The Brutal Ape vs. the Sexy Ape?
The Make-Love-Not-War Ape
Since the mid-1980s, the closely related, but only recently studied, bonobo has come to serve as an evolutionary counterpoint to the chimpanzee. They may look very much like chimpanzees—they were once called pygmy chimpanzees—but bonobos appear to be an ape of a different character. Studies of bonobos reveal a society molded by cooperation, alliance formation and recreational sex "as social communication." As primatologist Frans de Waal of Emory University puts it, "...[T]he high points of bonobo intellectual life are found not in cooperative hunting or strategies to achieve dominance but in conflict resolution and sensitivity to others."
Female bonobos band together in coalitions to dominate males, avoiding the sort of physical domination and sexual coercion that male chimpanzees routinely inflict on their females. Such female coalitions are nearly unknown among chimpanzees, where the male bonds are the cause and consequence of everything from communal hunting of small game to the fierce defense of their territorial borders.
Then there is the sex. Bonobos are often said to be, more than anything else, the sexy ape. They mate more often, in more positions and with more recreational than procreational intent than any mammal other than Homo sapiens. Copulation rates recorded by de Waal and Parish for captive bonobos in the San Diego Zoo and at the Yerkes Regional Primate Center in Atlanta are sky-high compared with such activities among wild chimpanzees. Bonobos also engage in female-female pairings, in which two females rub their genital swellings together ("GG rubbing" in the lexicon of bonobo researchers) to ease tensions between individuals. Male bonobos will also engage in same-sex genital rubbing. Such same-sex bonding is absent in chimpanzee society.
Relative to chimpanzees, bonobo society appears to be sex oriented and "less dominated" by males. As de Waal states, "The chimpanzee resolves sexual issues with power; the bonobo resolves power issues with sex."
An even more striking difference between female chimpanzees and bonobos is said to link the bonobos more closely to the human family tree. The females of nearly all mammalian species are reproductively active only during a constricted time period surrounding ovulation. This estrus period characterizes all of the higher primates, except human beings. Females of our species, although more likely to conceive around the time of ovulation, are freed from the bonds of a strictly defined period of "heat." The result is that sex serves not only for procreation, but also as a mechanism of social communication and reinforcement of long-term pair bonds.
Bonobo females are often said to be released from the bonds of estrus because they maintain their sexual swellings for a much longer portion of their menstrual cycles than chimpanzees do and therefore mate throughout much of the cycle. Since female apes of either species show little interest in mating except when they are swollen, this translates into more sex for the bonobos. Being "released from estrus," bonobos have come to use sex as much for communicating with males as for conceiving offspring, as in our own species.
In war as well as in romance, bonobos and chimpanzees appear to be strikingly different. When two bonobo communities meet at a range boundary at Wamba, a research site in the lowland rain forests of the Democratic Republic of Congo, bonobo researcher Takayoshi Kano observed that not only is there no lethal aggression as sometimes occurs in chimps, there actually may be socializing and sex between females and the enemy community's males.
When it comes to hunting and meat eating, we see a final striking contrast between bonobos and chimps. Bonobos catch monkeys in their rainforest habitat almost as well as chimpanzees do, but they don't seem to know what to do with them. Bonobos capture baby monkeys and then use them as dolls or playthings for hours, only to release the monkey unharmed (though worse for the wear) when they become bored with them. It's as if the protein and fat value of the prey hasn't dawned on their kinder, gentler nature.