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.”

12 Comments

  1. Emily
    Posted February 17, 2009 at 7:44 am | Permalink

    What do Pigilucci & Co. envision as the new synthesis? Why don’t they just go ahead propose their extended synthesis and allow others to evaluate it? I’m tired of hearing how we need a new synthesis, but never seeing any new alternatives.

    • old school
      Posted March 22, 2010 at 7:35 am | Permalink

      But Pigliucci and Co, despite (or because of)their expansive travels through philosophical territory DO present a description of a new synthesis for your inspection. It may just be larger and deeper than you think. Trees are nice, but you must consider the forest, too.

  2. Posted February 17, 2009 at 9:29 am | Permalink

    Oh, Jerry, here we go again with your “we already know everything, don’t need anything new” attitude. And frankly, picking on Carl isn’t very nice, he did a very good job in that article. Ok, I’ll post a response soon over at rationallyspeaking.org

    Emily, if you read a bit more widely than just Jerry’s blog you will see that there are plenty of papers and even books on what an Extended Synthesis consists of. And more are on their way.

  3. miko
    Posted February 17, 2009 at 7:57 pm | Permalink

    Doing evolutionary biology at the level of molecular genetics is very, very hard. Just doing genetics is so hard that, for example, drosophila biologists tend to throw away anything remotely complicated that pops out of a screen. If it doesn’t behave in a predictable, Mendelian fashion with a consistent phenotype when you outcross it, chuck it and stick to one of your 17 other mutants. I think it will be a long time before there will be any evidence-based evaluations of the import of things phenotypic plasticity in selection. Anything like this is a “bad project” in the sense that it’s too hard and risky for someone to gamble a thesis or postdoc on.

    Anyway, it’s seems a bit early to poo-poo any of these ideas (most of which are logically coherent) on what seem to be aesthetic grounds. Yes, there isn’t a lot of hard data supporting, say, the Baldwin effect…but I’ve never heard of anyone *seriously* looking for it. And, again, that’s seems to be just because it’s hard.

  4. Posted February 18, 2009 at 7:51 pm | Permalink

    Very interesting, yet at the same time leaves me wanting. This apparent “revolutionary” meeting should have made ripples since July 2008, no? Can anyone supply a “proceedings” of the meeting (or anything else for that matter)? I would be much obliged. This is all terribly interesting.

    Of course, all possible avenues of research deserve attention on this matter. Why the need for a formalized label of “extended” here? The rest of science simply adapts to new data/observation, why not evolution. Perhaps I just need to read more widely as well.

    Regardless, the exaggerated tone of journalists (Mazur) contributes very little for either argument.

    • whyevolutionistrue
      Posted February 19, 2009 at 2:23 pm | Permalink

      I believe the proceedings of the Altenberg meeting are going to be published by M.I.T. press. And yes, Suzan Mazur (read her numerous “Scoop” posts and interviews about how Darwinism is already dead) is a prime example of cockeyed and irresponsible journalism.

  5. windy
    Posted February 19, 2009 at 1:59 am | Permalink

    Doing evolutionary biology at the level of molecular genetics is very, very hard. Just doing genetics is so hard that, for example, drosophila biologists tend to throw away anything remotely complicated that pops out of a screen.

    What? There’s a bunch of stuff done on the genetics of complex traits in Drosophila.

    I think it will be a long time before there will be any evidence-based evaluations of the import of things phenotypic plasticity in selection.

    There are already studies on the genetics of phenotypic plasticity, too.

    Anyway, it’s seems a bit early to poo-poo any of these ideas (most of which are logically coherent) on what seem to be aesthetic grounds.

    No one is “poo-poo”ing phenotypic plasticity itself or any of those other things. The disagreement is whether it’s best to approach them as some kind of independent developmental phenomena or as evolving traits like any other.

  6. jacob
    Posted February 19, 2009 at 7:02 am | Permalink

    Yes, the literature on the adaptive significance of phenotypic plasticity is vast. In fact, phenotypic plasticity is probably the least controversial of any of the ideas of the extended synthesis. The question to me seems to be, do phenomena like plasticity, epigenetic inheritance, etc. fall neatly within the fold of the modern synthesis? Since the modern synthesis is fundamentally a theory of genes, epigenetic inheritance and environmentally contingent phenotypic expression seem to need a larger conceptual framework than the MS has to offer.

  7. miko
    Posted February 20, 2009 at 10:24 am | Permalink

    “What? There’s a bunch of stuff done on the genetics of complex traits in Drosophila.”

    Really? There are at best a couple hundred papers on PubMed that have anything to do with quantitative traits in Drosophila. This is for the premier animal genetics model, with tens of thousands of papers focused on its biology, the vast majority of which involve genetics. Drosophila geneticists, with very rare exceptions, study artificially induced, Mendelian, LOF alleles.

    “Yes, the literature on the adaptive significance of phenotypic plasticity is vast.”

    Again, really? Compared to what? I don’t even think the body of empirical research on the adpative significance of coding sequence mutations is anywhere near what could be called “vast,” so I guess I’m hard to please. Reviews and theorizing don’t count… data.

  8. windy
    Posted February 20, 2009 at 3:05 pm | Permalink

    Since the modern synthesis is fundamentally a theory of genes, epigenetic inheritance and environmentally contingent phenotypic expression seem to need a larger conceptual framework than the MS has to offer.

    So, lactose digestion in E. coli does not fit into the conceptual framework of the MS? It is after all an example of environmentally contingent phenotypic expression. One wonders how we’ve managed to scrape by these 50 years since the lac operon was discovered and the MS fell on its head… ;)

  9. miko
    Posted February 24, 2009 at 2:58 pm | Permalink

    I’m glad you mentioned the lac operon… here’s one feature of it that doesn’t fit into the MS – heritable phenotypic change from trancsriptional errors.

    http://dx.doi.org/10.1371/journal.pbio.1000044

  10. Luke
    Posted March 9, 2010 at 8:11 am | Permalink

    I think the MS needs to be expanded, but not ‘overhauled.’ It would be nice to get a new conceptual framework to bring all of the relatively new areas of research under one umbrella. The problem is with those people who, like the authors of “What Darwin Got Wrong,” believe that new concepts overwrite past understanding rather than expanding it.


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  1. [...] Evolutionary Biology 2009: Ann. N.Y. Acad. Sci. 1168: 218–228 (2009).   For a counterpoint see Are we ready for an “extended evolutionary synthesis”? « Why Evolution Is True. Eco World Content From Across The Internet. Featured on EcoPressed Just Add Water Share [...]

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