From them we may learn much concerning the behavior of our earliest primate prototypes, because behavior, unlike bones, teeth, or tools, does not fossilize. Throughout the eighteenth century there remained a considerable amount of confusion in distinguishing between orangutans, chimpanzees, and gorillas. It was not until 1847, on the basis of a single skull from Gabon, that the gorilla was confirmed as a separate genus from the chimpanzee. It is this subspecies most frequently seen in captivity and mounted in museum collections. The Virunga population were the subjects of Dian Fossey's field study.
None is in captivity.
At least 10,000 eastern lowland gorillas remain in the wild in eastern Zaire, and less than two dozen live in captivity. The distribution of gorillas in Africa is discontinuous. Terrestrial vs. Arboreal Gorillas are mainly ground-living, but where trees are strong enough and fruiting, whole groups can be seen up them, even the mature males. The height above the ground that animals build the nests in which they sleep at night is inversely proportional to their weight, with the silverbacks usually being on or close to the ground. Gorilla and chimpanzee nests look alike, but can usually be told apart because chimpanzees nest so much higher up trees than do gorillas.