Homo is the genus that comprises the species Homo sapiens, which includes modern humans, as well as several extinct species classified as ancestral to or closely related to modern humans—as for examples Homo habilis and Homo neanderthalensis.The genus is about 2.8 million years old; it first appeared as its earliest species Homo habilis, which emerged from the genus Australopithecus, which itself had previously split from the lineage of Pan, the chimpanzees.Taxonomically, Homo is the only genus assigned to the subtribe Hominina which, with the subtribes Australopithecina and Panina, comprise the tribe Hominini (see evolutionary tree below). All species of the genus Homo plus those species of the australopithecines that arose after the split from Pan are called hominins.