Darwinian devolution

Gabby Dover hails the breaking of selfish geneticists' great taboo.

Some of the five books under review may come to be seen as a watershed in the study of evolution by natural selection. Four are pocket-books, part of a series titled Darwinism Today, the first two of which offer largely unsubstantiated assertions of the intellectual primacy of Darwinism as a gratifying explanation for our human condition and foibles, on the back of that particular dumbing-down tendency of militant Darwinism first propagated by Richard Dawkins with his selfish gene illusion. The fifth, by contrast, by Elliott Sober and David S. Wilson, is a tour de force about the multitrack selection processes that have shaped life's creatures, including human behaviour, that dispels once and for all that peculiarly mystifying belief among gene selectionists that "group selection" is risible and unworthy of intellectual consideration.

The contrasts in style - from assertiveness bordering on the ideological to systematic scientific analysis, from naive, off-the-wall conclusions to a healthy regard for the sheer complexity of the evolutionary process, especially as it applies to humans - highlight all that is bad and all that is good in contemporary evolutionary thinking. The pocket-book manifestos emerged from an adventurous run of seminars at the London School of Economics and are claimed by the LSE series editor to be written by leading figures in the field of evolutionary theory. This appeal to the high moral ground of theory, however, is at odds with the credentials of all but one of the authors and their dust-jacket advocates. The lack of real biological expertise among many commentators on evolution is becoming an increasing problem. I know of no other science whose main business and public image-making is carried out by retailers in second-hand intellectual property.

Colin Tudge, who has written the most readable of the four tracts and knows how to theorise inventively about early agriculture, is a science writer of sufficient modesty to limit his evolutionary assertiveness to just a few lines, which happen to be wrong ("natural selection disfavours toxic and spiky plants, if there were no need for them to be so " [my emphasis]) - another instance of the "fallacy of perfection" when trying to explain the mess produced by evolution.

An apparent absence of modesty and considerable misunderstanding of science, however, allow Kingsley Browne (professor of law) and Martin Daly and Margo Wilson (professors of psychology) to officiate on the Darwinian basis of human psychology to their hearts' content. But why should they be modest about the supposedly seamless explanatory power of natural selection when so many other agenda-setters have paved the way - enough to incite Ian McEwan (novelist) to declare publicly: "We are entering the heroic age of biology." He is right, of course, but for the wrong reasons. But what is McEwan supposed to think when the juggernaut of "evolutionary psychology" is driven by such simplifying and dated notions of evolutionary theory, mostly in the hands of practitioners from unrelated fields? If naming is required, so be it: Helena Cronin, philosopher (series editor); dust-jacketeers, Steven Pinker, linguist and sometime philosopher, Matt Ridley, journalist and writer, and Dawkins - Oxford University's professor of the public understanding of science. Exactly who he represents with his relentless just-so story-telling in support of his inside-out version of Darwinism is a mystery.

Of the pocket-book authors, only John Maynard Smith can be accepted as a true professional evolutionary theorist. He exhibits his usual flashes of original insight, although these are unevenly distributed in a rather tame treatment of that circle of interdependence: evolution - development - evolution. His tract stems from older debates originating in the 1970s, but those have been bypassed by the recent discoveries that development of form and behaviour is hopelessly incoherent. He dwells, too nostalgically for my taste, on issues of morphogenetic fields, self-organisation, and the dynamics of complex systems. Furthermore, his interpretations of new discoveries (which are clearly described) are invariably rooted in the functionalism of Darwinian selection without too much regard for other highly influential factors stemming from unstable, modular and redundant genomes and the vagaries of genetic drift.

Sober and D. S. Wilson, by contrast, are two of the leading thinkers in evolutionary biology who have made group selection respectable again and rescued altruism, and many other supposedly counter-intuitive behavioural traits, from that contortionist pot-pourri of selfish-genery, inclusive fitness theory and game theory.

Group selection versus gene selection is not an arcane academic squabble: it goes to the heart of an enormous battle being waged as to the causal factors underlying the great categories of Being. Are we at the mercy of genes, each and every one of which has selfishly propagated its own type via its manipulative hold on our behaviour? Or are we genetically conditioned as a group to behave as a group because group characteristics such as altruism are as capable of being selectively favoured as individual characteristics within a group, such as selfishness?

For Daly and Margo Wilson, group "greater-goodism" is an unworkable idea running counter to the selfish-genery version of evolved traits. They say that step-children have a rough time from their step-parents (which is not in doubt) because of the past genetic imperatives to invest in one's own genes, and not because they can be caught in a maelstrom of social and sexual tensions that may arise between two unfamiliar adults trying to start family life over again. For one recent BBC radio commentator, step-children face the "dark forces" of our genes - those supposedly freewheeling masters of the universe.

For evolutionary psychologists, as for Dawkins, group selection is taboo: it cannot be accepted as a level of selection pertaining to certain conditions complementary to, and interactive with, selection at the individual level (especially when the latter is further reduced to the vacuity of selection at the level of the gene). Group selection runs counter, ideologically more than genetically, to the selfish-gene mirage. Hence, in the context of selfish-genery, altruism becomes a Big Problem - defined by E. O. Wilson, the father of sociobiology, as "the central theoretical problem of sociobiology". Sober and D. S. Wilson, however, show convincingly how altruism can be maladaptive with respect to individual selection but adaptive with respect to group selection. Both modes of selection rely on a genetic contribution to the evolved behavioural trait; however, such a genetic influence does not imply that particular individuals are inevitably genetically programmed to be altruistic or selfish.

The selfish-genery explanation of altruism, and other so-called counter-intuitive behaviours, relies heavily on a heady mix of kin selection (as developed extensively by William Hamilton, evolutionary theorist) and game theory (as developed by Maynard Smith, among others). The irony of this reliance is that by 1975 Hamilton himself recognised the genetic feasibility of a group selection explanation for altruism, and as Sober and D. S. Wilson document, this Hamiltonian reconsideration has been under-valued for the past 20 years by Dawkins and his attendants. The best group selection can hope for is a grudging acceptance that it works in subdivided populations but must, by force, be marginal because (here comes another high-handed declaration) such populations do not naturally exist! This is a sad indictment of the extent to which the science of evolutionary biology can be persistently distorted and sidetracked into monolithic and unshakeable belief systems: what Sober and D. S. Wilson call the "paranormal".

As with Daly and Margo Wilson's demonstration that step-children are at risk, I have no quarrel with Browne's documentation that there are genetic contributions to the form and behaviour of humans, nor with the proposition that differences in the form and behaviour of men and women influence their long-term decisions over what each group, on average, wants out of life (work, family, relations, success, survival etc) - to the extent that there may be some, as yet unmeasured, biological basis to the so-called glass ceiling and gender-based pay differentials that affect working women. However, such possibilities cannot be based on the incorrect evolutionary genetics of Browne. An assessment of a genetic contribution to a behavioural trait based on heritability studies in twins does not mean that an observed difference in the average magnitude of the trait between men as a group and women as a group is genetically determined. We can have situations in biology ranging from one extreme of 100 per cent heritability within each group, with all the between-group difference in averages being due to the environment, to the other extreme of zero within-group heritability alongside a wholly genetically based difference in averages between groups. Browne knows something along these lines but then ignores his caution when advocating a genetically based evolved difference in given behaviours between the sexes as two distinct groups, just because there is a genetic basis to the behaviours in each individual, whether male or female.

His second mistake is to insist that male and female differences are due to differential reproductive strategies, given the supposed differences in parental cost-benefit calculations for investing in child rearing. This is back to selfish-genery and kin selection theory, ideas that themselves emerged from observations of differences in maternal and paternal contributions to the care of progeny in animal groups. From such derived theories, Browne repeatedly asserts that human sexual differences are predicted by evolutionary theory. So, round and round we go in circles: resurrect a theory based on observed sex differences, then interpret observed sex differences as predictions of the theory. But the self-justifying circularity of such "logic" does not mean that the theory is right. There are alternative theories, equally as evolutionary and genetic to boot, of which Sober and D. S. Wilson's group selection is one, that can explain the contentious premise of the "biological tragedy of women" (a loaded phrase cited by Browne).

There are many other so-called "universals" of human psychology that are explicable by a combinatorial variety of selection modes, including cultural selection. Additionally, there are emerging non-Darwinian (not anti-Darwinian) concepts for the establishment of evolutionary novelties emanating from the discoveries of genomic flux and developmental genetics whose contributions to the quirks of human behaviour need to be absorbed if we want seriously to engage in developing a comprehensive and unified theory of evolution. We need to move on from Darwin (most urgently from its dumbed-down version) as physics moved on from Newton. Darwin and Newton would surely welcome such progressive sophistication. There is more to evolution than natural selection, and more to human nature than evolution. Sober and D. S. Wilson's book is a step in the right direction towards a truly new Darwinism; Daly and Margo Wilson's and Browne's books are a step backwards, sadly without their realising it. Darwinism Today is clearly of its time: but if Darwin is to replace Marx and Freud at the top of the intellectual agenda, Darwinian thinking needs to be more scientifically comprehensive and less self-consciously polemical.

Gabby Dover is professor of evolutionary genetics, University of Leicester.