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The primate family hominidae consists of two commonly accepted genera, Australopithecus and Homo. However, two other genera are proposed. The genus Ardipithecus has recently been described and placed as the earliest common ancestor to all hominids. Also, others accept the genus Paranthropus that I will here include as a member of the genus Australopithecus. I will outline the hominid family as having three genera, Ardipithecus, Australopithecus, and Homo.
When considering human origins it’s important to keep in mind the nature and structure of the primate evolutionary tree. Primates are the product of significant mammalian adaptive radiations which occurred throughout the early Tertiary, ~ 70–50 mya (millions of years ago). Within the development of extant (living) primates, there have also been several adaptive radiations (~ 50 mya-present). The emergence of hominids came from a common ancestor of extant apes and humans from approximately 6–7 mya. Modern apes, (chimpanzees), are not our immediate ancestors or progenitors but rather more appropriately, our siblings. We both exist in the temporal present and have only morphologically distinct parent taxa to serve as a common ancestor. According to this view, the australopithecines, like the ardipithecines, are hominid radiations. One species-level taxa from the ardipithecines gave rise to the australopithecine radiation. Likewise, from this radiation came one Australopithecus species that gave rise to the Homo lineage.
The latter family includes species such as H. habilis, H. erectus and H. sapiens. The relationship between the three commonly accepted species of Homo is subject to some controversy as recent analyses have concluded australopithecine affinities of H. habilis. Some view the emergence of H. erectus as the hallmark of the modern human race. This view is attractive for those wishing to argue regional continuity of H. erectus in Eurasia with modern human populations. This regional approach posits that the various species of hominids out of Africa are members of the same lineage, only separated by time.
Ardipithecus:
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