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Bonobos Offer Clues To Why Humans Evolved To Value Niceness

AILSA CHANG, HOST:

Humans evolved to be nice. Well, at least some of the time. It's a trait that has helped us succeed as a species. Now scientists are trying to understand how niceness evolved. Just before the pandemic, NPR's Jon Hamilton visited the Democratic Republic of the Congo, and he reports now on what researchers are learning from some peace-loving apes there.

JON HAMILTON, BYLINE: A few miles outside of Kinshasa, along the banks of the Lukaya River, is a sanctuary for bonobo. It's called Lola ya Bonobo, and about 60 of the animals live here. They look like smallish chimpanzees, and they spend most of their day in the forest...

(SOUNDBITE OF BONOBOS SCREECHING)

HAMILTON: ...Until it's time to eat. Bernard Nsangu is a caretaker here at Lola ya Bonobo, which means bonobo paradise.

BERNARD NSANGU: (Non-English language spoken).

HAMILTON: He says the bonobos understand just about everything he says in French or Lingala. And right now, they're passing along the news that pineapple is coming. Soon, more than a dozen bonobos have assembled near the edge of their enclosure.

(SOUNDBITE OF BONOBOS SCREECHING)

HAMILTON: With chimps and many other species, food can lead to aggression. But Suzy Kwetuenda, a biologist at Lola, says bonobos take a different approach.

SUZY KWETUENDA: You see, there is many, many action of sex, many negotiation around, that make peace.

HAMILTON: Bonobos, along with chimps, are our closest living relatives. And you can see aspects of our own behavior in both species. Chimps tend to rely on cunning and competition. Bonobos emphasize cooperation and sharing. Dr. Jonas Mukamba, the head veterinarian here, says bonobos also have an unusual approach to leadership.

JONAS MUKAMBA: (Non-English language spoken).

HAMILTON: "Here in the bonobos' home," he says, "it is the females who dominate, and it is a female who is chief of the group." Suzy Kwetuenda says that's one reason the meal we're watching is so peaceful. She points to an alpha female.

KWETUENDA: This is Samandua - big mom, tough mom. And as you can see, she's in the front. She has to show that she's very concerned by all organization in the group.

(SOUNDBITE OF BONOBO SCREECHING)

HAMILTON: Bonobos are unusual in their willingness to share, something that was documented in a series of experiments here at Lola. The research was done by Brian Hare of Duke University and Suzy Kwetuenda.

KWETUENDA: So I want to show you. So this is normally the lab. As you see, it's very large, and we have many rooms.

HAMILTON: Kwetuenda says in one experiment, they put two bonobos in adjacent rooms. Then they gave one of the animals some really special food.

KWETUENDA: It must be the favorite food, like apples. They love bananas. And most of times, we were normally trying to put bonobo sauce - I remember it was the milk, cream.

HAMILTON: The bonobo with food could choose to eat alone or use a key to let in their neighbor.

KWETUENDA: In our mind, we thought that because of nice food, they would first eat, but we are surprised to see that roommate is more important than food - than favorite food.

HAMILTON: The scientists repeated the experiment with three bonobos, one of whom was a stranger.

KWETUENDA: We also found that bonobos share with anyone, but they prefer to share with a stranger than a roommate.

HAMILTON: And in yet another experiment, scientists showed that bonobos are willing to help one another obtain food, even if they know they won't get to share it. This sort of behavior may seem odd from an evolutionary perspective, but there's evidence that large-scale cooperation is what helped Homo sapiens outlast other early humans. And it's allowed our species to share new ideas, create vast nations and explore other planets.

(SOUNDBITE OF CRICKETS CHIRPING)

HAMILTON: Scientists have published more than 75 studies from research done at Lola ya Bonobo. The DRC is the only place on Earth where these animals still live in the wild, and this sanctuary provides a place to study their behavior in a naturalistic setting. Claudine Andre, who founded the sanctuary nearly 30 years ago, says the scientific studies have documented what she sees every day - sharing, cooperation and empathy.

CLAUDINE ANDRE: They are full of empathy, this animal, and full of love also. And all their life is based on relation between the other one.

HAMILTON: A sampling of bonobo science suggests Andre is right. Studies show that if one bonobo yawns, others will yawn too - a behavior closely associated with empathy. They also show that bonobos understand when someone is trying to help them. If a scientist hides a treat under one of two upside down cups, bonobos will look to the scientists for a gesture indicating which cup to choose. Chimps, for all their cleverness, just keep choosing a cup at random. Andre says bonobos also communicate through eye contact much the way people do.

ANDRE: If you look to a chimpanzee, every three seconds, it turns its eyes. A bonobo - he wants to know, who are you? What is the connection we can have?

HAMILTON: Studies even show that bonobo brains include special circuits for social interaction that are not found in chimpanzees. The result is an animal predisposed to sharing, tolerance, negotiation and cooperation. Andre says those are all traits she sees in humans on a good day.

ANDRE: Human can be a fantastic bonobo with a big heart, help people and so, or very dangerous warriors. We are mixed.

HAMILTON: It's been about 6 million years since the death of our last common ancestor with chimps and bonobos. Since then, we humans have channeled our inner bonobo to share and cooperate on a massive scale. But we've acted more like chimps when it comes to behaviors like violence against members of our own species. Humans do not consider every stranger a potential friend. Studies show we may not even consider a stranger fully human if they belong to a group perceived as other and threatening. Scientists say when that happens, we tend to suppress empathy and embrace cruelty.

(SOUNDBITE OF BONOBO SCREECHING)

HAMILTON: Yvonne Vela Tona, better known as Mama Yvonne, sits on the steps of a terrace overlooking the Lukaya River. An orphaned bonobo infant named Esake is climbing on her head and shoulders, looking for snacks and occasionally trying to grab the microphone I'm holding.

(SOUNDBITE OF BONOBOS SCREECHING)

HAMILTON: Mama Yvonne has been a mother to a couple of human children and surrogate mother to more than 20 bonobos. And like Claudine Andre, she's seen both the chimp and bonobo sides of human behavior. Mama Yvonne left Angola more than 20 years ago to escape a civil war that left 500,000 people dead. Since then, she's lived in a nation where armed conflicts have killed millions. She says her time at Lola ya Bonobo has made her think about her own species.

YVONNE VELA TONA: (Non-English language spoken).

HAMILTON: "What people can learn from bonobos," she says, "is that war and violence are not inevitable. We have within us the capacity to resolve conflicts through other means."

Jon Hamilton, NPR News.

(SOUNDBITE OF BONOBO'S "CIRRUS") Transcript provided by NPR, Copyright NPR.