Paul Belloni Du Chaillu was a French-American traveler, zoologist, and anthropologist. He became famous in the 1860s as the first modern European outsider to confirm the existence of gorillas, and later the Pygmy people of central Africa. He later researched the prehistory of Scandinavia.

Gorillas are herbivorous, predominantly ground-dwelling great apes that inhabit the tropical forests of equatorial Africa. The genus Gorilla is divided into two species: the eastern gorilla and the western gorilla, and either four or five subspecies. The DNA of gorillas is highly similar to that of humans, from 95 to 99% depending on what is included, and they are the next closest living relatives to humans after chimpanzees and bonobos.