The trackers and I retreat for half an hour through the jungle. I crawl into a one-man tent, while the trackers sleep in the open around a fire they keep going all night to ward off leopards. At 5 a.m., I crouch with the trackers beneath the trees as the bonobos wake, stretch and eat leaves and fruits growing next to their nests—breakfast in bed, bonobo-style. A female swings to the next tree and rubs genitals with another female for about a minute, squeaking, while a male and a female, balanced on a bough, mate face to face, her legs wrapped around his waist. An hour later the troop swings off into the jungle. No one knows exactly why bonobos have sex so often. One leading explanation is that it maintains bonds within the community; another is that it prevents males from knowing which infants they sired and thus encourages them to protect all of the young in a group. Bonobo males are affectionate and attentive to infants; chimpanzee males, in contrast, are known to kill the offspring of rival males.
Back at camp, I meet with two Congolese researchers from the Ministry of Scientific Research and Technology. They had ridden bikes 35 miles along a jungle path from the village of Wamba. One of them, Mola Ihomi, spends the year at Wamba collecting bonobo data to share with researchers from Kyoto University, the same institution at which Kano worked years ago. The bonobo groups studied so far usually range in size from 25 to 75 members. The animals have what primatologists call a fission-fusion social structure, in which the group gathers together at night to sleep but splits into smaller parties during the day to forage. The groups include males and females, adults and young.
Bonobo researchers no longer lure their subjects with sugar cane. In fact, Ihomi says, some scientists point out that Kano observed bonobos in an unnatural situation. Normally, bonobos eat leaves and fruit, and there's plenty to go around. But enticed into the sugar cane field, the animals were out of their treetop habitat and competing for a concentrated resource. By watching bonobos in more natural settings, Ihomi and others have discovered that females are not necessarily as dominant as they appeared in the sugar cane field. "The alpha male is usually in charge," Ihomi says. The alpha male determines where the troop eats and sleeps and when it moves, and he is the first to defend the troop from leopards and pythons. But bonobo society is still much less authoritarian than that of other great apes. "If the alpha female doesn't want to follow him, she sits there and then the rest of the troop follows her lead and don't move," Ihomi says. "She always has the last say. It's like the alpha male is the general and the alpha female is the queen."
Researchers also now believe that the bonobo creed of making love, not war, is not as absolute as earlier studies suggested. Near Wamba, Ihomi says, he and his colleagues tracked three bonobo groups, two of which engaged in rambunctious sex when they ran into each other. But when the groups ran into the third group, "which isn't often," he says, "they display fiercely to defend their territory, males and females screaming, throwing dung and sticks at each other. They even fight, sometimes inflicting serious bite wounds."
Primatologists still regard bonobos as peaceful, at least compared with chimpanzees and other great apes, which are known to fight to the death over females or territory. Ihomi says, "I have never seen a bonobo kill another bonobo."
The effort to save wild bonobos is hampered by a lack of basic information. One urgent chore is to determine how many of the animals are left in the wild. By all estimates, their numbers are well down since the 1970s. "Political instability, the threat of renewed civil war, a surging human population, the thriving bush-meat trade and the destruction of bonobo habitat in the DRC is hurrying them toward extinction in the wild," says Daniel Malonza, a spokesman for The Great Apes Survival Project, a United Nations body set up five years ago to arrest the dramatic decline of the great apes.
In Mbandaka, Jean Marie Benishay, BCI's national director, showed me a photograph of bonobo skulls and bones that had been on sale at a village market for use in rituals. The seller told him the six bonobos had come from an area near Salonga National Park, southwest of Kokolopori, where they were once common but are rarely sighted these days. Gruesome as the photograph was, Benishay looks encouraged. "They come from a place where we thought bonobos had disappeared," he said with a grim smile. "This proves bonobos are still out there."
In the past two years, Paul Raffaele has reported for the magazine from Uganda, the Central African Republic, Zimbabwe, Cameroon, Niger, Australia, Vanuatu and New Guinea.