Comparing Chimpanzees and Bonobos
Despite Many Similarities, Behavior Differs Significantly
Chimpanzees and bonobos are the closest living relatives of humans, sharing around 94% of their DNA with us, their less hirsute cousins. Their relationship to one another is far closer — both are members of the genus Pan (in fact its only two members), with Pan troglodytes describing the common chimpanzee and Pan paniscus describing the bonobo, which has also been called the pygmy or gracile chimpanzee. Chimps and bonobos only branched from their common lineage about one million years ago, possibly when the formation of the Congo River bisected their habitat.
In the past few years, articles in the popular media have portrayed a curious dichotomy, with aggressive, patriarchal chimpanzees pitted against the matriarchal, peace-loving bonobos. This cut-and-dried view ignores the complexity of the actual behavior of these two species, but there does seem to be a kernel of truth at the heart of the issue.
Physical Differences Between Chimps and Bonobos
Despite their colloquial name of “pygmy” chimpanzee, bonobos are actually roughly the same size as common chimpanzees, being only slightly shorter and thinner, with smaller heads. Common chimpanzees have shorter limbs than the more gracile bonobo, and a more prominent brow ridge. Bonobos apparently walk upright more often than chimps, and when walking quadrupedally employ a method of knuckle walking more similar to that of the orangutan than the chimpanzee.
Social Behavior in Chimps and Bonobos
Both species of primates are evidently capable of altruism, empathy, deception, self-recognition, foresight, and culture in the form of knowledge passed from one to the other. Both are also capable of learning sign language and understanding the spoken language of humans; the extent to which they possess all of these qualities is still a matter of some debate. Chimps and bonobos are also equally capable of making and using tools, like termite sticks and even rudimentary spears, and both cooperate with members of their communities to achieve common goals.
There are some marked differences, however. Chimpanzees seem to be significantly more aggressive, both toward outsiders and members of their own tribes; male chimpanzees are known to kill other males in territorial disputes. Chimpanzee societies are based on a rigid hierarchy, with an alpha male leading a hunting troop of subordinate males. They are also skilled at catching and killing monkeys for food, and have been known to cannibalize other chimpanzees. And, as several recent cases have made clear, they have no qualms about killing humans if they feel that they are threatened.
Bonobos, on the other hand, live in much more egalitarian societies, led by loose coalitions of females and their sons, with whom they seem to have a special bond. While hunting for monkeys has been observed on a few occasions, this behavior is apparently rare, and bonobos generally stick to a frugivorous diet. They also seem to be far less aggressive than common chimpanzees; bullying behavior has been noted among captive bonobos, but there have been no reports of either captive or wild bonobos killing other bonobos or humans. Bonobos, particularly in the wild, are not as well studied as chimpanzees, so any impression of their peaceful nature may have to be modified as more observations are made.
Bonobos and Sexual Behavior
In contrast to chimpanzees’ more violent methods of solving disputes, bonobos seem to use sex as a sort of bonding tool and way of settling conflicts. While studies have shown that, on average, male chimpanzees and male bonobos have about the same number of copulations, the sexual contact of bonobos is in general far more common and far-reaching, comprising oral sex, group sex, genital rubbing, and many other contacts between same sex and opposite sex partners. Gender, age and family relation also appear to be no barrier, as all engage in frequent sexual activity in order to resolve conflicts, calm or express excitement, cement alliances, or simply to relax or alleviate boredom. The only relationship that seems to preclude sexual contact is that between mother and son, which appears to be a taboo coupling.
Additional Source:
De Waal, Frans (2006). Our Inner Ape: A Leading Primatologist Explains Why We Are Who We Are. Riverhead Trade. ISBN: 1594481962.
Common Chimpanzee
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Bonobo
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