The sexual activity of common chimps, which by human standards seems obsessive to the point of mania, is almost puritanical by bonobo standards. The average number of penile thrusts in an average copulation—a measure of sexual intensity that primatologists are drawn to, in part because it can be quantified—is around forty-five for bonobos, compared to less than ten for chimps. The number of copulations per hour is 2½ times greater for bonobos than for chimps—although these observations are for bonobos in captivity, where they may have more time on their hands or more need for mutual comfort than when they are free. Less than a year after giving birth, bonobo females are ready to resume their lives of sexual abandon; it takes three to six years for chimp females.20
Bonobos use sexual stimulation in everyday life for many purposes besides mere satisfaction of the erotic impulse—for quieting infants (a practice said once to have flourished also among Chinese grandmothers), as a means of resolving conflict among adults of the same sex, as barter for food, and as a generic, all-purpose approach to social bonding and community organization. Less than a third of the sexual contacts among bonobos involve adults of opposite sexes. Males will rub rumps together or engage in oral sex in ways unheard of among the more prudish chimps; females will rub their genitalia together, and sometimes prefer it to heterosexual contacts. Females characteristically engage in genital rubbing just before they’re about to compete for food or for attractive males; it seems to be a way of reducing tension. In times of stress, a bonobo male will spread his legs and present his penis to his adversary in a friendly gesture.
Despite these differences in nuance, bonobos are still chimpanzees. There’s a male dominance hierarchy, although not nearly as pronounced as among common chimps; dominant males have preferential access to females, although males do not always dominate females; there are submissive gestures and greetings; the size of groups is about the same as with chimps, a few dozen; adolescent females wander over to adjacent groups; the males preferentially hunt animal prey, although apparently not in hunting parties; males are proportionately larger than the females by about the same ratio as among chimps; and encounters between groups sometimes become violent—although groups may also on encountering one another, behave very peaceably and laid-back. Infanticide and all other killing of bonobo by bonobo are, so far, unknown. Their standard initial response on meeting unfamiliar humans, as we ourselves experienced, is a very chimp-like, and adequately intimidating, charging display.
Grooming is most frequent between males and females and least common between males and males, the reverse of chimp practice. The grin serves not mainly as a gesture of submission, but performs a range of functions similar to those of the human smile. Male bonding is much weaker than in chimp society, and the social position of females much stronger. Certain mothers and sons associate closely until the son becomes an adult; among chimps the relationship tends more often to be broken off when the young male reaches adolescence. Social skills for resolving conflicts are much more highly developed among the bonobos than among the chimps, and dominant individuals are much more generous in making peace with their adversaries.
If we feel a certain revulsion at having hamadryas baboons as relatives, we may take some comfort from our connection with the gibbons and the bonobos. Indeed, we’re far more closely related to the apes than to the monkeys. Chimps and bonobos are certainly members of the same genus and, according to some taxonomic classifications, even the same species. Given that, it’s startling how different they are from one another. Perhaps many of the distinctions between the two—ranging from the frequency, increased variety, and social utility of sex to the relatively higher status of females—are due to the evolution in the bonobos of a new step: abandoning the monthly badge of ovulation, graduating from estrus. Perhaps when ovulation is not evident at a glance or a sniff, females can be viewed as more than sexual property.
The primates are so rich in potential that even a small change in anatomy or physiology may provide an aperture to a universe never dreamt of in the rude sleeping pallets made each night in the low branches of the once-vast tropical forests.
SOME SKETCHES FROM LIFE
Monkeys:
Monkeys are liable to many of the same non-contagious diseases as we are … Medicines produced the same effect on them as on us. Many kinds of monkeys have a strong taste for tea, coffee, and spirituous liquors: they will also, as I have myself seen, smoke tobacco with pleasure. Brehm asserts that the natives of north-eastern Africa catch the wild baboons by exposing vessels with strong beer, by which they are made drunk. He has seen some of these animals, which he kept in confinement, in this state; and he gives a laughable account of their behaviour and strange grimaces. On the following morning they were very cross and dismal; they held their aching heads with both hands, and wore a most pitiable expression: when beer or wine was offered them, they turned away with disgust, but relished the juice of lemons. An American monkey, an Ateles, after getting drunk on brandy, would never touch it again, and thus was wiser than many men. These trifling facts prove how similar the nerves of taste must be in monkeys and man, and how similarly their whole nervous system is affected.21
Eastern Mountain Gorillas:
When two animals meet on a narrow trail the subordinate gives the right-of-way; subordinates also yield their sitting place if approached by superiors. Sometimes the dominant animal intimidates the subordinate by starting at it. At most it snaps its mouth or taps the body of the other animal with the back of its hand.22
Monkeys:
[P]hallic threatening, derived from a sexual domination gesture (mounting), … has been described among many monkey species in both the Old World and the New. Among guenons and baboons, a few males always sit with their back to the group keeping guard, displaying their strikingly colored penis and their sometimes similarly strikingly colored testicles. If a stranger to the group approaches too closely, the guards actually have an erection; so-called “rage copulations” also take place.23
Squirrel monkeys:
The displaying monkey vocalizes, spreads one thigh, and directs the fully erect penis toward the head or chest of the other animal. The display is seen in its most dramatic form when a new male is introduced into an established colony of squirrel monkeys … Within seconds all males begin to display to the strange monkey, and if the new male does not remain quiet with its head bowed, it will be viciously attacked.24
Brown capuchin monkeys:
An estrous female will shadow the dominant male for days. At frequent intervals she approaches him closely, grimaces at him while giving a distinctive vocalization, pushes him on the rump, and shakes branches at him. When she is ready to copulate, she charges him, he runs away, she follows, and when he stops running, they mate.25
Orangutans:
At midcycle, a female orangutan will seek out the dominant male in her vicinity. At other times during her cycle, young males and subordinate males will sometimes cluster around her and it appears that she is being forced to mate with them. She resists, she screams, she fights, but they mate with her anyway. It is either a good act, or it’s the equivalent to rape. Primatologists try not to use that term. People tend to get upset.26