Extending Evolution in London?

I was dispatched to London earlier this month for the Royal Society’s big conference on evolutionary science (the Royal Society is roughly equivalent to our National Academy of Sciences). The conference title was “New trends in evolutionary biology: biological, philosophical and social science perspectives” (see conference webpage here). The goal was to explore what proponents are calling the Extended Evolutionary Synthesis (EES), which seeks to replace the Modern Synthesis (sometimes called neo-Darwinism).

Essentially the EES folks charge that the Modern Synthesis is committed to explaining all of evolution by random genetic mutations and natural selection, and it hasn’t kept up with the surprising developments in evolutionary science in the last 50 years that should cause us to rethink the theory. These developments are things like niche construction, evo-devo, inheritance of acquired characteristics, and phenotypic plasticity. Modern Synthesis supporters respond to these charges with, “Yes, these are interesting special cases and add some nuance, but hardly constitute overthrowing the general paradigm of the Modern Synthesis.”

This was the same conversation in the 2014 paper in Nature, “Does Evolutionary Theory Need a Rethink?” in which proponents of both sides made their case. Our blog author, Michael Burdett, gave a nice summary of the paper in his post, The Changing Face of Evolutionary Theory? It is worth a read to familiarize yourself with more of the details of the arguments.

I learned a lot of cool science at the meeting, but did not come away feeling that any progress had been made in either overthrowing the dominant paradigm or establishing a new one. There were very few empirical details that were in question, so it was mostly a matter of how these facts are organized and conceptualized. Those kinds of disagreements are rarely settled by offering more empirical evidence. The opposing positions are ways of looking at things, paradigms, or even worldviews.

Knowing some history and philosophy of science, I couldn’t help wondering how this dispute compares to others in the history of science. To hear the rhetoric from some corners, you’d think it is nothing short of a scientific revolution along the lines of Newton’s overthrowing of Aristotle. Newton replaced Aristotle’s understanding of physics wholesale, and he united the celestial and terrestrial movements into one elegant system. Nothing of the sort is going on with EES.

Neither is this the same sort of revolution as Einstein’s revision of Newton. Newton’s laws still work just fine if you’re building a backyard patio or throwing a baseball. What Einstein did was to show that these are just approximations, though, and the faster you’re going or the more massive the objects you’re working with, the less accurate the Newtonian approximations will be.

The EES is not claiming that the genetic basis of evolution is just wrong (like Newton said of Aristotle), nor that it is only approximately correct in certain situations (like Einstein said of Newton). The genetic code really does mutate, causing differences at the phenotypic level, and these are passed on to offspring. What the EES does is show that there are complicating factors. For example, when an organism alters its environment (that is, constructs a niche), it affects the kinds of organisms that will be most successful in that environment. Think of a beaver constructing a dam and altering the ecosystem, or humans developing agriculture and settling down from their hunter-gatherer mode of existence.

So how important are these complicating factors? “They are pretty interesting and should be further researched,” say the defenders of the Modern Synthesis. “They are massively important and should cause us to reenvision evolutionary theory,” say the EES proponents. “Scientists Seek to Update Evolution” is a very good article at Quanta Magazine summarizing the conference by NY Times science writer Carl Zimmer.

What is very important to take away from all of this is that evolutionary science is not in crisis, as some would have you believe. The big picture of the theory, according to which all life shares common ancestors, is massively supported and not questioned in any way by either side of disagreement. Instead, they are arguing about details of mechanism and relative importance of special cases. That’s what science does. See our Common Question, “Is Evolution a Theory in Crisis?” for more.