Today, all humans belong to one population of "Homo sapiens sapiens", which is individed by species barrier. However, according to the "Out of Africa" model this is not the first species of hominids: the first species of genus "Homo", "Homo habilis", evolved in East Africa at least 2 Ma, and members of this species populated different parts of Africa in a relatively short time. "Homo erectus" evolved more than 1.8 Ma, and by 1.5 Ma had spread throughout the Old World.