The shift to mutationism is documented in our language

Last year Sahotra Sarkar published a paper that got me thinking.  His piece entitled “The Genomic Challenge to Adaptationism” focused on the writings of Lynch & Koonin, arguing that molecular studies continue to present a major challenge to the received view of evolution, by suggesting that “non-adaptive processes dominate genome architecture evolution”.

The idea that molecular studies are bringing about a gradual but profound shift in how we understand evolution is something I’ve considered for a long time.  It reminds me of the urban myth about boiling a frog, to the effect that the frog will not notice the change if you bring it on slowly enough.  Molecular results on evolution have been emerging slowly and steadily since the late 1950s.  Initially these results were shunted into a separate stream of “molecular evolution” (with its own journals and conferences), but over time, they have been merged into the mainstream, leading to the impression that molecular results can’t possibly have any revolutionary implications.

Frog on a saucepan. Image from wikipedia (http://en.wikipedia.org/wiki/Boiling_frog)

Frog on a saucepan (credit: James Lee; source: http://en.wikipedia.org/wiki/Boiling_frog)

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Theory vs. Theory

What does it mean to invoke “evolutionary theory”? Is “neo-Darwinism” (or “Darwinism”) a theory, a school of thought, or something else? What gives a theory structure and meaning?  Can a theory change and, if so, how much?  What is the relationship between mathematical formalisms and other statements of “theory”? Who decides how a theory is defined, or redefined (e.g., is Ohta’s “nearly neutral” theory an alternative to, or a variant of, Kimura’s Neutral Theory of Molecular Evolution)?

For various purposes, it is useful to have a framework for discussing “theory” and “theories”.  Here I begin by identifying two distinct ways that scientists use the word “theory”. 2
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