Last updated: May 5, 2012 12:11 am

The buzz word

Why is ‘eusociality’ – the altruistic behaviour common to bees and humans – so rare?

The Social Conquest of Earth, by Edward O Wilson, WW Norton, RRP£18.99, 352 pages

 

“Where do we come from? What are we? Where are we going?” Those famous questions, inscribed by Paul Gauguin in his giant Tahitian painting of 1897, introduce The Social Conquest of Earth. Their choice proclaims Edward O Wilson’s ambitions for his splendid book, in which he sums up 60 distinguished years of research into the evolution of human beings and social insects.

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Wilson has focused on the biology of behaviour since joining Harvard University as a junior research fellow in 1953. He also has a passion for writing, with 25 books to his credit (including two Pulitzer Prize-winners). The Social Conquest of Earth fully maintains the elegant and informative style of its predecessors.

His most influential book, Sociobiology (1975), defined a new discipline, with the message that social behaviour could only be understood through the lens of evolution. At that time the idea that genes and natural selection play such an important role in human society outraged many social scientists and people on the political left. By now the main messages of sociobiology and its offspring, evolutionary psychology, have been absorbed into the intellectual mainstream, though the nature-nurture debate rumbles on as scientists investigate the relative contribution of genes and the environment to various aspects of life.

Eusociality is the key word at the heart of The Social Conquest of Earth. In a eusocial species multiple generations live together, performing specialised roles that require collaboration and, sometimes, altruistic behaviour in which individuals go against their selfish interests for the benefit of the group.

Given the apparent competitive advantages of eusocial behaviour for the species, its rarity presents a serious scientific challenge. Advanced eusociality is found only in ants, bees, termites – and humans. And all these have been immensely successful. Wilson estimates that the world today contains 10 million billion living ants, with a combined body weight close to that of seven billion humans.

To explain why eusociality is so unusual, Wilson traces a series of evolutionary phases through which a species must pass en route to advanced eusocial behaviour. He shows that the chances of passing through all of them, as a result of Darwinian natural selection, are tiny.

The first step is the formation of groups within a freely mixing population of otherwise solitary individuals, normally around the building and defence of a nest. Then genetic changes begin to keep members of the group together. A vital element is suppression of the universal urge among animals to disperse and find new mates away from the parental nest as soon as they have grown up; a single mutation can have this effect in bees and wasps, recent research has shown.

At this stage, what Wilson calls “spring-loaded” genetic pre-adaptations can take effect. For example, natural selection may create an alerting system with alarm calls or chemical signals, so that insects can distinguish members of their own colony and draw nest-mates to newly discovered food. In the most advanced eusocial ants and bees, many evolutionary lines have contributed to extremely specialised and elaborate social systems – each colony working in effect as a “super-organism”.

Although human society differs in many ways from ants and bees, Wilson argues that some of the evolutionary principles learned from insect research can be applied to people. The most controversial issue here is exactly what supplements or over-rides “individual selection” – individuals competing in a selfish way – to create altruistic behaviour that benefits others or indeed the colony as a whole, even though an individual may lose the chance to pass its genes on to future generations.

The conventional explanation is “kin selection”, which holds that individuals only sacrifice themselves to the extent that their relatives – and therefore their own genes – benefit. Wilson espoused kin selection in Sociobiology but his thinking has moved on to a more inclusive “group selection” mechanism. This favours groups that work together altruistically, regardless of how closely related their members are.

Although there is a hot academic dispute between advocates of kin and group selection – and Wilson devotes much space in The Social Conquest of Earth to justifying his recent change of mind – I could not tell from reading the book quite what the fuss is about. Historically, eusocial evolution has always involved groups in which all the members have close family ties, whether bees swarming around their queen or a band of hominids (which palaeontologists tell us would have typically included about 30 people). It seems to me that under those circumstances the instinctive altruism and co-operation generated by kin and group selection come down to the same thing.

Nonetheless Wilson – still a Harvard academic – emphasises two-level selection. “Individual selection is responsible for much of what we call sin, while group selection is responsible for the greater part of virtue,” he writes. “Together they have created the conflict between the poorer and the better angels of our nature.”

A less simple but perhaps more accurate way of looking at human evolution might be to see it operating at several levels: the selfish gene (as originally promoted by Richard Dawkins), the cell, the individual, family and wider group. Whatever the mechanism, the challenge now is to extend the attitudes that we have inherited from group or family selection so that people abandon the negative aspect of tribalism and regard the whole world as their kin.

As Wilson puts it, “Our instincts still desire the tiny, united band-networks that prevailed during the hundreds of millennia preceding the dawn of history. Our instincts remain unprepared for civilisation.” Yet he delivers a surprisingly uplifting answer to Gauguin’s final question – based, he admits, as much as anything on “blind faith”.

“Earth, by the 22nd century, can be turned into a permanent paradise for human beings, or at least the strong beginnings of one,” the book concludes. “We will do a lot more damage to ourselves and the rest of life along the way, but out of an ethic of simple decency to one another, the unrelenting application of reason, and acceptance of what we truly are, our dreams will finally come home to stay.”

Clive Cookson is the FT’s science editor

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