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Are genes the prime movers in evolution, or is causality distributed across multiple levels of organization?  What role do organisms play in evolution?  Could organismal agency, the propensity to respond actively to selective forces, affect standard evolutionary theory?

On this episode, we talk with Denis Walsh, a professor and philosopher of biology at the University of Toronto, about his book Organisms, Agency, and Evolution. The Modern Synthesis, which combines Darwin’s theory of natural selection and Mendel’s theory of genetic inheritance, was a giant leap forward in our understanding of the evolution of populations. Denis argues, however, that the extreme abstraction required by the synthesis derails our understanding of evolution. What’s needed instead, he suggests, is renewed focus on organisms. Because organisms have agency, they in effect construct the environments they experience, which in turn affects how selection acts on them. This view reestablishes organisms – not genes – as the central unit of evolution, just as Darwin’s ‘struggle for existence’ emphasized.

Photo credit: Blue Dragon nudibranch (Pteraeolidia ianthina) by Saspotato (CC BY-NC-SA 2.0)