The Bonobo (Pan paniscus), until recently usually called the Pygmy Chimpanzee (and less often the Dwarf or Gracile Chimpanzee), is one of the two species making up the chimpanzee genus, Pan. The other species in genus Pan is Pan troglodytes, or the Common Chimpanzee. Although the name "chimpanzee" is sometimes used to refer to both species together, it is usually understood as referring to the Common Chimpanzee. The Bonobo is endangered, and is found in the wild only in the Democratic Republic of Congo. Along with the Common Chimpanzee, the Bonobo is the closest relative to Humans. Since neither species are proficient swimmers, it is possible that the formation of the Congo River 1.5–2 million years ago lead to the speciation of the Bonobo, which live south of the river, from the ancestors of the Common Chimpanzee, which live north of the river.
German anatomist Ernst Schwarz is credited with having discovered the Bonobo in 1928, based on his analysis of a skull in the Tervuren museum in Belgium that had been thought to have belonged to a juvenile chimpanzee. Schwarz published his findings in 1929. In 1933, American anatomist Harold Coolidge offered a more detailed description of the Bonobo, and elevated it to species status. The species is distinguished by relatively long legs, parted hair on their head, a matriarchal culture, and the prominent role of sexual activity in its society.
But there is still controversy. Scientists such as Morris Goodman of Wayne State University in Detroit argue that the Bonobo and Common Chimpanzee are so closely related to humans, their genus name should also be classified with the Human genus Homo: Homo paniscus, Homo sylvestris, or Homo arboreus. An alternative philosophy suggests that the term Homo sapiens is actually the misnomer, and that humanity should be reclassified as Pan sapiens. In either case, a name change of the genus is problematic because it complicates the taxonomy of other species closely related to humans, including Australopithecus.
Recent DNA evidence suggests the Bonobo and Common Chimpanzee species effectively separated from each other less than one million years ago. The chimpanzee line split from the last common ancestor with the Human approximately four to six million years ago. Because no species other than Homo sapiens has survived from the human line of that branching, both Pan species are the closest living relatives of humans, and cladistically exactly equally close to humans.
The Bonobo is more gracile (slight in form) than the Common Chimpanzee. Its head is smaller than that of the Common Chimpanzee with less prominent eyebrow ridges. It has a black face with pink lips, small ears, wide nostrils, and long hair on its head. Females have slightly more prominent breasts in contrast to the flat breasts of other female apes, though not as prominent as those of humans. The Bonobo also has a slim upper body, narrow shoulders, thin neck, and long legs compared with the Common Chimpanzee. The Bonobo walks upright about 25% of the time during ground locomotion. These characteristics, and its posture, gives the Bonobo a more human-like appearance than that of the Common Chimpanzee (see: bipedal Bonobos). Moreover, the Bonobo has highly individuated facial features, as humans do, so that one individual can look significantly different from another, adapted for visual recognition in social interaction.
Recent observations in the wild indicate that the males among the Common Chimpanzee communities are extraordinarily hostile to males from outside of the community. Parties of males 'patrol' for the unfortunate neighbouring males who might be traveling alone, and attack those single males, often killing them. (Some researchers have suggested, however, that this behaviour has been caused by a combination of human contact and interference and massive environmental stress caused by deforestation and a corresponding range reduction.) This does not appear to be the behavior of the Bonobo males or females, both of which seem to prefer sexual contact over violent confrontation with outsiders. The Bonobo lives in different areas from the more aggressive Common Chimpanzee. Neither of the species swims, and they sometimes inhabit ranges on opposite sides of the great Congo River. It has been hypothesized that Bonobos are able to live a more peaceful lifestyle in part because of an abundance of nutritious vegetation in their natural habitat, allowing them to travel and forage in large parties.
The popular image of the Bonobo as a "peaceful ape" has come under fire. Accounts exist of Bonobos in zoos mutilating one another and engaging in bullying. These incidents may be due to the practice in zoos of separating mothers and sons. Bonobo society is dominated by females, and severing the lifelong alliance between mothers and their male offspring may make them vulnerable to female aggression. De Waal has warned of the danger of romanticizing Bonobos: "All animals are competitive by nature and cooperative only under specific circumstances" as well as writing that "When first writing about their behavior, I spoke of 'sex for peace' precisely because bonobos had plenty of conflicts. There would obviously be no need for peacemaking if they lived in perfect harmony". In marked contrast to the Common Chimpanzee there are no confirmed reports of lethal aggression between Bonobos, either in the wild or in captivity. The immature state of Bonobo research in the wild compared to that of the Common Chimpanzee, however, means that lethal aggression may yet be discovered.
Sexual activity happens within the immediate family as well as outside it, and often involves adults and children, even infants. Bonobos do not form permanent relationships with individual partners. They also do not seem to discriminate in their sexual behavior by gender or age, with the possible exception of sexual intercourse between mothers and their adult sons; some observers believe these pairings are taboo. When Bonobos come upon a new food source or feeding ground, the increased excitement will usually lead to communal sexual activity, presumably decreasing tension and allowing for peaceful feeding.
Bonobo males frequently engage in various forms of male-male genital sex (frot). One form has two males hang from a tree limb face-to-face while "penis fencing". Frot may also occur where two males rub their penises together while in missionary position. A special form of frot called "rump rubbing" occurs to express reconciliation between two males after a conflict, where they stand back-to-back and rub their scrotal sacs together.
Bonobo females also engage in female-female genital sex (tribadism) to socially bond with each other, thus forming a female nucleus of Bonobo society. The bonding between females allows them to dominate Bonobo society - although male Bonobos are individually stronger, they cannot stand alone against a united group of females. Adolescent females often leave their native community to join another community. Sexual bonding with other females establishes the new females as members of the group. This migration mixes the Bonobo gene pools, providing genetic diversity.
Bonobo reproductive rates are not any higher than that of the Common Chimpanzee. Female Bonobos carry and nurse their young for five years and can give birth every five to six years. Compared with Common Chimpanzees, Bonobo females resume the genital swelling cycle much sooner after giving birth, allowing them to rejoin the sexual activities of their society. Also, Bonobo females who are either sterile or too young to reproduce still engage in sexual activity.
Craig Stanford, an American primatologist, has challenged the claim that Bonobos are more sexually active than Common Chimpanzees. Stanford compared existing data on Common Chimpanzees and Bonobos in the natural habitat and found that female Common Chimpanzees copulated at least as often as female Bonobos, while male chimpanzees actually copulated more than male Bonobos. His comparison excluded same-sex sexual contacts, however, which are very common in Bonobos. De Waal's book on Bonobos includes interviews with field workers and relies on the studies by Takayoshi Kano, the only scientist to have worked for two decades with wild Bonobos. New studies in Africa by Gottfried Hohmann, a research associate at the Max Planck Institute for Evolutionary Anthropology of Leipzig, Germany, believes to have seen significant violence, but fact remains that there are thus far no documented cases of lethal aggression among Bonobos, in sharp contrast to the evidence for Common Chimpanzees.
Bonobo party size tends to be variable since the groups exhibit a fission-fusion pattern. A tribe of about a hundred will split into small groups during the day while looking for food, and then come back together to sleep. They sleep on trees in nests they construct. Unlike Common Chimpanzees, who are known to hunt monkeys, Bonobos are primarily frugivores, although they do eat insects and have been observed occasionally catching small mammals such as squirrels and duikers.
There are instances in which non-human primates have been reported to have expressed joy. One study analyzed and recorded sounds made by human babies and Bonobos when they were tickled. It found although the Bonobo's laugh was a higher frequency, the laugh followed a similar spectrographic pattern to human babies.
As the Bonobo's habitat is shared with people, the ultimate success of conservation efforts will rely on local and community involvement. The issue of parks vs. people is very cogent in the Cuvette Centrale, the Bonobo's range. There is strong local and broad-based Congolese resistance to establishing national parks, as indigenous communities have often been driven from their forest homes by the establishment of parks. In Salonga, the only existing national park in the Bonobo habitat, there is no local involvement, and recent surveys indicate that the Bonobo, the African Forest Elephant, and other species have been severely devastated by poachers and the thriving bushmeat trade. In contrast to this, there are areas where the Bonobo and biodiversity still thrive without any established parks, due to the indigenous beliefs and taboos against killing Bonobos.
In 1995, concern over declining numbers of Bonobos in the wild led the Zoological Society of Milwaukee in Milwaukee, Wis., with contributions from Bonobo scientists around the world, to publish the Action Plan for Pan paniscus: A Report on Free Ranging Populations and Proposals for their Preservation. The Action Plan compiles population data on Bonobos from 20 years of research conducted at various sites throughout the Bonobo's range. The plan identifies priority actions for Bonobo conservation and serves as a reference for developing conservation programs for researchers, government officials and donor agencies.
Acting on Action Plan recommendations, the ZSM developed the Bonobo and Congo Biodiversity Initiative (BCBI). This program includes habitat and rain-forest preservation, training for Congolese nationals and conservation institutions, wildlife population assessment and monitoring, and education. The Zoological Society has conducted regional surveys within the range of the Bonobo in conjunction with training Congolese researchers in survey methodology and biodiversity monitoring. The Zoological Society’s initial goal was to survey Salonga National Park to determine the conservation status of the Bonobo within the park and to provide financial and technical assistance to strengthen park protection. As the project has developed, the Zoological Society has become more involved in helping the Congolese living in Bonobo habitat. The Zoological Society has built schools, hired teachers, provided some medicines, and, as of 2007, started an agriculture project to help the Congolese learn to grow crops and depend less on hunting wild animals.
During the wars in the 1990s, researchers and international non-governmental organizations (NGOs) were driven out of the Bonobo habitat. In 2002, the Bonobo Conservation Initiative initiated the Bonobo Peace Forest Project in cooperation with national institutions, local NGOs and local communities. The Peace Forest Project works with local communities to establish a linked constellation of community-based reserves, managed by local and indigenous people. Although there has been only limited support from international organizations, this model, implemented mainly through DRC organizations and local communities, has helped bring about agreements to protect over of the Bonobo habitat. According to Dr. Amy Parish, the Bonobo Peace Forest "…is going to be a model for conservation in the 21st century.
This initiative has been gaining momentum and greater international recognition and has recently gained greater support through Conservation International, the Global Conservation Fund, United States Fish and Wildlife Service's Great Ape Conservation Fund, and the United Nations' Great Apes Survival Project.
With grants from the United Nations, USAID, the U.S. Embassy, the World Wildlife Fund and many other groups and individuals, the Zoological Society also has been working to:
Starting in 2003, the U.S. government allocated $54 million to the Congo Basin Forest Partnership This significant investment has triggered the involvement of international NGOs to establish bases in the region and work to develop Bonobo conservation programs. This initiative should improve the likelihood of Bonobo survival, but its success may still depend upon building greater involvement and capability in local and indigenous communities.
The Congo is setting aside more than of rain forest to help protect the endangered Bonobo,in this Central African country. U.S. agencies, conservation groups and the Congolese government have come together to set aside of tropical rain forest, the U.S.-based Bonobo Conservation Initiative. The area amounts to just over 1 percent of vast Congo - but that means a park larger than the state of Massachusetts.
The Bonobo population is believed to have declined sharply in the last 30 years, though surveys have been hard to carry out in war-ravaged central Congo. Estimates range from 60,000 to fewer than 5,000 living, according to the World Wildlife Fund.
In addition, concerned parties have addressed the crisis on several science and ecological websites. Organizations like the World Wide Fund for Nature, the African Wildlife Foundation, and others are trying to focus attention on the extreme risk to the species. Some have suggested that a reserve be established in a less unstable part of Africa, or on an island in a place like Indonesia.