Darwin in the News

1/30/2010

Yesterday, I published a longish article in the Independent on a new Darwin book: What Darwin Got Wrong, by Jerry Fodor and Massimo Piattelli-Palmarini. The book is a heavy polemic against the Modern Synthesis or Neo-Darwinism. Their attack is both philosophcial and scientific and urgently required answering. Many biologists feel that the Modern Synthesis badly needs updating to include the welter of data coming from Evo Devo but What Darwin Got Wrong is way off target.

Inevitably, What Darwin Got Wrong will be heavily blogged. First off was evolutionary biologist Jerry Coyne. Watch this space.

Christopher Potter link

2/1/2010 10:21:41 pm

Dear Peter,
I very much enjoyed your review. I wish you had had more space in which to outline where you think the modern synthesis is in need of updating; because the point you do make is so interesting. What is the hard-line synthetic response to the problem of the mostly unchanging genes that describe body plan?
In your own book (if I remember correctly) you write of a caterpillar that looks like a small crocodile. It was Miriam Rothschild who worked out why this would have an evolutionary advantage, because to a high-flying predator it would be possible to read the caterpillar as a crocodile that much further away. (It makes me think of dimwit Dougal in Father Ted who thought that Father Ted's small model cows were real cows on the horizon.) But it is more difficult to explain how the caterpillar came to look so much like a crocodile. It is hard to think how looking a tiny bit like a crocodile could confer evolutionary advantage. If I read your book correctly, I seem to remember that you suggest at some point that may be there are deeply engrained patterns in nature that emerge wholesale from time to time. This seems entirely plausible given the unchanging chunks of DNA contained across all life.
I don't really fully understand why this debate is so acrimonious. Perhaps it isn't. In any case, if Jerry Coyne is a wholesale synthesist (is he?) then he seems very sympathetic to what you have to say. Though he hasn't addressed your point about the body-plan gene problem and I'd love to know what he has to say.

Peter Forbes

2/2/2010 04:23:54 am

Thanks, Xtopher. It could take another book to produce and adequate reply but here goes. Why so acrimonious? The Modern Synthesis became a dogma of almost religious intensity (as Margulis suggested). Although it seemed premature to announce a complete theory when nothing was known about how genes made phenotypes the hardline stance was maintained. In the 70s and 80s it got tangled up with politics: the antis (Stephen Jay Gould, Richard Lewontin etc) were all leftwing and claimed that the Neos were rightwing. Sociobiology exacerbated this divide. It seems disastrous to me that the schism was so not about biology a lot of the time.
What is the hardline Modern Synth response to body-plans? Blogging on his website, re my article, Richard Dawkins says: “How hox genes can be misrepresented as anti-Darwinian completely beats me”. That doesn’t get us very far. I think most Neo-Darwinians now say that they accept all of the findings of evo devo etc but that this is just the source of the variation, which is then subject to natural selection. But this seems inadequate. It is the source of novelty we are looking for, not the pruning mechanism. What the evo devo people are saying is that the conserved bodyplan genes quite easily find new binding sites and create novelty. And that by changing the timing of regulatory genes you can get quite large changes in form. And there are body plans, such as the armour in sticklebacks which are easily switched on and off in different environments. And there may be other cryptic patterns that can be quite easily evoked. A book that explains all this is The Plausibility of Life by Marc W. Kirschner and John C. Gerhart. It’s quite hard going and for me only really takes off towards the end but it suggests a way forward.
Interestingly, Dawkins suggests on his blog that Mayr’s remark (futile to look for homologous genes) was said more in sorrow than anger: eg, wouldn’t it be lovely if we could find similar genes in different creatures but, alas, it’s not likely. I read this differently. No homologous genes is a prediction from the Modern Synth. If evolution were a matter of cumulative small variations plus aeons of time you would expect all the genes to diverge greatly, just as the English language is now unrecognizable from Anglo-Saxon. But we’ve found genes homologous to human genes in the boiling-water tolerant archaeobacteria of Yellowstone Park– we diverged 3 bn yrs ago. Since prediction and falsifiability is the essence of science I do take homologous genes to be a huge blow against the Modern Synthesis.

Christopher Potter link

2/3/2010 08:58:58 pm

Now I get it. So I suppose one of the big questions is how the different timing sequences on the hox genes get switched on and off. I imagine the Dawkins camp would say that natural selection will prove to be enough of an explanatory force, and the evo devo faction say that something else is required. I suppose those that say something else is required are always going to be on the weaker side if they don't have an idea what that something looks like. It's rather like those who think that to explain consciousness requires the existence of some new force field. It may well do but until someone tells us what that force field looks like and what some of its properties are then such a view is always going to be marginal. Marginal doesn't mean wrong of course. That's how science often advances, those in the wilderness have to stay there until they have sufficient weaponry to enter the fray. A shame that it always seems to get so nasty. If only scientists could 'whisper results' to each other as Keats suggested. Perhaps the warrior-like nature of science is an aspect of its being historically male dominated. It's got into some sort of cycle it can't break out of.
You'd think, by the way, that biologists would grasp firmly anything that looked like falsification. Falsifiable statements are not thick on the ground in this science. In the last fifty years we've seen biology develop in a testable science like physics. This issue around hox genes is surely hugely significant.

Peter Forbes

2/8/2010 07:00:30 pm

I don't really think it is a matter of "somethign else is required". Pattern making begins in chemical self-assembly. Natural selection is not in itself an explanation of form. DNA did not form a helix by trial and error any more than snowflake crystals form by trial and error. How selection acts on the processes of morphogenesis is being worked out in many cases. The best update I know on all this is Nick Lane's Life Ascending, just out in paperback.

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