found common in chimpanzees. No doubt this was reductive and I had a lot to learn, but I saw in the gaze of the bonobo evidence of a deeply social being that, if it could speak, might have a number of questions for me.
Other photographs showed bonobos in a variety of familiar postures: lounging on their backs, one leg crossed over the other; or mating in the missionary position, muscles taut in their arms, the male grinning as if life couldn’t be better; or a mother standing, staring off, holding sugarcane, head poised on a stretched neck. With their long, slender limbs, they appeared so humanlike that, just to get a sense of proportion, I had to look up their weight: one hundred pounds for males—a little less than chimpanzees—and seventy for females. It was difficult to imagine such a close relative being hunted for the bushmeat trade, thousands slaughtered during the two Congo wars between 1996 and 2003, possibly as few as five thousand remaining.
Both because of their highly sexual nature and because one has never been witnessed killing another of its own kind, bonobos have recently become the stars of the great ape world. Even orangutan males, when battling over females, occasionally deliver fatal wounds, as do silverback gorillas. Gorillas sometimes kill infants, and for chimpanzees this can be a matter of course. Dominant chimpanzee mothers do away with the children of others, and males wage all-out wars, then slaughter the infants and take the females for their own, a description that reads like any of a million lines out of human history.
Bonobo society, however, is matriarchal. Females forge the alliances, and a male’s rank depends on that of his mother. When groups meet, males hoot but stand back while females cross over to one another in what may end up resembling an orgy. As for infanticide, it has never been witnessed; all bonobos in the group care for the welfare of their young. They have been nicknamed the “hippies of the forest” and the “Left Bank ape,” owing to where they live in relation to the Congo River. Unlike other great apes, they use a variety of sexual positions and often mate face-to-face, gazing into each other’s eyes. They enjoy oral sex and French kissing, and they make love for pleasure, comfort, or closeness, as a means of greeting, or just because they love each other. Sex is their hug, their handshake, their massage, and their noon martini. Sometimes, it allows them to defuse social tension, minimize violence, and resolve conflicts over resources, the females rubbing one another’s clitorises and the males penis-fencing—hardly solutions our leaders would try.
Whereas gorillas, chimpanzees, and orangutans have clear places in the popular imagination, bonobos are latecomers. Their resemblance to chimps and their home far from the coast, within one of the Congo’s most daunting landscapes, have prolonged our ignorance. Chimpanzees first appeared in Western literature in the sixteenth century, orangutans in the seventeenth, and the gorilla’s name dates back to a Carthaginian who, in 500 BC, traveled Africa’s West Coast and returned with the skins of “wild men” that the locals called gorillae. Though records since the 1880s show apes at the heart of the Congo basin, bonobos were not recognized as a distinct species until the twentieth century. Yale primatologist Robert Yerkes owned a bonobo named Prince Chim in the mid-1920s but thought he was a chimpanzee, albeit an extraordinary one. He wrote: “In all my experience as a student of animal behavior I have never met an animal the equal of Prince Chim in approach to physical perfection, alertness, adaptability, and agreeableness of disposition. . . . Doubtless there are geniuses even among the anthro-poid apes.”
Bonobos were not identified as distinct from chimpanzees until the late 1920s. Harvard zoologist Harold J. Coolidge Jr. wrote that he visited Tervuren, Belgium, in 1928, after a long university expedition to collect gorilla specimens in the Belgian Congo. “I shall never forget, late one afternoon in Tervuren, casually picking up from a storage tray what clearly looked like a juvenile chimp’s skull from south of the Congo and finding, to my amazement, that the epiphyses were totally fused.” This meant that, despite its size, the skull was that of an adult. He found four more similar skulls among those of the chimpanzees and planned to write a scientific paper on the subject, describing a new type of chimpanzee. However, two weeks later, the German anatomist Ernst Schwarz visited, and Henri Schouteden, the director of Tervuren’s Royal Museum for Central Africa, showed him the skulls that had interested Coolidge. “In a flash Schwarz grabbed a pencil and paper, measured one small skull, wrote up a brief description, and named a new pygmy chimpanzee race: Pan satyrus paniscus,” recalled Coolidge. “He asked Schouteden to have his brief account printed without delay in the Revue Zoologique of the Congo Museum. I had been taxonomically scooped.” But reasonably enough, Schwarz had his own account: he’d been studying primates, he wrote, and had come to Tervuren specifically to examine the skulls, a recent shipment from the Congo.
Despite not receiving credit for being the first to identify the bonobo, in 1933 Coolidge published the paper that would establish it not as a subspecies of the chimpanzee, Pan troglodytes, but as a separate species, Pan paniscus. Having remarked the similarities in the torso-to-limb proportions of bonobos and humans, he wrote that the species, still known as the pygmy chimpanzee despite being marginally smaller than most chimpanzees, “may approach more closely to the common ancestor of chimpanzees and man than does any living chimpanzee hitherto discovered and described.”
In 1954, German scientists Eduard Tratz and Heinz Heck proposed that, because of its marked differences from the chimpanzee, the pygmy chimpanzee should be classified under a different genus. They suggested Bonobo paniscus, as they believed bonobo to be the Congolese name for the species. Though the word bonobo wasn’t found historically among the Bantu dialects, it may have been a misspelling on a crate shipped from Bolobo, a town on the Congo River from which bonobos were sent.
While Tratz and Heck’s classification has been generally accepted by the scientific community, some argue that bonobos and chimpanzees are so close to humans that they should be classified in the Homo genus. Even Carl Linnaeus, who in the eighteenth century developed the system of Latin names that botanists and zoologists still use, called the orangutan Homo nocturnus or Homo sylvestris orang-outang, though he based his evaluation on the reports of travelers who claimed that the Indonesian great ape could speak.
Until recently, bonobos lacked public champions whereas the other great apes have had Jane Goodall, Dian Fossey, and Birutė Galdikas. But with a growing number of books, documentaries, and films now dedicated to them, bonobos are becoming media darlings even as they are being exterminated in the Congo. The attention they receive can be attributed to their peaceful disposition and their reputation as Kama Sutra apes—a reputation that is, of course, based on behavior seen through the lens of human sexuality.
The primatologist Frans de Waal writes in Bonobo: The Forgotten Ape of how bonobos use sex for both appeasement and affection, saying that the label sex might be inappropriate if perceived as a “behavioral category aimed at an orgasmic climax.” A little later in his career, though, in response to an article questioning the sexual nature of bonobo behavior, he writes, “Fortunately, a United States court settled this monumental issue in the Paula Jones case against President Bill Clinton. It clarified that the term ‘sex’ includes any deliberate contact with the genitalia, anus, groin, breast, inner thigh, or buttocks.” With bonobos, sex encompasses a number of tendencies—something, de Waal points out, that is also true for humans, though rarely acknowledged: “Our sexual urges are subject to such powerful moral constraints that it may have become hard to recognize how—as Sigmund Freud was the first to point out—they permeate all aspects of social life.” De Waal suggests that bonobo society could teach us much about what human sexuality might look like without those constraints.
As I began to gain a better understanding of bonobos, of what traits they share with humans and how they might experience the world, I encountered the work of Dr. Sue Savage-Rumbaugh, an American primatologist. Since the 1970s, Savage-Rumbaugh has been working with great apes in captivity, investigating whether they have a capacity for language. She first studied chimpanzees at Georgia State University, then bonobos that had been brought from the Congo. She developed technology that enabled bonobos to communicate with humans by pushing a lexigram on a keyboard attached to a computer, which would log and articulate its corresponding word in English. The approach Savage-Rumbaugh developed wasn’t clinical but holistic; she used the lexigrams in conjunction with activities that gave them immediate, relevant, even urgent