The Bonobo:
"Newest" apes are teaching us about ourselves

By Anthony DeBartolo

MILWAUKEE - Thirty years ago, they weren't even mentioned in textbooks on human evolution.

Today, researchers say, the bonobo (pronounced bow-NO-bow), the last of the great apes discovered by Western science, is starting to rewrite those textbooks, along with many of our basic assumptions about human nature.

"The bonobo shows the flexibility in our lineage that we didn't know we had before," says Frans de Waal, a prominent investigator at the Yerkes Regional Primate Research Center in Atlanta and professor of psychology at that city's Emory University. "They're female-centered, egalitarian, have no cooperative hunting and substitute sex for aggression."

After 20 more years of research, predicts De Waal, the bonobo "is going to change the whole picture of human evolution."

Right now, though, Barbara Bell is more interested in getting them to behave. As a keeper/trainer for the Milwaukee County Zoo, she works daily with the largest group of bonobos (5 males and 4 females, ranging in age from 3 to 48 years) in North America, making it the second largest collection in the world (the largest can be found at the Dierenpark Planckendael, in Mechelen, Belgium). There are only 120 captive worldwide.

"It's like being with nine 2 1/2 year olds all day," she says. "They're extremely intelligent."

Before she initiated a positive-reward training program with the bonobos three years ago -- the approach many zoos use to train sea lions -- "there was no trust between us," Bell says. The apes would often scream loudly in their distinct, high-pitched voices, or try, usually with great success, to urinate on strangers visiting their holding pens in the basement of the zoo's Family of Apes of Africa Pavilion (Visitors in the public viewing area upstairs, by the way, are protected by glass).

"We had some very bad behavior to contend with," says Bell.

Teaching them to respond to command words, to willingly move from holding pen to holding pen, and present parts of their bodies for examination, has resulted in less stress for bonobo and trainer alike, Bell notes.

Before training, examining any bonobo anatomy, usually required full anesthesia. Now, Bell can often do it with a simple request and a grape.

"They understand a couple of hundred words," she says. "They listen very attentively. And they'll often eavesdrop. If I'm discussing with the staff  which bonobos (to) separate into smaller groups, if they like the plan, they'll line up in the order they just heard discussed. If they don't like the plan, they'll just line up the way they want."

"They also love to tease me a lot," she says. "Like during training, if I were to ask for their left foot, they'll give me their right, and laugh and laugh and laugh. But what really blows me away is their ability to understand a situation entirely."

For example, Kitty, the eldest female, is completely blind and hard of hearing. Sometimes she gets lost and confused.

"They'll just pick her up and take her to where she needs to go," says Bell. "That's pretty amazing. Adults demonstrate tremendous compassion for each other."

The bonobo's apparent ability to empathize, in contrast with the more hostile and aggressive bearing of the related chimpanzee, has some social scientists re-thinking our behavioral heritage -- especially the dominant male/submissive female scenario.

"The current model of our progress as a species uses the chimpanzee as the touchstone of human evolution. Male dominance, aggression, cooperative hunting, warfare are all a part of the story," says De Waal.

But as he wrote in his 1997 book, "Bonobo: The Forgotten Ape": "Bonobo society seems ruled by the 'Make Love, Not War' slogan of the 1960s, rather than the myth of a bloodthirsty killer ape that has dominated (evolutionary) textbooks for at least three decades."

One reason we know so little about the bonobo today is that no one even knew the creature existed until 1929, when its skull was discovered in a Belgian museum. Another reason for our ignorance is the animal's isolation. Its sole known habitat is the remote tropical rain forests of the Democratic Republic of Congo (formerly Zaire) in central Africa.

At first assumed to be a slightly smaller sub-species of chimpanzee, the bonobo was originally called a pygmy chimp. A few years after the Belgian discovery, however, the bonobo was accorded its place as a distinct species alongside the other great apes: gorilla, chimpanzee and orangutan.

The earliest study comparing bonobos and chimpanzees was carried out in the 1930s at Germany's Hellabrunn Zoo in Munich. The three bonobos used in the study, incidentally, were so terrified by Allied bombardment of the city during the war, they died of heart failure.

Among the differences noted: The more vocal bonobos are sensitive, lively and nervous, while chimps are coarse and hot-tempered; bonobos defend themselves by kicking with their feet, while chimps pull attackers close and bite; a bonobo's voice contains "a" and "e" vowels, but chimps use more "u" and "o" vowels; and although physical violence is rare among bonobos, with chimps it's common.

Not much else was known about bonobos until the 1970s, when Japanese researchers became the first to venture into their African habitat.

The ape's isolation, combined with longstanding despotism and political strife in the Democratic Republic of Congo, deforestation and the killing of bonobos for food has not only limited subsequent field work but has jeopardized the animals' survival.

Gay Reinartz, coordinator of the Bonobo Species Survival Plan for the Zoological Society of Milwaukee County, remains hopeful, yet is deeply concerned. "We're on the edge," she says. "It could go either way."

In an effort to tip the scales, Reinartz is trying to raise $220,000 for a planned survey of the Congo's Salonga National Park to determine the bonobos' distribution and conservation status. Researchers have estimated the total bonobo population at 5,000 to 20,000.

"What we do in this country will make a difference whether or not these guys live," Reinartz says. "I'm not saying I have all the answers, because it's a complex problem. But what we do in terms of foreign policy, conservation and stimulating public demand, will affect this species making it."

For Reinartz, bonobos deserve to make it "because they have their own special merits that have nothing to do with the fact that we're related."

It's the animal's relationship to humans, though, that's causing all the interest.

Consider: The bonobo and chimp are equally close to us DNA-wise. Each shares more than 98 percent of our genetic material. As De Wall puts it: "That's about as close as a fox is to a dog."

The bonobos' body proportions, however, compare more favorably than any other living ape to the 3.2 million-year-old skeletal remains of Australopithecus afarensis, that transitional creature between ape and man that anthropologists named Lucy.

While resembling a chimp, the bonobo's body "immediately strikes us as more gracile and elegant," says De Waal. "The body is more slim and slender, the head is small and sits on a thin neck and narrow shoulders."  Consequently, he says, when you see a bonobo stand or walk upright, you can't help but feel you've been there.

About 6 million years ago, the human lineage split off from the rest of the primate family tree. Three million years ago, the bonobo went its separate way. The chimp, you could say, is still riding our common evolutionary tree trunk today.

Because researchers believe the bonobo may never have left its ancestral rain forest, they reason that it may have changed less during its evolution than the chimpanzee, which is thought to have physically adapted as its environment changed. Of the bonobo, chimpanzee and man, "the bonobo may more closely resemble the common ancestor of all three modern species," De Waal says. "It's an important issue that's yet to be resolved."

Since De Waal's book was published, the issue that seems to have gotten the most attention is the animal's overt sexuality. It's hard to ignore.

Zoo observations suggest, on the average, that every male, female and child bonobo engages in some form of heterosexual, homosexual or self-sexual activity every 1 1/2 hours. Adult rape, or any sexual abuse of an infant, however, has never been recorded in captivity or the wild.

"From what I've read in the popular press, it's gotten a little blown up," Bell says protectively. "You'd think they do it every 10 minutes."

But it's not the frequency that seems to startle people, Bell says; it's the too-human-for-comfort mode of the behavior.

For example, the frontal orientation of the bonobo's genitalia makes it one of only a handful of animals able to copulate face-to-face. And, as with humans, sex is usually engaged in for reasons other than procreation.

For bonobos, sex means everything from "hello" to "How about dinner?" De Waal calls it their "social balm."

When females embrace -- which is often in this female-controlled community -- "it's called a GG rub," says Bell. "Genital-to-genital stimulation. It's like, 'Hello, how are you? I haven't seen you in a while.' "

The public, however, usually doesn't get it. "We get some pretty grossed-out parents," Bell says.

And the bonobos -- especially the males -- seem to enjoy grossing them out. "They like to put their butts up to the glass because it gets such a great reaction."

"When Lomako, a 13-year-old male, is in rare form, he masturbates. Usually it's when he sees uniforms, when there are 30 Brownies or Girl Scouts out front," says Bell with a sigh. "He doesn't know it's taboo; he just gets a reaction."


This article first appeared in the  Chicago Tribune on June 11, 1998.

© 1998 Hyde Park Media