The “Modern Synthesis” is what we now call the form of Darwinism that emerged in the aftermath of the “Crisis of Darwinism.” That crisis was precipitated by Thomas Hunt Morgan, of fruit fly genetics fame, that essentially drove a stake through the heart of Darwinism. His theory of evolution, called mutationism, asserted that evolution could only proceed through gene mutations. Natural selection and adaptation could play no role in Morgan’s gene-centered world.
The Modern Synthesis is supposed to have rescued Darwinism from Morgan’s mutationism. Its originators (Ronald Fisher, Sewall Wright and J B S Haldane) showed how natural selection could work in Morgan’s gene-centered world, but they did so in a way that left mutationism intact at its heart. The Modern Synthesis is often called Neodarwinism, but it’s hard to defend that term, because gene mutationism still sits at the heart of it.
What’s missing, as I argue in Purpose and Desire, is a coherent theory of adaptation: the tendency of living systems toward “apt” form. Adaptation has long been a problematic concept for Darwinism. It is the essential link between the living organism and natural selection. Yet, adaptation is a fundamentally a phenomenon of cognition and intentionality, a no-no in the mechanistic presumptions of modern Darwinism. Much of the history of evolutionary thought has been spent in trying to wriggle out of that inconvenient conundrum. I lay it all out in Purpose and Desire if you want to learn more.
Right now, the hot topic is the so-called Extended Evolutionary Synthesis (EES) which is supposed to account for this problem. The motivation is sound: the Modern Synthesis is a genetic theory of evolution, where actual evolution is a story about the evolution of form (dogs look different from wolves, Equus looks different from Eohippus, etc.). This is where adaptation should be coming in, but doesn’t. Look at these two Venn diagrams (from a forthcoming paper by Emanuele Serrelli) showing two different representations of the EES (from the same author, incidentally). The MS is the center set and the EES is everything surrounding it.
- The EES certainly encompasses a lot of things it should, things like epigenetics, niche construction, natural history. So, A for effort. But what’s the relationship between all of them? It’s a bit of a grab-bag.
- What’s missing from all this is ADAPTATION! Why? Because it’s inconveniently purposeful!
Serrelli E (2017). Metascientific views: Challenge and opportunity for philosophy of biology in practice. Acta Philosophica 26(1): 65-82.
Purpose and Desire is available from 12 September 2017. It is available at a substantial discount for pre-order now. See purposeanddesirebook.com for more detail