Bonobos Are Eager To Help Strangers Without Being Asked

While altruism is often practiced between close friends, people will also sometimes help random strangers they meet. New research shows that this social behavior is not unique to humans and is common amongst bonobos, another member of the great apes and one of humanity’s closest living relatives in terms of evolution.

Researchers from Duke University have done new research into altruism in bonobo communities. The researchers found that bonobos are willing to help other bonobos, even if they have not met these other bonobos before. This new revelation about the willingness of bonobos to assist strangers, in addition to friends and family, provides further support for the idea that bonobos are social animals that extend kindness towards others.

Helping Others At A Cost To Yourself

Previous studies have documented that bonobos engage in a wide array of social behavior. One study found that bonobos will console relatives or friends that are upset, in a display of behavior that could have its roots in empathy. Yet another study found that bonobos will share their food, even with total strangers, to get social interaction.

Brian Hare and Jingszhi Tan at Duke University were responsible for the study that investigated how bonobos share food, and their recent study followed up on those findings.  The Duke University team went to the Lola ya Bonobo sanctuary in the Democratic Republic of Congo to study how bonobos would interact with strangers when trying to obtain food that was out of reach.

“Bonobos Lana & Kesi 2006 CALVIN IMG 1301” by W. H. Calvin Ape Bonobo San Diego Zoo via Wikimedia Commons, CC-BY 4.0

The team suspended pieces of apples in bonobo enclosures with rope, and the ropes were held in place thanks to a wooden rod. Bonobos on the outside had a chance to remove the wooden rod and drop the piece of apple down to the stranger, who couldn’t reach the apple any other way. Crucially, this altruistic action was not without cost to the helper bonobos, as they started out across the enclosure where they were able to freely play with toys. They would have to cease playing with his toys and cross the enclosure, then climb up the cage to release the apple for a complete stranger.

The study found that bonobos were four times more likely to release the apple when there was a bonobo waiting in the cage below the apple, than when the cage was unoccupied.

The researchers also tried other variations of this setup, including a version where the mesh surrounding the cage had a hole in it. This hole allowed the bonobo in the cage to stick their arm through the mesh and gesture to the other bonobos for help. The study found that the helper bonobo would assist the other bonobo in obtaining food just as frequently, no matter if the cage bonobo requested help or not. This potentially means that bonobos are willing to assist others even when they’re complete strangers, when the strangers don’t ask for the assistance, and when there’s no immediate benefit to themselves.

Yawn Contagion

The research team also conducted a second phase of the experiment, which observed the phenomenon of yawn contagion in bonobos. This is when someone yawns and the person watching them also yawns. This phenomenon is thought to be linked with empathy in humans and is related to the functioning of mirror neurons. Mirror neurons are neurons that activate both when a person performs an action and when they observe the same action being performed by another person.

The researchers showed 21 bonobos a number of short videos. Some videos contained apes that had a neutral expression, while others were yawning. The research found that just as we yawn after seeing someone else yawn, so do bonobos. The yawns of strangers were at least as contagious as the yawns of group members, which according to the researchers, suggests that bonobos have a similar pro-social strength towards both strangers and group mates.

Tan hypothesizes that the affection for strangers bonobos exhibit could have evolved when the benefits of bonding began to outweigh the costs of bonding, like having to share food. Female bonobos will leave the group they are born in to join a new group of bonobos upon reaching adulthood, which means that they will have to establish bonds with strangers. In this sense bonobos, much like humans, could just be trying to make a good first impression.

“All relationships start between two strangers,” Tan says. “You meet a stranger, but you may meet them again, and this individual could become your future friend or ally. You want to be nice to someone who’s going to be important for you.”

Bonobos Vs. Chimpanzees

The research team noted that this is an experiment that would be difficult to reproduce with chimpanzees. Unlike bonobos, chimps are often more aggressive and more mistrustful of outsiders. Both chimps and bonobos share approximately 98% of their DNA with humans and with each other. However, bonobo and chimpanzee societies are structured differently.

Bonobos typically live in matriarchal communities that are fairly peaceful and communicate with complex vocal sounds. Bonobos are also known for the prominent role sex plays in social interactions. As discussed earlier, bonobos are more likely to comfort one another when they are stressed out. By contrast, chimpanzees are known for getting violent and aggressive when stressed. Furthermore, studies on chimpanzees seem to indicate that they are only more likely to help when specifically requested to do so and that they display yawn contagion only with members of their own group.

A Human Connection?

Tan is an anthropologist by training and spoke about the possible implications of the research, hoping it might shed some light on not only the behavior of primates but also the behavior of humans. Tan says that the evolution of human altruism is a puzzle and that there hasn’t been a great explanation for helping someone you don’t know at all, even though it happens fairly frequently.

While many hypothesize that it is culture or social norms that drive human altruism amongst strangers, the research on bonobos suggests humans could be biologically predisposed to altruistic action. Tan clarifies that a predisposition in this sense refers to a “tendency” to do something. It isn’t taught or learned and can be influenced by culture and experience, but it has its basis in our nature.

Tan says it is important to consider the role of biology if you want to promote peace, tolerance, and altruistic behavior.

Says Tan:

…If you don’t consider the role of biology, then the only tool you have [to encourage that behavior] is through culture and education. If we know that it’s part of our nature to do that, then how do you trigger this kind of predisposition to show up more often in real life? We don’t have to only use nurture as a tool; we can use nature as well. Combining the two of them would be even more powerful.