These intelligent, social animals (Pan troglodytes) are very closely related to human beings, and give us some indication of the kind of animal from which we evolved. Indeed, chimps have a number of characteristics that were once thought to be exclusively human. For example, they are able to construct and use simple tools - tasks that few other animals, except humans and orangutans, are capable of. One tool commonly used by chimps is a probe, made of a thin twig stripped of leaves, which is inserted into termite nests to extract these insects, which are then eaten.
Chimps live in groups comprising 15-80 animals, which have complex social structures. The dominant males are not necessarily the biggest or strongest individuals, but the ones best able to recruit the most allies. Chimps are territorial, and neighbouring groups are often aggressive towards one another. Indeed, chimps share an unpleasant characteristic with humans: they go to war, and sometimes individuals of one group will hunt and kill members of a neighbouring group.