John Maynard Smith

‘Natural history’ is seen by some professional biologists as hardly deserving to be regarded as a part of science. Compared to the experimental sophistication of molecular biology, and the apparent generality of its conclusions, natural history is no more than a collection of particular facts of little theoretical or practical import. There are two reasons why one should dissent from this judgment. The first is that the task of biology is to explain the living world, and that world is irreduciby complex. If I am interested in molecular biology – and I am – it is because it helps to explain how that complexity arose. A biologist who was not interested in the diversity of living things would be like a historian who did not care what had actually happened in history, and confined his attention to the study of experimental psychology.

The Extended Phenotype is a sequel to The Selfish Gene. Although Dawkins has aimed his second book primarily at professional biologists, he writes so clearly that it could be understood by anyone prepared to make a serious effort. The Selfish Gene was unusual in that, although written as a popular account, it made an original contribution to biology. Further, the contribution itself was of an unusual kind. Unlike David Lack’s classic Life of the Robin – also an original contribution in popular form – The Selfish Gene reports no new facts. Nor does it contain any new mathematical models – indeed it contains no mathematics at all. What it does offer is a new world view.

Pandas are peculiar bears, which spend most of their days munching bamboo. To do this, they strip off the bamboo leaves by passing the stalks between their flexible thumb and the remaining fingers. But how can a panda have an opposable thumb, when in bears the thumb lies parallel to the fingers, and inseparable from them? In fact, the panda does not have a proper thumb at all: it has five parallel digits just like other bears. The apparent ‘thumb’ is a modification and extension of a small bone in the wrist. For Stephen Gould, this is a particular and fascinating fact, but it is also an illustration of a general principle. The principle is that evolution proceeds by tinkering with what is already there, and not by following the canons of optimal design. Had the panda been designed by the Great Artificer, He would not have been constrained to make its hand by modifying the hand of a bear, and would doubtless have come up with a more elegant, if less entertaining solution to the problem of stripping bamboo.

I think I can see what is breaking down in evolutionary theory – the strict construction of the modern synthesis with its belief in pervasive adaptation, gradualism and extrapolation by smooth continuity from causes of change in local populations to major trends and transitions in the history of life.