About Rationally Speaking

Rationally Speaking is a blog maintained by Prof. Massimo Pigliucci, a philosopher at the City University of New York. The blog reflects the Enlightenment figure Marquis de Condorcet's idea of what a public intellectual (yes, we know, that's such a bad word) ought to be: someone who devotes himself to "the tracking down of prejudices in the hiding places where priests, the schools, the government, and all long-established institutions had gathered and protected them." You're welcome. Please notice that the contents of this blog can be reprinted under the standard Creative Commons license.

Thursday, June 29, 2006

Evolution, alive and well, thank you very much

The annual international meeting of evolutionary biology has just closed at Stony Brook University, and I'm happy to report that the field is alive and well – despite the fact that half of Americans think it's less scientific than astrology and threatens the survival of their very souls (whatever those are).

The meeting was organized by the Society for the Study of Evolution, the American Society of Naturalists and the Society of Systematic Biologists, the three premier organizations of professional evolutionary biologists. This year the gathering featured an unprecedented number of participants (close to 1500) and of parallel sessions (11), as well as a whole day public symposium on those perennial troublemakers, intelligent design creationists.

The impression I got from attending several sessions on topics such as natural selection, adaptation, evolutionary ecology and the evolution of development is that the field is at the moment an interesting mix of what philosopher Thomas Kuhn called “normal” and “extraordinary” science. Normal science works within an established paradigm, such as the so-called “synthetic” theory of evolution – a series of theoretical constructs formulated in the 1930s and 40s to expand Darwin's original insight and reconcile it with population and quantitative genetics. Normal science is about “puzzle solving,” according to Kuhn, i.e. scientists spend their time not by testing the basic assumptions of their theoretical framework (because it is considered solid enough), but applying such framework to the elucidation of specific problems. For example, nobody at the evolution meetings this year presented a paper testing the existence of natural selection, yet plenty of researchers used the concept of natural selection to inform their empirical investigation of what is happening in populations of fish, amphibians, insects, plants and so forth.

Despite most talks at this year's evolution meetings being about “normal” science, there were also hints here and there that some major change may be on the horizon. A few researchers devoted their time to rather exotic-sounding evolutionary mechanisms, such as genetic assimilation and epigenetic inheritance. While this is not the place to get into a detailed discussion of technical issues, these mechanisms have the potential of significantly augmenting the theoretical arsenal of evolutionary biological theory, adding so far unsuspected sources of variation and complexity to our understanding of the biological world. Epigenetic inheritance, for instance, is a phenomenon by which non-genetic material (e.g., methyl groups attached to the DNA, used by the cell as switches to signal which genes to activate or keep silent) can be replicated and passed from one generation to another. The phenomenon has been suspected for decades, and solid empirical evidence in favor of its existence is now fast accumulating. We still don't know how widespread epigenetic inheritance is, and we don't have a detailed theoretical framework to include it into standard evolutionary theory, but one gets the feeling that once such requirements will be fulfilled, the current paradigm in the field will be significantly altered.

Do these new potential developments represent the possibility of what Kuhn called a “paradigm shift,” that is a dramatic change in the way we understand evolution? I doubt it. In fact, biology is a clear example of a science that has proceeded at least since 1859 (the year of the publication of Darwin's “Origin of Species”) without any such shift. The fundamental Darwinian insights that all life on earth share a common descent, and that natural selection is a major mechanism of diversification of biological forms, are still valid and at the core of evolutionary theory. Yes, much has been added by modern population genetics, molecular biology, paleontology, and developmental biology – both empirically and conceptually. But none of these additions have in any way undermined the foundations of the Darwinian edifice. This is different from what happened in geology before and after continental drift was recognized, or in physics when Newtonian mechanics was superseded by Einstenian relativity. In fact, the last paradigm shift in biology – ironically enough – occurred when Darwin convincingly rejected William Paley's arguments for intelligent design as an “explanation” of biological diversity. That is why the modern intelligent design movement promises not an advancement of science, but a regress to a previous, scientifically unproductive, paradigm.


  1. Your comments on the epigenetic phenomenon as a possible explanatory factor for genetic diversity was fascinating, and would go a long way towards helping to explain how speciation could be so profligate.

    You know, of course, that the complex biochemistry responsible for epigenetic phenomena adds another layer of information to be ignored, misunderstood, scoffed at, or dismissed as "scientific mysticism" by creationists. It's ironic that the more we know about how evolution works, the less acceptable it becomes to religious creationists. They long for explanations that can be boiled down to Republican-sized, emotionally comfortable and intellectually lazy sound bytes.

  2. I am currently enrolled in an online graduate course in evolution. The program I am in in is generally excellent, (it is a program in life science for teaachers) but this course is disappointingly elementary.

    The thing is, there are a number of creationists in the course. Their simpleminded misunderstandings and silly falacies are just too much. I'm too tired to engage these idiotic straw men yet again.

    The sad fact is, the level of scientific literacy needed for all this superstitious crap to just go away is far, far away, if it ever does arrive.

  3. Ciao Massimo,
    Glad the conference was a success. Did you see the recent NY Times piece about the woman in GA who quietly fought to be able to continue teaching evolution in her life science class? Thought you might enjoy it.

  4. Genetic assimilation seems to be an interesting area, methinks.

    Now, what I'd like to see more is, instead of defenses of evolution, attacks against ID. You know, corner them a bit and try to get them to "explain" many things about ID's mechanisms, "theoretical bases", etc. Every single discussion I come across on the subject is always about what can and cannot, why or why not, etc. be explained by evolutionary biology. What about turning the tide a bit; it might make it clearer to more people that ID is completely void of any substance. One can hope.

    And after all, that's what they say: The best defense is a good offense - in spite of Italy's team in the World Cup, of course... ;-)


  5. j, I couldn't agree more. It's time to get off the defensive, quit defering to silly superstition, and make them _show_me_the_science!

  6. This may not be relevant to anything in particular, but yesterday I purchased Richard Dawkins' The Ancestor's Tale . It is the closest thing to a can't-put-it-down non-fiction work that I've ever come across. I love the fact that it's over 600 pages long. Gives me so much to look forward to.

  7. I know that some aspects of evolution have already been beaten to death on this blog. Nevertheless,

    I find this interesting.

  8. Thank you for this post! I am writing a research paper on just this- synthetic evolution as normal science. Very helpful.


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