Shadows of Forgotten Ancestors

Chimps recognize one another’s individual voices, and a distinctive pant-hoot may summon an ally or relative from a considerable distance. In answering a pant-hoot from, say, an adjacent valley, they lift their heads and purse their lips as if they were on stage at La Scala. Up close, they have an uncanny ability—“uncanny” means only that we haven’t been smart enough to figure it out yet—to communicate with one another, not just about such straightforward matters as sex or dominance, but about much more subtle matters, such as hidden dangers, or buried food supplies. A classic set of experiments was done by the psychologist E. W. Menzel:[Menzel] maintained four to six young chimpanzees in a large outdoor enclosure that was also connected to a smaller holding cage. He restrained all but one animal in the holding cage, while showing this chosen “leader” the hidden location of either an amount of food or an aversive stimulus such as a stuffed snake. The leader was then returned to the holding cage, and the whole group was released. According to Menzel’s reports, the variable behavior of the animals indicated that they “seemed to know approximately where the object was, and what sort of object it was, long before the leader reached the spot where it had been hidden” … If the goal was food, they ran ahead looking in possible hiding places; if it was a stuffed alligator or snake, they emerged from their cage showing piloerection [their hair standing on end] and staying close to their companions. If the hidden item was an alligator or snake, they became very cautious in their approach and often mobbed the area, hooting in the direction of the hidden item and hitting at it with sticks. If the hidden item was food, the animals searched the area intensively and showed little fear or distress. The behaviors occurred even if the aversive stimulus had been removed before the animals were released from the holding cage, so it was not the item itself that produced these reactions.In the food tests, one male (Rocky) began to monopolize the food supply when it was located. When Belle, a female, served as leader, she attempted to avoid indicating the location of the food cache, but Rocky could often extrapolate from her line of orientation and find the food. If Belle were shown two caches, one large and one small, she would lead Rocky to the small one and, while he was busy eating, run to the larger one which she would share with other individuals. Menzel concluded that chimpanzees could communicate the direction, amount, quality, and nature of the goal, as well as attempt to conceal at least some of this information, but precisely how chimpanzees achieve such communication is still not known.²⁷

The only possibilities seem to be gestures and speech.

Chimps have hundreds of different kinds of food and crave dietary variety. They eat fruit, leaves, seeds, insects, and larger animals, sometimes dead ones. Caterpillars are delicacies, and the discovery of an infestation of caterpillars becomes a memorable gastronomic event. They’re known to eat soil from cliff faces, presumably to provide mineral nutrients such as salt. Mothers will offer choice tidbits of food to their infants and will snatch unusual, possibly dangerous, foods from their mouths. In the wild, adults share food occasionally, often in response to begging. There are no set mealtimes; they snack throughout the day. As a foraging party moves on, one of its members may carry a branch still laden with berries or leaves to munch as she rambles.

When in the middle of the night, in their beds of leaves in the high branches, they are awakened by the cries of predators, they clutch each other in fright, their urine and feces raining down on the forest floor below.

They love to play, children (whose energy is prodigious) more than adults, but even adult play is common—especially when there’s enough to eat and large numbers of chimps gather together. Play often involves, but is not restricted to, mock fighting.

Chimp males are protective toward females and the young. They will readily risk their own lives to protect “women and children” from attack, or to rescue a youngster in trouble. Goodall writes, “Often it seems that a male cannot resist reaching out to draw an infant into a close embrace, to pat him, or to initiate gentle play.”²⁸ When a male is discovered in flagrante delicto with a female, which is often, an infant may rush up to punch the male in the mouth or jump on the back of the female, most often his mother.* In such situations the male’s tolerance frequently exceeds human limits.

But in a display competition for dominance, all this good-natured equanimity vanishes, and a male who ordinarily is protective of infants may pick up a small, innocent bystander and slam it to the ground in his rage. When an unfamiliar female is discovered in their territory, chimps are known to seize her infant by the ankles and smash it against the rocks.²⁹