Proposes New Theory of Social Evolution

The dominant evolutionary theory for Earth’s most successful creatures, and a proposed explanation for human altruism, is under attack.

For decades, selflessness — as exhibited in eusocial insect colonies where workers sacrifice themselves for the greater good — has been explained in terms of genetic relatedness. Called kin selection, it was a neat solution to the conundrum of selflessness in what was supposedly an every-animal-for-itself evolutionary battle.

One early proponent was now-legendary Harvard biologist E.O. Wilson, a founder of modern sociobiology. Now Wilson is leading the counterattack.

“For the past four decades kin selection theory … has been the major theoretical attempt to explain the evolution of eusociality,” write Wilson and Harvard theoretical biologists Martin Nowak and Corina Tarnita in an August 25 Nature paper. “Here we show the limitations of its approach.”

According to the standard metric of reproductive fitness, insects that altruistically contribute to their community’s welfare but don’t themselves reproduce score a zero. They shouldn’t exist, except as aberrations — but they’re common, and their colonies are fabulously successful. Just two percent of insects are eusocial, but they account for two-thirds of all insect biomass.

Kin selection made sense of this by targeting evolution at shared genes, and portraying individuals and groups as mere vessels for those genes. Before long, kin selection was a cornerstone of evolutionary biology. It was invoked to explain social and cooperative behavior across the animal kingdom, even in humans.

But according to Wilson, Nowak and Tarnita, the great limitation of kin selection is that it simply doesn’t fit the data.