London Review of Books on EvoDevo. Gets it a bit wrong

Oh dear. What starts off as a musing on a small part of Wagner, rapidly turns into a discussion of evolution. Jerry Fordor (who?) wants to know why pigs don't have wings. He doesn't like natural selection. Which is a pity because while adaptationism is sometimes taken too far it still works and is still the most important driving force in nature.

Fodor doesn't like evolutionary psychology much. Fair enough, I'm not too keen on its excesses (like the recent non-study suggesting that girls prefer pink and boys blue). However it is not unreasonable to suppose that our behavioural patterns evolved in response to living on the savannah. As the majority of humans don't live in hunter-gather groups it isn't much of a stretch to suggest that some of the problems we have with modern life are because the behavioural modules that worked then don't work now.

Fodor distinguishes the two parts of "Darwinism", phylogeny and natural selection. (You can always tell if the essayist is going to get it badly wrong when they use the term "Darwinism" to describe modern evolutionary theory. I'd like to see a ban on the word outside of its historical context.) He then introduces the idea that adaptationism cannot explain everything, bringing up Sephen Jay Gould's analogy of the spandrels of San Marco. A spandrel is a triangular space which you get in the corners of arches when they are supporting a dome. They are often highly decorative.  If you support a dome with arches you automatically get spandrels. Similarly in biology there is debate about how significant natural selection is in producing a particular phenotype. Some people, like Larry Moran and the late Stephen Jay Gould see a greater role for mechanisms other than natural selection. Others such as Richard Dawkins and Simon Conway Morris don't think these ideas are useful. Nobody contends that natural selection is the be-all and end-all.

Except it seems Mr Fodor. Fodor also doesn't like the fact that artificial selection is a good analogy for natural selection because nature isn't conscious. 

               "How could a studied decision to breed for one trait or another be ‘the very same thing’ as the adventitious culling of a population?" 

Fodor asks. Well, because NS doesn't necessarily proceed by culling. All you need is for the organisms with that trait to have a couple more children in order for the trait to spread. As far as evolution is concerned having no kids is the same as being dead. Fodor has got rather too wrapped up in the "survival of the fittest" analogy to see that it isn't always like this.

              "The crucial test is whether one’s pet theory can distinguish between selection for trait A and selection for trait B when A and B are coextensive: were polar bears selected for being white or for matching their environment? Search me; and search any kind of adaptationism I’ve heard of. Nor am I holding my breath till one comes along."

Um, polar bears live in a predominately white environment. If they didn't maybe they wouldn't be white? Why bears might be white in a non-white environment is an interesting question however. (But not relevant to Fodor's thesis).

Fodor seems to think that evolutionary development is a far more important part of evolution than natural selection is, discussing why pigs don't have wings, and correctly surmising that they are constrained by their embryology. There's nowhere to grow them without radically redesigning the tetrapod body-plan. Organisms have all sorts of constraints placed upon them by their biology, and it makes it very interesting to see how they solve particular problems, or failed to develop particular solutions. Bats pterosaurs and birds sacrificed a pair of limbs to fly. Insects used a different solution and still retain all their original legs.

However this harks back to the old orthogenetic arguments of biologists like Cope, and others Wiliam Patten wrote that "Natural Selection cannot create it can only sift". Natural selection plus mutation can do all sorts of things.

The traits we see are the result of pre-existing constraints, fiddly bits that come along for the ride and are kept because they aren't harmful, all mediated through natural selection. If an evolutionary spandrel was harmful it wouldn't hang around very long. One of the most important parts of evolution is "stabilising selection"- keeping things the same because they work, and penalising deviations from the norm because they don't. This works in artificial selection too.

So, in all a mixed bag. It had the potential to be a good essay, but as so often happens the "Darwinism in crisis!!" angle has been massively overplayed, and Fodor seems to have thrown the baby out with the bathwater in his realisation that things are a littl emore ocmplex than they appear at first.