An experiment illustrates these differences: Parish (1994) presented a simulated termite mound (with food) to groups of both common chimpanzees
however, reported that TTV sequences from pigmy chimpanzees are closely related to viruses from human genotypes 2 and 3, while that sequences obtained from common chimpanzees
were genotypes 5 and 6, the latter only at the protein level.
The scientists compared Orrorin's upper leg to corresponding specimens from 130 modern humans, 49 common chimpanzees
, 14 pygmy chimps, 59 gorillas, 32 orangutans, and nine fossil ancestors of people.
Cameroon, Gabon, and Republic of Congo are home to most Central African common chimpanzees
(Pan troglodytes troglodytes).
At around that time, there may have been as many as two million common chimpanzees
spread over most of tropical Africa, in 25 countries from Tanzania in the east to Senegal in the west.
As long as we have not justified in detail why we are enlisting common chimpanzees
or bonobos in an analogy that excludes orangutans or baboons, we will have to choose one or the other of the perspectives put forth.
Outgroups were provided by the control-region sequences of common chimpanzees
, pygmy chimpanzees, and gorillas that were obtained by Foran et al.