Hominin

A hominin is a member of the human evolutionary group: modern humans and the extinct species on our side of the family tree. The Smithsonian Institution's Human Origins Program defines the word from Hominini, a formal term in biological classification that sits between the level of genus, such as Homo or Australopithecus, and the level of family, Hominidae.

The neighbouring word hominid is wider, and the two are easily confused. A hominid is a member of the great ape group, which takes in the living Asian great apes (orangutans), the living African great apes (chimpanzees, bonobos and gorillas) and humans together. Hominin is the narrower of the two, and it is the word used when a fossil is being placed relative to us rather than relative to apes in general.

Humans and the African great apes share a common ancestor that lived between 8 and 6 million years ago, and the hominin group covers the human side of that division. Because the group is defined by ancestry rather than by anatomy, a newly found fossil can be argued into or out of it, which is why the naming of individual specimens is often contested long after the bones themselves are described.