A new study conducted by American researchers has found that ever since the lineage diverged, chimpanzees, and not humans, have experimented more with sex.
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But the question that remains is whether male chimps inherited this unique ability from the last shared common ancestor or did they evolve it later, New Scientist reported.
Michael Jensen-Seaman and Scott Hergenrother at Duquesne University in Pennsylvania team, trying to resolve the question, looked at ACPP - an enzyme in semen, which prevents it from coagulating into a plug.
They found that the enzyme is four times as abundant in human semen as in the chimp semen.
For clues about the human-chimp ancestor having similar levels of enzyme to humans or chimps, the team turned towards the gorillas, which separated from the ancestor a few million years earlier.
The test showed that gorillas regulate ACPP similar to humans, which suggests that the human-chimp ancestor did the same.
However, it is difficult to be sure whether the chimps made the change after having split from humans.
It is also possible that the human-chimp ancestor had chimp-like behaviour and that our lineage has since reverted to a gorilla-like condition.
Source-ANI