UPDATE: I forgot to add a good piece by Steve Pinker which is required reading if you’re being seduced by the idea of group selection. “The false allure of group selection” is published on the Edge website. It’s followed by an online “discussion” involving 23 Edgies.

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E. O. Wilson has a new book out, The Meaning of Human Existence, which I’ve mentioned briefly (I haven’t read it). Last year he published another book, The Social Conquest of Earth, which I reviewed in the Times Literary Supplement (TLS; reference below). Since TLS reviews are behind a paywall, but I retain the copyright, I’ve decided to post it here, for I see Wilson was already developing themes in that book that he continues in the new one. In particular, note what I summarize in the second paragraph, which seems like the nucleus of Wilson’s new book.

Be aware that there is one new paper that claims to find group selection in colonial-nesting spiders, so my statement below that there are no examples of the process in nature may be revised someone (but only to the extent that we have one possible example of the process). It’s a complicated paper, and I’ll report on it when I’ve had time to read and digest it.

This is a bit longer than my usual posts, but since readers seem to object to “the fold,” I won’t use that device further except in rare circumstances.

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GENES FIRST

Jerry. A. Coyne

The reigning expert on social insects–particularly ants –Edward O. Wilson is best known to the public for his work on the evolution of social behaviour in humans and other animals, and for his unflagging efforts to conserve natural environments and biological diversity. His book Sociobiology: The New Synthesis (1975) was a milestone in applying evolution to sociality, creating a zeitgeist that helped spawn the field of evolutionary psychology.

In The Social Conquest of Earth, Wilson sets out to explain what makes us human, and to answer the fundamental questions of where we come from, what we are and where are we going. He is clear on where the answers lie: not in philosophy or the humanities, and certainly not in religion, which he sees as purveying “unsupportable claims about supernatural causes of reality”. No, the answers must come from biology, since, to Wilson, human nature is essentially a product of evolution. And he sees the most critical aspect of human nature to be our conflicted status as both selfless and selfish creatures. While we may intercept bullets to save our loved ones, co-operate to build houses for the homeless and drop money in a beggar’s cup, we also cheat on our spouses and our taxes, and battle with others for money and status. How can evolution explain these contradictions?

Wilson argues that these conflicting tendencies result from fundamentally different forms of natural selection. Explaining selfishness is simple: it’s the product of traditional Darwinian “individual selection” in which genes that helped our ancestors outcompete other individuals—to eat more food, find better mates, or simply kill each other— would leave more copies than genes promoting self-sacrifice.

But how, then, could altruism evolve? Behaviours that involve sacrificing your life or reproductive ability for others would seem to contravene natural selection, which, after all, involves leaving more descendants than others. An important caveat here is that cooperation is not the same thing as altruism. Many forms of co-operation produce immediate benefits to the co-operator and so can evolve by classic natural selection on individuals. Female lions hunting together, for instance, can kill larger prey and eat more meat per individual than solitary hunters can. A fish that belongs to a school is less liable than a solitary fish to wind up as a predator’s lunch. Many aspects of group living confer such direct benefits, so “selfish genes” don’t invariably produce selfish behaviours.

To explain “true” altruism, in which individuals risk their lives and reproduction for others, evolutionists have suggested two scenarios. Though these are widely accepted by biologists, The Social Conquest of Earth flatly rejects both. The first, “kin selection”, is based on the simple fact that relatives share genes. This means that genes promoting costly altruistic behaviour in their carriers can sometimes spread because they promote the survival of gene copies in relatives. A gene that made me lay down my life to save three brothers, for instance, would leave more copies than an alternative gene favouring self-preservation. The idea of kin selection has been enormously productive in evolutionary biology, explaining not only altruism towards relatives, but behaviours as diverse as parent–offspring conflict, sibling rivalry, spite, animal dispersal, and virulence in disease-causing microbes.

The second process, “reciprocal altruism”, involves the short-term sacrifice of some benefits for the sake of forming longer-term relationships with others who ultimately return greater benefits. If you give your surplus food to others or lend them money in times of hardship, they might return the favour when it’s your turn to be needy. Because such behaviours give net benefits to each partner, they can also evolve via standard natural selection. But you’d expect to see them only in species in which individuals can recognize and remember who is helpful and who is not – or something equivalent such as occupying a stable patch of ground that acts as a proxy for individual recognition. This is indeed the case: reciprocal altruism, involving acts like sharing meat and forming coalitions, is seen in primates like baboons and chimpanzees that live in fairly stable groups.

Having used these ideas in the past to explain social behaviour in animals, in The Social Conquest of Earth Wilson abandons them completely in favour of an older, and largely discredited, evolutionary scenario: “group selection”. According to this view, entire groups of animals compete with other groups for dominance within a species. Under certain conditions this can promote the evolution of traits, like altruism, that are seemingly bad for individuals but good for the group. To the new Wilson, this is the wellspring of our better nature: “Nevertheless an iron rule exists in genetic social evolution. It is that selfish individuals beat altruistic individuals, while groups of altruists beat groups of selfish individuals”. And he sees group selection as a cause of more than just altruism: it’s supposedly responsible for human traits like communication, complex culture, morality, tribalism, notions of duty and honour, and even religion and homosexuality. As the blurb proclaims, “group selection can be the only model for explaining man’s origin and domination”.

Although Wilson pushes this view hard – it’s the book’s centrepiece – he is probably wrong. Most biologists have rejected group selection for two reasons: it doesn’t work well in principle, and, more important, there’s no evidence that it has been of any significance in evolution. For an obvious reason, selection among groups is far less efficient than selection among genes: genes replicate and replace other genes much faster than groups of individuals divide and replace other groups. Evolving all the social traits on Wilson’s list via group selection requires a slow and unrealistic sequence of episodes in which human populations replaced each other, each replacement based on one or a few behaviours. Further, once group selection fixes a disadvantageous trait like altruism within our species, individual selection proceeds to undo it within populations (“selfish individuals beat altruistic individuals”). In other words, altruism that evolved by group selection is unstable and should disappear.

If the better angels of our nature really are based on genes that evolved – rather than on non-genetic aspects of culture – then they are much more likely to have done so by individual than by group selection. This becomes even more plausible with a more detailed look at how human altruism really works. It is preferentially directed towards friends and relatives, there is much concern with reciprocity and one’s own reputation, and psychological studies show that we dislike cheaters who hurt us personally much more strongly than we dislike cheaters who hurt our group. Such behaviours are precisely what you’d expect if altruism evolved by individual rather than group selection. But Wilson ignores these problems.

It is not even clear that altruistic groups of humans would beat non-altruists. Steven Pinker has noted that success of one group over another in the real world is based not on higher frequencies of altruistic individuals, but on matters like harsher discipline, better technology, and more brutal ideology. Indeed, altruistic groups may be more easily defeated because their empathy for the weak makes them susceptible to domination. But the most important problem is this: I know of not one evolved behaviour in any species that is harmful to individuals and their genes but good for their social groups. In the end, Wilson’s invocation of group selection is superfluous.

While the bulk of The Social Conquest of Earth is about human nature, a good chunk deals with Wilson’s personal area of research: the social insects, particularly those “eusocial” ones, like bees and ants, that show a division of labour between “castes” and have a fertile queen whose brood is raised by sterile female workers. The parallel with human culture here is the altruism of the workers, who sacrifice their own reproduction for the sake of their mother’s.

Virtually all evolutionists see eusociality as the product of kin selection. By helping their mother produce fertile brothers and sisters, sterile workers can actually leave more copies of their genes than if they reproduced themselves. This explanation has in fact been tested and confirmed several times. Despite that, Wilson still prefers a combination of individual and group selection, rejecting kin selection not just in this case, but in general: “The foundations of the general theory of inclusive fitness based on the assumptions of kin selection have crumbled, while evidence for it has grown equivocal at best. The beautiful theory never worked well anyway, and now it has collapsed”. He’s wrong on all counts.

Wilson (with two co-authors) proposed his alternative view of sociality in insects in a paper that appeared in the journal Nature in 2010. It was immediately criticized in five published letters signed by 156 authors –including almost every luminary working on the evolution of social behaviour – which emphasized the value of kin selection and the intellectual sterility of Wilson’s group-selection approach. (I was among those critics.) Wilson fails to mention this criticism in The Social Conquest of Earth. For a scientist trying to explain what we know about human evolution, ignoring such serious dissent is not only self-serving but irresponsible.

Wilson’s book, however, is not devoid of merit. There are interesting titbits about biology and anthropology, including fascinating descriptions of how diverse cultures divide up the colour spectrum in similar ways, and how incest taboos, which avert genetically based birth defects, are enforced even by cultures that don’t understand the genetic consequences. Yet the good bits are ultimately scuppered by Wilson’s attempt to feed questionable biological ideas to the public while ignoring the criticisms of his peers. The result is that readers will be seriously misled about human evolution and the evolution of social behaviour as a whole.

It is puzzling that, at the end of a distinguished career, Edward Wilson has chosen to repudiate fertile and long-standing ideas about evolution in favour of alternatives that are deeply flawed. His immense achievements have made his legacy secure, but it will be tarnished by this misguided attempt to explain social behaviour in insects and humans.

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Coyne, J. A. 2013. “Genes first” (Review of The Social Conquest of Earth by E. O. Wilson). Times Literary Supplement 4731 (1 Feb. 2013), p. 32.