The First Humans: Classification
Increasing brain size, remodeled teeth, and hips and lower limbs redesigned for walking are major hallmarks of the human tribe, Hominini. This tribe holds at least two genera: the almost extinct Australopithecus ("southern ape), which evolved in Africa over 4 million years ago, and Homo ("man"), which appeared about 2 million years ago.
Homo features a relatively bigger brain, thus a bigger brain case, and a smaller, less projecting face, with an open U-shaped tooth row. Arms are shorter in relation to legs, and hip bones permit both bipedal walking and giving birth to babies with large heads.
The word "hominid" refers to members of the family of humans, Hominidae, which consists of all species on our side of the last common ancestor of humans and living apes. Hominids are included in the superfamily of all apes, the Hominoidea, the members of which are called hominoids. Although the hominid fossil record is far from complete, and the evidence is often fragmentary, there is enough to give a good outline of the evolutionary history of humans.

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