Much of the data implies that evolution is more complex than we once assumed.Count me as one who is confused. I don't believe that modern evolutionary biology is the same as the synthesis from 50 years ago. I think it changed considerably in the late 1960's to incorporate the latest discoveries in population genetics. It expanded to place more emphasis on random genetic drift and Neutral Evolution. Those were significant changes. Modern evolution textbooks are very different from those in the 1960s.
Let's take a look at one of these textbooks. The following quotation is from Evolution (2nd ed.) by Douglas Futuyma (p. 322). This is not the latest edition; it was published in 2009.
In developing the theory of selection so far, we have assumed an efffectively infinite population size. However, in a finite population, allele frequencies are simultaneously affected by both selection and chance. As the movement of an airborne dust particle is affected by both the force of gravity and by random collisions with gas molecules (Brownian movement), so the effective size (Ne) of a population and the strength of selection (s) both affect changes in allele frequencies. The effect of random genetic drift is negligible if selection on a locus is strong relative to the population size—that is, if s is much greater than 1/(4Ne), i.e. if 4Nes>1. Conversely, if s is much less than 1/(4Ne) (that is, if 4Nesnearly neutral. The critical value is 4Nes: genetic drift predominates if selection is weak or the effective population size is small.The blind worship of natural selection is not evolutionary biology. It is arguably not even science.
Thus, even something as fundamental as the idea that adaptations are "fully and satisfactorily" explained by natural selection is not part of modern evolutionary theory. It's been known for many years that both selection and drift play important roles in adaptation [Learning about modern evolutionary theory: the drift-barrier hypothesis].
The statement in Futuyma's textbook was not the way evolutionary biologists thought about evolution in the heyday of the Modern Synthesis back in the 1950s. This change in our way of thinking about evolution may not have been a "paradigm shift" but it was pretty close.
I want to make two points.
- The modern view of evolution is much different that the views of 50 years ago in spite of what Kevin Laland says.
- Most of the proponents an Extended Evolutionary Theory (EES) share Laland's out-of-date views on modern evolutionary theory. They missed the revolution that took place 50 years ago.
Apparently, Kevin Laland and his EES colleagues weren't paying attention during that part of the meeting.
1. The history of life is not the same as evolutionary theory. Evolution is the underlying process that explains the history of life. Our understanding of developmental biology helps us recognize the particular directions that lineages took over the course of millions of years but evolution still requires changes in the frequencies of alleles in a population and that's what evolutionary theory is mostly about [Replaying life's tape].