[3] The orangutans were reassigned to the family Hominidae (great apes), which already included humans; and the gorillas were grouped as a separate tribe (Gorillini) of the subfamily Homininae.

[6] Potts (2010) in addition uses the name Hominini in a different sense, as excluding Pan, and uses "hominins" for this, while a separate tribe (rather than subtribe) for chimpanzees is introduced, under the name Panini.

Genetic analysis combined with fossil evidence indicates that hominoids diverged from the Old World monkeys about 25 million years ago (Mya), near the Oligocene-Miocene boundary.

Hylobatidae (gibbons) Ponginae (orangutans) Gorillini (gorillas) Panina (chimpanzees) Ardipithecus (†) Praeanthropus (†) Australopithecus/Paranthropus robustus (†2) Australopithecus garhi (†2.5) Homo (humans) Both Sahelanthropus and Orrorin existed during the estimated duration of the ancestral chimpanzee–human speciation events, within the range of eight to four million years ago (Mya).

Different chromosomes appear to have split at different times, with broad-scale hybridization activity occurring between the two emerging lineages as late as the period 6.3 to 5.4 Mya, according to Patterson et al. (2006),[17] This research group noted that one hypothetical late hybridization period was based in particular on the similarity of X chromosomes in the proto-humans and stem chimpanzees, suggesting that the final divergence was even as recent as 4 Mya.

Wakeley (2008) rejected these hypotheses; he suggested alternative explanations, including selection pressure on the X chromosome in the ancestral populations prior to the chimpanzee–human last common ancestor (CHLCA).

[22][23] In the year 2000, the discovery of Orrorin tugenensis, dated as early as 6.2 Mya, briefly challenged critical elements of that hypothesis,[24] as it suggested that Homo did not in fact derive from australopithecine ancestors.