Bonobo apes have displayed a trait often described as uniquely human – helping strangers with no obvious expectation of receiving anything in return. The finding doesn't just confirm that bonobos really are our better selves, but sheds light on the origins of human altruism.
Simplistic interpretations of natural selection suggest we should only help others if they are our relatives, and therefore carry many of the same genes, yet most of us rely on the kindness of strangers, and complex societies could probably not work without it. Altruism in humans is given many explanations, and often claimed not to exist at all in animals.
Yet Dr Jingzhi Tan of Duke University put a hole in that theory four years ago by reporting bonobos will share food with strangers. In other words, this is not just the kindness to kin we are already familiar with, but a willingness to go out of their way to help members of the same species to which they have no connection – and who might even become competitors for resources.
Now Tan is back, with a new study published in Scientific Reports showing just how far the generosity of the species once called pygmy chimpanzees will go.
In the Lola ya Bonobo sanctuary in the Democratic Republic of Congo, Tan led 16 wild-born bonobos (mostly rescued orphans) one at a time into one of two rooms separated by a fence. A piece of apple hung from a rope so that the apes couldn't reach it, but could release a wooden pin causing it to drop into the other room.
Occasionally bonobos placed in this environment would climb the fence to release the fruit, even though this required them to stop playing with a toy they appeared to enjoy. When Tan brought another bonobo into the other room, the first bonobo was four times more likely to go to the effort of releasing the apple than when the second room was empty. Moreover, they didn't need to be asked, there was no difference in the rate of assistance when the set-up prevented the second ape from gesturing for help. There was also no difference based on the sex of the animals involved.