While the West African Chimp became the first subspecies nearly five hundred thousand years ago, its sister clade, the Nigeria-Cameroon Chimp, is the newest discovered subspecies. Thus, the Central and Eastern Chimps are monophyletic and form the second lineage as they are the closest related subspecies. Researchers believe they formed a single population as recently as one hundred thousand years ago. Causes of speciation of the Common Chimp included habituation, strong directional selection, and genetic drift. Moreover, genetic differences between Western and Central Chimps are so great; they are stronger than those between any two human populations. Chimpanzees dwell in the …show more content…
In response to physical contact, chimpanzees exhibit vocalizations, hand gestures, and facial expressions to respond to one another. Chimpanzees for example wrestle and tickle, and in return, inhale, exhale, breath, and pant according to the emotions they are having. Also, laughter occurs not only in humans, but also chimpanzees. Laughter has adapted from humans and was proved to be true in a mirror test when an animal identifies himself and laughs through mirror