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THERE was no doubt that the humpback whale saved the seal’s life, carrying it away on its chest and protecting it with its flipper from the onslaught of the killer whales. It was odd behaviour that marine ecologist Robert Pitman observed in the frigid Antarctic seas back in 2009 – but, it turned out, not uncommon. How you interpret it goes to the heart of an intense evolutionary debate: can any creature ever be truly altruistic?
A basic reading of evolution says no, because survival of the fittest means maximising your own reproductive success. Altruism, defined by philosopher Auguste Comte in 1851 as “intentional action, ultimately for the welfare of others, that entails at least the possibility of either no benefit or a loss to the actor”, is simply not a thing.
Things that look like it are widespread. Many animals act in ways that reduce their own reproductive success but benefit others. Some social insects, for example, give up reproduction entirely to support the colony.
One proposed explanation is kin selection: altruism persists because it helps the close relatives of nicer individuals to reproduce, which passes their own genes on too. Some form of this was probably at play with the humpback whale: by automatically chasing away orcas, regardless of what they were attacking, the humpback increased the survival chances of individuals in its pod.
David Sloan Wilson at Binghamton University in New York champions a different idea: group selection. This emphasises the reproductive success not of individuals, but of a whole group. “All you have to do is go up a little bit in scale, and there you …
