Chimpanzee Hunting Behavior and Human Evolution
Chimpanzees are efficient predators that use meat as a political and reproductive tool. Are there implications for the evolution of human behavior?
This article originally appeared in the May-June 1995 issue of American Scientist.
In the early 1960s, when the british primatologist Jane Goodall first observed wild chimpanzees hunting and eating meat in Gombe National Park, Tanzania, it was widely believed that these animals were strict vegetarians. Skeptics suggested that the diet of the Gombe chimpanzees was aberrant. Others suggested that the quantity of meat the chimpanzees ate was trivial. After more than 30 years of research, however, it is now clear that meat is a natural part of the chimpanzees' diet. Indeed, hunting has been observed at most of the other sites where chimpanzees are studied across central Africa. And, it turns out, a chimpanzee community may eat several hundred kilograms of meat in a single year.
To many anthropologists this is a surprising development. Of all the higher primates, only human beings and chimpanzees hunt and eat meat on a regular basis. The similarities pose an intriguing prospect: Might the close evolutionary relationship between chimpanzees and human beings provide some clues to the evolution of our own behavior? We do know that the earliest bipedal hominids, the australopithecines, evolved in Africa about 5 million years ago and that they shared a common ancestor with modern chimpanzees shortly before that time. Unfortunately, the evidence for the occurrence of meat-eating among the early australopithecines is spotty at best. Primitive stone tools that were made 2.5 million years ago suggest that early hominids had the means to carve the flesh from large carcasses, but we know very little about their diets before that time. Were they hunters or perhaps, as many anthropologists now argue, scavengers? The behavior of chimpanzees may provide a window through which we can see much that has been lost in the fossil record.
There are also some interesting subtleties to the chimpanzees' hunting behavior that need to be addressed. Although chimpanzees can and do hunt alone, they often form large hunting parties consisting of more than 10 adult males, plus females and juveniles. Chimpanzees also go on "hunting binges" in which they kill a large number of monkeys and other animals over a period of several days or weeks. Such binges have always been a little mysterious. What could incite a chimpanzee to suddenly forgo plant foraging and turn to hunting? Are there social or ecological factors associated with the impetus to hunt? What ecological effects does the chimpanzees' predatory
behavior have on their prey?
In the past five years I have been mindful of such questions as I observed the chimpanzees and their primary prey at Gombe, the red colobus monkey. Although we are only beginning to understand some of the causes and consequences
of the chimpanzees' actions, what we have discovered is more complicated and more interesting than anyone suspected. For chimpanzees, meat is not only another way to get nutrients like fat and protein, but a means to make
political bonds and gain access to sexually receptive females.