The more
anthropomorphic primates of the
Hominini tribe are placed in the 'Hominina' subtribe. They are characterized by the evolution of an increasingly erect
bipedal locomotion. The only extant species is ''
Homo sapiens''. Fossil records indicate this subtribe branched from the common ancestor with the
chimpanzee lineage about 3 to 5 million years ago.
This subtribe is usually described to include ''
Australopithecus'', ''
Paranthropus'', ''
Sahelanthropus'', ''
Orrorin'', ''
Ardipithecus'', ''
Kenyanthropus'', and ''
Homo''. However, the exact makeup is still under debate, as some scientists struggle to determine the order of descent in
human evolution.
Key features of this group involve various adaptations for living
terrestrially instead of
arboreally. One feature is an erect bipedal stance and the skull placed on top of the vertebral column. The feet are not
prehensile unlike the rest of primates, because the first toe is but robust and aligned with the other four. The hands have a developed opposable thumb and are quite adept at manipulating objects.
Currently it is believed that about 2.6 million years ago, ''Australopithecus'' began to diverge into two paths, on the one hand to ''Paranthropus'', more robust, specialized in an
herbivorous diet that required a stronger jaw and molars and powerful facial muscles that required a cranial crest to unite them. The other track led to ''Homo'' with a relatively larger brain, more graceful teeth and jaw. Both genera existed at the same time for about a million and a half years.