A river split our two closest relatives into warlike chimps and peaceful bonobos
Chimpanzees live north of the Congo River, bonobos to its south, and the two were treated as one species until 1928. They parted ways only about a million years ago, yet chimp groups tend to be larger, rougher and run by males, while bonobo societies are gentler and led by females.
Together they form the genus Pan, and they are equally close to us. Human and chimpanzee lineages split somewhere between five and twelve million years ago. In 1973 Mary-Claire King reported that human and chimp DNA was 99 percent identical; later estimates dropped to about 94 percent, but current work puts the gap between humans, chimpanzees and bonobos back at roughly 1 to 1.2 percent. Both apes make sophisticated tools, build fresh sleeping nests of branches every night and may even maintain distinct local cultures. Jane Goodall pioneered field studies of chimpanzees.
Physically they are built for trees. A chimpanzee's arms are longer than its legs and span about one and a half times its height, and on the ground it usually knuckle-walks on clenched fists. Males stand up to 1.2 metres and weigh 40 to 60 kilograms. Bonobos are slimmer, with even longer arms, and walk upright more often. Both species mostly eat fruit, live in large social communities, and can survive beyond 30 years.
The names carry some odd baggage. Lorenz Oken coined Pan in 1816, apparently after the Greek god, and the zoological naming commission made it official in 1895. Johann Friedrich Blumenbach had already named the chimpanzee troglodytes, after a cave-dwelling African people described by classical geographers. The word chimpanzee appeared in The London Magazine in 1738, supposedly meaning mockman in a Bantu language, and the casual chimp likely dates from the late 1870s.
For a long time no chimpanzee fossils were known at all. Then in 2005 Sally McBrearty and colleagues described fossils from Kenya, showing that chimpanzee relatives shared the East African Rift Valley with early humans in the Middle Pleistocene. Today both species are endangered.
Source: Pan (genus)
