Babysitting wasps that support extended families could help solve riddle of altruism, scientists say

Workers fly to nearby nests to help out needy neighbours, writes Tom Embury-Dennis

Paper wasps are models for understanding the evolution of altruism (P Kennedy)

Wasps help their poorer extended families by babysitting at nearby nests, biologists have observed in a discovery that may help solve the riddle of altruism in nature.

By closely watching 20,000 baby paper wasps and their carers on colonies around the Panama Canal, the research team showed that workers became less useful as the number of wasps in a colony rises, due to all the extra help.

Workers on larger colonies will as a result fly to their more needy neighbours’ nests.

“These wasps can act like rich family members lending a hand to their second cousins. If there's not much more you can do to help your immediate family, you can turn your attention to the extended family,” said biologist Patrick Kennedy, lead author and research fellow at the University of Bristol.

Similar principles of diminishing returns might explain acts of altruism in other social animals, added co-author Andy Radford, a behavioural ecologist also at the University of Bristol.

Since Charles Darwin first posited evolution in the 19th century, scientists have puzzled over why altruism develops in animals, as acts of selflessness outside the immediate family appear counterproductive to passing on genes.

Legendary biologist William Hamilton, who studied animal altruism, was left baffled in the 1960s by the paper wasps’ flying off to help less closely related neighbours.

But Dr Radford said: “By helping more distant relatives who are more in need - those living next door with fewer carers - workers can pass on more copies of their genes overall.”

Such behaviour in wasps is additionally surprising because they are usually extremely hostile to outsiders.

“We ended up being stung a lot. But it was worth it, because our results show that worker wasps can become redundant at home. A wasp on a colony with few larvae but lots of other workers becomes almost useless: the best thing to do is to babysit the larvae of other relatives,” said Dr Kennedy.

Previous work by co-author Seirian Sumner, professor of behavioural ecology at University College London, showed over half the worker wasps in Panama were helping on multiple nests.

“Wasps offer amazing windows into the evolution of selflessness. There is so much going on in a wasp nest: power struggles, self-sacrifice, groups battling against the odds to survive ... If we want to understand how societies evolve, we should look more deeply at wasps,” she said.