Over at the Guardian, Oliver Burkeman, a writer who apparently knows nothing about evolution, has a long piece called “Why everything you’ve been told about evolution is wrong.” Everything? Really? Burkeman seems to have a beef with Richard Dawkins, and seems to take delight in how the new “evolution revolution” would vex him:
What if Darwin’s theory of evolution – or, at least, Darwin’s theory of evolution as most of us learned it at school and believe we understand it – is, in crucial respects, not entirely accurate? Such talk, naturally, is liable to drive evolutionary biologists into a rage, or, in the case of Richard Dawkins, into even more of a rage than usual.
Well, maybe Burkeman’s insistence that popular notions about evolution are all wrong is just journalistic puffery. So what is the new finding that overthrows Darwinism?
There are several definitions of “epigenetics” (it once meant simply “development”), but Burkeman uses the term in its more modern sense as “inheritance not based on coding changes in the DNA.” Burkeman cites a couple of recent studies in which nongenetic, developmentally caused changes in an organism (like alterations in physiology due to starvation) can be passed on to one or two generations of its descendants. The offspring of stressed Swedish chickens, for example, have difficulty navigating mazes. He gives another two-generation example of epigenesis from humans.
This thin evidence, apparently, is why modern evolutionary theory is wrong. And so Burkeman gets in another slap at not only Dawkins, but Daniel Dennett:
As years of bestselling books by Dawkins, Daniel Dennett and others have seeped into the culture, we’ve come to understand that the awesome power of natural selection – frequently referred to as the best idea in the history of science – lies in the sheer elegance of the way such simple principles have generated the unbelievable complexities of life. From two elementary notions – random mutation, and the filtering power of the environment – have emerged, over millennia, such marvels as eyes, the wings of birds and the human brain.
It not be immediately obvious why this has such profound implications for evolution. In the way it’s generally understood, the whole point of natural selection – the so-called “modern synthesis” of Darwin’s theories with subsequent discoveries about genes – is its beautiful, breathtaking, devastating simplicity. In each generation, genes cause random mutations, making offspring subtly different from their parents; those mutations that enhance an organism’s abilities to thrive and reproduce in its own particular environment will tend to spread through populations, while those that make successful breeding less likely will eventually peter out. Yet epigenetics suggests this isn’t the whole story.
All I can say to this is: “Profound implications my tuchus!” There are a handful of examples showing that environmentally-induced changes can be passed from one generation to the next. In nearly all of these examples, the changes disappear after one or two generations, so they couldn’t effect permanent evolutionary change. The proponents of epigenesis as an important factor in evolution, like Eva Jablonka and Marion Lamb, always wind up talking about the same tired old examples, like cases of coat color change in mice and flower pattern in toadflax. I am not aware of a single case in which an adaptive change in an organism—or any change that has been fixed in a species—rests on inheritance that is not based on changes in the DNA. (For a refutation of the pro-epigenesis arguments that Jablonka and Lamb make in their 2005 book, see Haig .)
Moreover, some examples of “nongenetic” inheritance that do have adaptive significance, such as differential methylation of paternal versus maternal chromosomes, ultimately rest on changes in DNA that promote that differential methylation. And this “inheritance” lasts only one generation, for the methylation profile is reset in each sex every generation.
In contrast to the very few cases of one- or two-generation inheritance that cause nonadaptive changes in the phenotype stands the very, very large number of studies in which inherited changes within and among species map to the DNA. These include every case of evolutionary response to artificial or human-generated selection, adaptive changes within species (e.g., spiny-ness in sticklebacks), and differences among species in both morphology (e.g., the color differences in fruit flies I study) and reproductive barriers (the many mapping studies of “hybrid sterility” and “hybrid inviability” genes). Burkeman, of course, doesn’t mention these cases: it would ruin his nice story.
If we look just at studies of the inheritance of organismal changes that have evolved over time (and many of these would have detected profound epigenetic effects), the score would be something like this: DNA 757, Epigenesis 0. (I’m just making these numbers up, of course, to make a point.) If we look at all “inherited changes”, regardless of their evolutionary importance, we would have a handful of epigenetic changes versus literally thousands of DNA-based changes. So how can Burkeman say that epigenesis will profoundly revise our view of evolution?
Now I’m not saying that epigenesis was completely unimportant in evolution. Prions (cases in protein shape that don’t reflect changes in protein sequence), for example, could be considered cases of epigenetic inheritance, and might have played a role in the evolution of some species. What I am saying is that there is virtually no evidence that epigenetic inheritance has been important in evolution, and that the phenomenon seems, at this point, seems too infrequent to warrant rethinking the tenets of neo-Darwinism.
Burkeman notes that epigenetic inheritance appears to refute one of the prime tenets of evolutionary psychology: the idea that DNA-based changes in human behavior evolved by natural selection:
And now, if epigenetics and other developments are coming to suggest that environment can alter heredity, the very terms of the debate – of nature versus nurture – suddenly become shaky. It’s not even a matter of settling on a compromise, a “mixture” of nature and nurture. Rather, the concepts of “nature” and “nurture” seem to be growing meaningless. What does “nature” even mean if you can nurture the nature of your descendants?
Now, I’ve been a critic of the excesses of some evolutionary psychologists, but it’s simply insane to dismiss that field—and, by extension, the entire field of behavior genetics—because there is some thin evidence for inheritance of acquired traits.
Inevitably, Burkeman got wind of Jerry Fodor and Massimo Piattelli-Palmarini’s new book, What Darwin Got Wrong, a profoundly misguided critique of natural selection. Burkeman notes, correctly, that the book has met with fierce opposition from philosophers and biologists, but insists that it still has value:
It would be jawdroppingly surprising, to say the least, were Fodor to be right. A safer, if mealy-mouthed, conclusion to draw is that his work acts as an important warning to those of us who think we understand natural selection. It’s probably not a bankrupt concept, as Fodor claims. But nor should laypeople assume that it’s self-evidently simple and exhaustively true.
Probably not a bankrupt concept? Not self-evidently simple? (It is—that’s one of its beauties!) Not exhaustively true? (What does that mean? Is there any explanation for adaptation other than natural selection? Fodor has certainly never given one.)
Burkeman’s article represents the most self-serving, lazy, overblown, and irresponsible strain of science journalism. He lays out strong charges against modern evolutionary biology, and then doesn’t bother to consult a single expert to see if those charges stick. He touts epigenesis to the skies, but doesn’t bother to find out whether its proponents may have exaggerated its evolutionary importance. (That wouldn’t have required much digging!) Burkeman apparently lacks the ability to adjudicate claims and controversies in biology. Granted, we don’t expect all journalists to be able to do this, but if you don’t know what you’re talking about, you ask the experts.
Finally, Burkeman is not even a science writer—he’s a “features” writer. What business does he have telling the public that everything they know about evolution is wrong? He appears to be motivated far more by an animus against Richard Dawkins, and a desire to write catchy and sensationalistic science journalism, than by a desire to get the facts.
Burkeman is an ignorant fool. He belongs not at the Guardian but on page 3 of the Sun, where he can exaggerate and hyperventilate to his heart’s content.
UPDATE: The Guardian is backpedaling: there’s been a rebuttal piece posted on the Guardian’s own Comment is Free site (for the link, see Matthew Cobb’s comment #15 on this post).
Jablonka E, and M. Lamb M. 2005. Evolution in four dimensions: genetic, epigenetic, behavioral and symbolic variation in the history of life. MIT Press, Cambridge, MA
Haig, D. 2007. Weissman Rules! OK? Epigenetics and the Lamarckian temptation. Biology & Philosophy 22:415-428