Bonobos are gentle and cooperative creatures. Their social structure is matriarchal and relatively peaceful, they work together to obtain food and have been known to share snacks—even with strangers. But as Amina Khan reports for the Los Angeles Times, a surprising new study suggests that bonobos don’t gravitate towards helpful figures. Instead, they prefer bullies.
Researchers at Duke University sought to find out if bonobos place as much value on “prosocial” behavior (or actions that reinforce social bonds) as one of their closest relatives: humans.
Bonobos share about 98 percent of their DNA with humans, who are an intensely prosocial species. From a very early age, human babies show preference for helpful individuals. A 2007 study, for instance, saw researchers act out scenes with wooden dolls in front of six to ten-month-old infants. As one doll tried to climb a hill, another came and helped it. In another scenario, a third character prevented the doll from reaching the top of the hill. When given the chance to reach for the dolls, most of the babies opted for the helpful one.
Hoping to explore the origins of humans’ unusually cooperative behavior, Duke University researchers replicated this experiment with 24 bonobos at the Lola ya Bonobo sanctuary in the Democratic Republic of Congo, according to Nell Greenfieldboyce of NPR. In a study published in Current Biology, researchers say that they conducted four tests, two of which involved showing bonobos animations of different shapes with distinct, cartoonish eyes. (“Eyes were chosen since experiments have shown that apes are sensitive to eye contact and direction,” according to the study.)
First, the bonobos watched videos of a circle trying unsuccessfully to climb a steep hill. The circle encounters a triangle, which helps push him to the top. But in another version, a square comes along and pushes the circle back down the hill. Researchers then placed paper cutouts of a triangle and square on two apple slices, and offered them to the bonobos. Out of 13 bonobos that participated in this experiment, only two chose the triangle shape. The rest opted for the square—the “hinderer” character in the animations.
Another test involved three unfamiliar humans putting on a skit for the bonobos. One person played with a stuffed animal, laughing and tossing it in the air, before dropping it out of reach. Another actor then picked the toy up and tried to return it, but this helpful action was intercepted by a third actor, who grabbed the toy and put it in a bucket. The “helper” and “hinderer” then offered the bonobos a treat. And the primate audience consistently chose to take food from the bully.
Why did the bonobos show a preference for jerks? It is possible, researchers theorize, that they are simply attracted to dominant individuals. “Dominance is really important for apes because it determines access to resources, access to food and mating opportunities and things like that,” Christopher Krupenye, one of the authors of the study, tells Greenfieldboyce. “They're attracted to an individual who might be a powerful friend or ally, as opposed to someone who is just generally helpful or pleasant.”
Of course, “dominance” and “hindering” are not necessarily the same thing. As Khan puts it, “one could potentially be helpful and dominant, or antisocial and submissive.” The researchers note in their study that further investigations are needed to better understand the interplay between these two qualities. But it may very well be that a preference for cooperation and helpfulness played an important role in humans’ divergence from their primate cousins.