Wednesday, February 10, 2010

Fodor and Palmarini's critique of Darwin

What Darwin Got Wrong by Jerry Fodor and Massimo Piattelli Palmarini Darwin is under fire again, but Mary Midgley feels that his ideas have been misrepresented

Mary Midgley The Guardian, Saturday 6 February 2010

What Darwin Got Wrong by Jerry Fodor and Massimo Piattelli Palmarini 178pp, Profile, £20

Charles Darwin complained quite crossly in his autobiography that, despite many denials, people still kept saying he thought natural selection was the sole cause of evolutionary development. "Great is the force of misrepresentation," he grumbled. Had he known that, a century later, his alleged followers would be promoting that very doctrine as central to his teaching, and extending it into the wilder reaches of psychology and physics, he might have got even crosser. Darwin's objection was surely not just that he could see other possible causes. He saw that the doctrine itself did not make sense. No filter, however powerful, can be the only cause of what flows out of it. Questions about what comes into that filter have to be just as important. The proposed solution bears no proportion to the size of the problem.

Since his time, biologists have discovered a huge amount that is really interesting and important about internal factors in organisms that affect reproduction. This powerful little book uses that material to challenge sharply the whole neo-Darwinist orthodoxy – the assumption that, essentially, all evolution is due to mutation and selection. Its authors do not, of course, deny that this kind of classical natural selection happens. But they argue strongly that there is now no reason to privilege it over a crowd of other possible causes. Not only are most mutations known to be destructive but the material of inheritance itself has turned out to be far more complex, and to provide a much wider repertoire of untapped possibilities, than used to be thought. To an impressive extent, organisms provide the materials for changes in their own future. As the authors put it, "Before any phenotype can be, so to speak, 'offered' to selection by the environment, a host of internal constraints have to be satisfied." Epigenetic effects, resulting from different expressions of the same genes, can make a huge difference. And genes themselves are now known not to be independent, bean-like items connected to particular transmitted traits, but aspects of a most intricate process, sensitive to all sorts of internal factors, so that in many ways the same genes can result in a different creature. Recent work in "evodevo" – evolutionary developmental biology – shows how paths of development can themselves change and can change the resulting organism. And again, forces such as "molecular drive", which ­rearrange the genes, can also have that effect.

Besides this – perhaps even more interestingly – the laws of physics and chemistry themselves take a hand in the developmental process. Matter itself behaves in characteristic ways which are distinctly non-random. Many natural patterns, such as the arrangement of buds on a stem, accord with the series of Fibonacci numbers, and Fibonacci spirals are also observed in spiral nebulae. There are, moreover, no flying pigs, on account of the way in which bones arrange themselves. I am pleased to see that Fodor and ­Piattelli Palmarini introduce these facts in a chapter headed "The Return of the Laws of Form" and connect them with the names of D'Arcy Thompson, Conrad Waddington and Ilya Prigogine. Though they don't actually mention Goethe, that reference still rightly picks up an important, genuinely scientific strand of investigation which was for some time oddly eclipsed by neo-Darwinist fascination with the drama of randomness and the illusory seductions of simplicity.

This book is, of course, fighting stuff, sure to be contested by those at whom it is aimed. On the face of things, however, it strikes an outsider as an overdue and valuable onslaught on neo-Darwinist simplicities. (The one thing I would complain of is the title, which is perhaps too personal. This isn't just a point about Darwin; it's a point about the nature of life.) As the authors note, the traditional story has been defended by extending it – by widening the notion of natural selection to include some of these internal processes. But they think – surely rightly – that this device merely adds epicycles which kill the doctrine by ­diluting it. The long process of repeated trials and errors which has always been claimed as a central feature of natural selection cannot be incorporated in this way.

If we now ask what will take its place, their answer is that this question does not arise. There is not – and does not have to be – any single, central mechanism of evolution. There are many such mechanisms, which all need to be investigated on their own terms. If one finds this kind of position reasonable, the interesting next question is, what has made it so hard to accept? What has kept this kind of dogmatic "Darwinism" – largely independent of its founder – afloat for so long, given that much of the material given here is by no means new?

The explanation for this might be the seductive myth that underlies it. That myth had its roots in Victorian social Darwinism but today it flows largely from two books – Jacques Monod's Chance and Necessity (1971) and Richard Dawkins's The Selfish Gene (1976). Both these books, of course, contain lots of good and necessary biological facts. But what made them bestsellers was chiefly the sensational underlying picture of human life supplied by their rhetoric and especially their metaphors. This drama showed heroic, isolated individuals contending, like space warriors, alone against an alien and meaningless cosmos. It established the books as a kind of bible of individualism, most congenial to the Reaganite and Thatcherite ethos of the 80s. Monod first showed humans in Existentialist style as aliens – "gypsies" in a foreign world – and, by expanding the role of chance in evolution, concluded that our life was essentially a "casino". Dawkins added personal drama by describing a population of genes which – quite unlike the real ones inside us – operate as totally independent agents and can do as they please. It is no great surprise that these images caught on, nor that they can now persist whether or not the doctrines linked to them turn out to be scientific.