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January 30, 2008

Hopeless Monsters

Carl Zimmer in his brilliant blog, The Loom:

How do new kinds of bodies evolve? It's a question that obsesses many scientists today, as it has for decades. Yesterday, Olivia Judson, an evolutionary biologist and book author, published a blog post entitled "The Monster is Back, and It's Hopeful," in which she declared that these transitions can happen in sudden steps.

Even before I had finished reading Judson's piece, I got an email from the prominent evolutionary biologist Jerry Coyne grousing about it. Coyne, who teaches at the University of Chicago, is an expert on the genetics of adaptation as well as the origin of new species. He has written potent, eloquent attacks on creationism in places like the New Republic (pdf). Recently he has also begun to express skepticism about the grander claims for evolutionary developmental biology--"evo-devo" for short (see this pdf for more).

I thought it would be interesting to hear what Coyne had to say--at length. Since he does not (yet) have a blog of his own, I invited him to write a guest post for The Loom. He kindly sent in the following piece, which appears below the fold, entitled "Hopeless Monsters." Please give Dr. Coyne a warm welcome to world of science blogging, and let him know what you think in the comment thread.

More here.

Posted by Abbas Raza at 06:16 PM | Permalink

Comments

If you read Coyne's article, you should probably also read this by Bora Zivkovic. Teaser:

Unfortunately, in bashing Judson along with making legitimate points (how many people will ignore this caveat in their responses?), Coyne ends up being more wrong than she is. And his intended audience is, arguably, better scientifically educated than hers - it's the Scienceblogs.com readers, not NYTimes. While bashing her head into a rock, Jerry makes visible his emotional enmity towards everybody who has a bigger picture of evolution than he has and has at their disposal both a methodological and a conceptual toolkit that Jerry lacks.

Posted by: bill | Jan 30, 2008 9:12:40 PM

It's not too clear to me what specifically Bora Zivkovic is objecting to in Coyne's article. For instance, Zivkovic approvingly links to this post by PZ Myers, but Myers shoots down the idea of evolution proceeding by beneficial macromutations too:

One point that Coyne handles well: there is a disconnect between the magnitude of genotypic changes and phenotypic effects — a single point mutation can cause amazing morphological changes. As Coyne points out, though, although this can happen, it's not likely to be a major force in evolutionary change. Dramatic, single-step phenotypic effects are the kinds of things that geneticists select for, but they are also exactly the kinds of things that nature selects against. Evolution is much more likely to sidle up towards a major change by successive smaller steps, since those small changes are less likely to be accompanied by major deleterious side effects. Also, phenotypic outcomes of development should be robust to be advantageous, which typically means that there are many regulatory events cooperating to produce them — and they are therefore buffered by multiple controls.
...

The "hopeful monster" concept was not shot down by the synthesis — it was ignored. I think it's been dismantled by developmental biology, though; what we've learned is that the stable morphological types we see in a single species are not simply fortunate stable nodes in a nucleus that can be tuned in different ways, but that each are the product of many generations of slow sculpting by the processes of evolution, and that they are riddled with clumsy kluges that aren't the outcome of some elegant global pattern switching mechanism, but of a long history of small tweaks.

PZ Myers does suggest that Coyne is being unfair to scientists working in evo-devo by suggesting that they themselves see their work as supporting the "hopeful monsters" concept, and also says that Goldschmidt's idea wasn't so implausible for his time, but these are just arguments about Coyne misrepresenting certain scientists, not about him misrepresenting what the current scientific evidence tells us about hopeful monsters.

Posted by: Jesse M. | Jan 31, 2008 2:50:34 AM

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January 30, 2008

Hopeless Monsters

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