Bonobos might not be the saintly hippies we imagine

Alex Lee January 4, 2018

Generally, bonobos are known as the free-loving, co-operative apes of the primate world. Meanwhile, chimpanzees are typically viewed as aggressors more inclined to hit the war path. Whilst it’s been proven that bonobos are on the whole, selfless and voluntarily helpful to outsiders, a new study published in Current Biology throws a banana-shaped wrench in that simplistic picture of the bonobo.

The researchers, Christopher Krupenyee and Brian Hare of Duke University wanted to investigate whether bonobos’ friendly reputation meant that they preferred the company of cooperative helpers or dominant hinderers. Modelling their study over one conducted in 2007 involving human infants, the researchers showed bonobos two-dimensional animated shapes, one the helper and the other, the hinderer.

24 bonobos were shown videos on an iPad of a circle (the climber) trying to go up a hill and failing three times. On the third attempt, a blue triangle (the helper) entered the video and pushed the circle up to the top of the hill and then exited the frame. In a different video, a red square (the hinderer) entered the video from above and pushed the circle down the hill before exiting the frame. The bonobos were then asked to reach for a shape, either a red square or a blue triangle. In all cases apart from two, the bonobos chose the hinderer.

Here’s an example of one of the videos of helpful and destructive shapes:

In the second experiment involving 22 bonobos and real-life actors, the bonobos, on average, chose the hinderers more frequently. The bonobos watched an actor drop a toy out of reach, a helper picked up the toy and attempted to hand it back, but a hinderer prevented the transfer by snatching it away. The helper and hinderer then held out an apple to the bonobo and in a higher frequency of cases, the bonobos chose the hinderer’s apple.

In a third experiment, there was no demonstration and bonobos went up to experimenters voluntarily without food incentives. The experimenter which the bonobo went up to most was designated the role of helper. The bonobos were then shown the demonstration, and a significant switch from the bonobo’s preference of the helper to the other experimenter (the hinderer) was observed.

“Dominance is a powerful influence in many social species. We believe that bonobos show a preference for hinderers because hinderers appear to be dominant, and it’s always good to have dominant friends and allies,” Krupenye told Alphr.

The 2007 study proved that three-month old human infants already had a strong preference for helpers, choosing the helpers the majority of the time when faced with a similar task. The findings suggest that the human preference for helpers evidenced in the 2007 study only evolved after we diverged from other apes.

“Our findings highlight the nuances of the social and cooperative behaviour of bonobos,” Krupenye explained. “Bonobos exhibit a rich array of co-operative tendencies – like food sharing and alliances among females to thwart male aggression – but they aren’t the completely non-aggressive hippy ape that the media has often sold them to be,” he added.

Krupany and Hare are planning on looking at chimpanzees in the future. Who knows – maybe they’ll end up taking the bonobos’ peace-loving reputation by siding with the helpers?