Are we ready for an “extended evolutionary synthesis”?

Over at Time magazine, Carl Zimmer has a good essay, “The Ever Evolving Theories of Darwin”, about Darwin’s contributions and what has happened in evolutionary biology since 1859. The essay was kind of spoiled for me, though, by the ending, in which Zimmer seems to buy into something he calls the “extended evolutionary synthesis”. To quote Zimmer:

In the mid-1900s, biologists succeeded in merging the newest biological developments at the time into a new vision of evolution known as the Modern Synthesis. Today a number of biologists argue that it’s time for a new understanding of evolution, one that Pigliucci has called the Extended Evolutionary Synthesis. For now, they are fiercely debating every aspect of that synthesis–how important gene-swapping is to the course of evolution, for instance, and how gene networks get rewired to produce new traits.

Some researchers argue that many patterns of nature–such as the large number of species in the tropics–cannot be reduced to the effect of natural selection on individuals. They may be following rules of their own. “Which of these ideas is going to actually survive and prove fruitful is anybody’s guess,” says Pigliucci. “I don’t see things coalescing for at least a decade or more.”

It seems to me that a science journalist should do more than simply tell their readers that something new is in the air: a journalist should EVALUATE these new claims. If all one did was say “some evolutionists think. . .”, and then describe their thoughts, any old claim could get press.

It just isn’t true to say that every aspect of the Modern Synthesis is fiercely debated. Richard Goldschmidt, the most distinguished contemporary opponent of the Modern Synthesis, was wrong about speciation, about mutation, about genetics, about the origin of higher taxa, among other things; the Synthesis got all of these pretty much right. Much of WEIT summarizes general conclusions originating in the Modern Synthesis (and the abundant evidence that supports them), about which consensus in evolutionary biology is both broad and deep (WEIT is the 250-page version; for a two-page version of the conclusions, see pp. 10 and 11 of Doug Futuyma’s Evolution, Sinauer, 2005).

And who ever said that the pattern of greater species diversity in the tropics could be completely explained by natural selection? There is the little matter of differences in climate, habitat, and geological history. We already know pretty much that gene-swapping is unlikely to be important in the evolution of many species, like vertebrates (it may play some role, but surely not a major one!), and nobody has suggested that gene networks get rewired by any means other than natural selection.

We have surely gone way beyond Darwin in our understanding of the pattern and process of evolution. But I am irritated by the constant appearance of what I call “BIS”–the Big Idea Syndrome. An evolutionist finds a new phenomenon, say transposable elements, or epigenetics, or “modularity,” and suddenly that one phenomenon becomes the centerpiece of a claim that modern evolutionary theory is ripe for a revolution. Yet when you look for the beef, it isn’t there. Where are all the examples of genetic assimilation, a phenomenon that was said to completely overturn our views?

I may sound curmudgeonly here, but it behooves all of us—especially journalists—to think twice before proclaiming that evolutionary biology is about to experience the equivalent of quantum mechanics.

Note added:  Over at his blog, Rationally Speaking, Massimo Pigliucci has taken issue with my characterization of the “extended synthesis” debate, and I recommend that people read his  case for this synthesis.  I don’t want to get into squabbling, but want to make one point. Massimo says the following:

Jerry is “irritated” by what he calls “BIS–the Big Idea Syndrome,” where any new idea that comes about, be it modularity, evolvability, evolutionary capacitors, epigenetic inheritance, phenotypic plasticity, genetic accommodation, species selection, cis-regulatory evolution, and so on and so forth, “becomes the centerpiece of a claim that modern evolutionary theory is ripe for a revolution.” Again, nobody I know is calling for a revolution, but the above mentioned ideas and empirical evidence cannot simply be filed away as “more of the same.”

Well, I beg to differ, and I think anyone who has read the literature on evo devo, genetic assimilation, modularity, and the like will realize that some of their proponents (I don’t want to name names here) are self-consciously claiming that neoDarwinism is incomplete in very important ways, and that some new viewpoints (not just new data or phenomena) are needed.  Let’s look at part of the invitation to the Altenberg 16 conference:

As you know because you have been involved in this to some extent, for some time now there have been persistent rumors that the Modern Synthesis (MS) in evolutionary biology is incomplete, and may be about to be completed. Such suggestions have been received with skepticism by a number of biologists, including some of the very originators of the MS.

The challenge seems clear to us: how do we make sense, conceptually, of the astounding advances in biology since the 1940s, when the MS was taking shape? Not only we have witnessed the molecular revolution, from the discovery of the structure of DNA to the genomic era, we are also grappling with the increasing feeling – for example as reflected by an almost comical proliferation of “-omics,” that we just don’t have the theoretical and analytical tools necessary to make sense of the bewildering diversity and complexity of living organisms.

This implies, at least to me, that we cannot grasp “the bewildering diversity and complexity of living organisms” without some new tools and insights.  I am not yet willing to sign onto this, because I think the theoretical tools–the idea of natural selection and mathematical population genetics–are already at hand, and although we may get new analytical tools (such as genomics!), the rest is just hard grinding work trying to understand speciation and natural selection in the wild.  I may be wrong, but I don’t scent revolution in the wind yet.

I close with a statement by my old mentor, Dick Lewontin, who of course as an old Marxist would be in favor of revolutions:

“The so-called evolutionary synthesis – these are all very vague terms. . . . That’s what I tried to say about Steve Gould is that scientists are always looking to find some theory or idea that they can push as something that nobody else ever thought of because that’s the way they get their prestige. . . .they have an idea which will overturn our whole view of evolution because otherwise they’re just workers in the factory, so to speak. And the factory was designed by Charles Darwin.”