Discovering Us

Bonobos' Powerful Sisterhood

Episode Summary

Bonobos are close cousins of humans, known for their highly active sex lives and peaceful female-centered social structure. In this episode, Ashley Judd shares how researchers studying bonobos are unlocking the secrets of female friendship.

Episode Notes

Episode Transcription

Meredith Johnson:

This is Discovering Us from The Leakey Foundation and Signature Books … an audio companion to the book Discovering Us: 50 Great Discoveries in Human Origins. Written by Evan Hadingham and read for you by Ashley Judd.

I’m your host, Meredith Johnson.

The book Discovering Us explores 50 of the greatest discoveries in the ongoing quest to understand how our species evolved.

Those discoveries include famous fossil finds like Lucy - amazing advances in genetics - like the sequencing of the Neanderthal genome. And discoveries by iconic scientists like Jane Goodall.

This audio series highlights some great discoveries you might not have heard of. In this installment, you’ll learn how researchers studying bonobos are unlocking the secrets of female friendship. And how studying our great ape cousins helps us understand the roots of human behavior.

Here’s Ashley Judd…

Ashley Judd:

Bonobo’s Powerful Sisterhood

The first time primatologist Frans de Waal (frahnz deh wall) saw bonobos was in a Dutch zoo.

Then a student, de Waal was struck by how differently they looked and behaved compared to chimpanzees.

“Chimps are brawny bodybuilders,” he says, “whereas these apes looked rather intellectual. With their thin necks and piano-player hands, they seemed to belong in the library rather than the gym.”

Then he witnessed something strange. A male and female were squabbling over a cardboard box when they abruptly stopped fighting and began mating.

At first he dismissed it as an anomaly. It was only when de Waal began intensive videotaping of bonobos at the San Diego Zoo that he realized how sex permeates every aspect of their social life.

The more you watch bonobos, de Waal says, “the more sex begins to look like checking your email, blowing your nose, or saying hello. A routine activity.”

The zoo studies carried out by de Waal and his colleague Amy Parish showed how constant sex helps defuse rivalries, aggressive behavior, and competition over food among bonobos.

In fact, sexual activity between females is a crucial key to bonobo society - which has a unique female-dominated social structure.

Understanding the riddle of bonobo female power has attracted a fresh generation of researchers who are gradually unlocking its secrets.

Among them is Leakey Foundation grantee Liza Moscovice (LIE-za MOSS-co-vice). Since 2011, she has been based at the LuiKotale (louie-CA-tall) site in the Congo, reached by a two-hour flight, a 15-mile jungle hike, and a dugout crossing of the Lokoro (lo-core-oh) river.

Here, people from local communities collaborate with international researchers to monitor and protect several bonobo groups.

Moscovice’s work at LuiKotale shows that female solidarity is the most striking feature of bonobo society. Like chimps, male bonobos remain in their birth community and females migrate to join other groups when they reach adolescence.

But chimp bands are ruled by dominant males who bond together in strong coalitions while, at LuiKotale, male bonobos remain attached to their mothers.

It is the females who form a wide range of strong friendships and alliances within the groups they migrate to, even though they are not genetically related.

Moscovice says (that), “Females prefer to cooperate with other unrelated females and we don’t quite know why yet.”

“Sometimes, they’ll even cooperate at the expense of their kin. They’ll avoid helping their adult sons if it will cause conflicts with their female friends. This is exceptional among primates—basically, putting friends above your own family.”

This “secondary sisterhood,” as de Waal calls it, is the strongest force in the bonobo world. Females hold the top social position and cement their same-sex alliances with constant sexual activity.

This physical contact seems to be how females signal trust as they form temporary alliances to deal with conflicts that erupt within the group.

Moscovice notes, “It’s not that the high-ranking females cooperate against the low-ranking females. It’s more common that low-ranking females get help from high-ranking females against males that they’re in conflict with.”

Belligerent or bothersome males are put in their place in no uncertain manner.

In one case observed at Wamba (wahm-bah), four males focused unwanted sexual attention on a low-ranking female, triggering sudden retaliation from three high-ranking females, who piled onto one of the offenders, biting and screaming.

Primatologist Nahoko Tokuyama (na-HO-ko TOE-coo-yah-mah), who witnessed the attack said, “he dropped from the tree and ran away, and he didn’t appear again for about three weeks. Being hated by females is a big matter for male bonobos.”

Remarkably, female social networks can extend beyond their own local group to other bonobo communities. Unlike the violence that often flares up between highly territorial chimps, bonobo communities occasionally coalesce and mingle, with generally peaceable results. In her last field season, Moscovice observed a fusing of two groups, totaling close to 80 individuals, that lasted a month and a half.

Moscovice said they weren’t always together. They were splitting up and coming together again just like a regular bonobo community. She said there was sharing of fruit trees but also some serious aggression, so it wasn’t all peaceful. But there was a lot of tolerance, especially among the females.

During this extended visit, unrelated females from the two groups would express their long-term friendships by sexual activity, grooming, and feeding together.

One of Moscovice’s main goals is to understand how these female friendships work and the benefits they bring. In urine samples collected before and after sexual activity within communities, she has discovered high levels of oxytocin (OX-ih-toe-sin)—a hormone well-known in the human world for encouraging feelings of trust and empathy in social encounters.

In much-publicized human experiments, a mere whiff of oxytocin, delivered to the brain via a nasal spray, was usually enough to make participants more trusting of strangers.

Although the effect in humans has now proven to be weaker than once assumed, the high oxytocin levels detected in female bonobos after physical contact may partly explain what motivates them to cooperate with so many female partners.

Moscovice’s research suggests the role of oxytocin is only part of the story.

The powerful sisterhood of female bonobos, in stark contrast to the male-dominated chimpanzee realm, raises intriguing questions about the origins of their unique social world and our own.

[MUSIC rises and then ducks under closing credits]

Meredith Johnson:

Discovering Us: 50 Great Discoveries in Human Origins was written for The Leakey Foundation by Evan Hadingham. It was published by Signature Books. The stories are read for you by Ashley Judd.

All the episodes of this audio companion are available to listen to right now! Make sure to subscribe and share this series with a friend.

You can buy a copy of Discovering Us at your local bookstore or wherever you buy books. There’s a link in the show notes.

The Leakey Foundation is a nonprofit organization dedicated to funding human origins research and sharing discoveries. The science you heard about today was made possible by Leakey Foundation supporters. Visit our website to learn how you can get involved. Go to leakeyfoundation.org. That’s l-e-a-k-e-y foundation dot org.