<P> The genus Pan is part of the subfamily Homininae, to which humans also belong . The lineages of chimpanzees and humans separated in a drawn - out process of speciation over the period of roughly between twelve and five million years ago, making them humanity's closest living relative . Research by Mary - Claire King in 1973 found 99% identical DNA between human beings and chimpanzees . For some time, research modified that finding to about 94% commonality, with some of the difference occurring in noncoding DNA, but more recent knowledge states the difference in DNA between humans, chimpanzees and bonobos at just about 1%--1.2% again . </P> <P> The chimpanzee fossil record has long been absent and thought to have been due to the preservation bias in relation to their environment . However, in 2005, chimpanzee fossils were discovered and described by Sally McBrearty and colleagues . Existing chimpanzee populations in West and Central Africa are separate from the major human fossil sites in East Africa; however, chimpanzee fossils have been reported from Kenya, indicating that both humans and members of the Pan clade were present in the East African Rift Valley during the Middle Pleistocene . </P> <P> A chimpanzee's arms are longer than its legs . The male common chimp stands up to 1.2 m (3.9 ft) high . Male adult wild chimps weigh between 40 and 60 kg with females weighing between 27 and 50 kg . When extended, the common chimp's long arms span one and a half times the body's height . The bonobo is slightly shorter and thinner than the common chimpanzee, but has longer limbs . In trees, both species climb with their long, powerful arms; on the ground, chimpanzees usually knuckle - walk, or walk on all fours, clenching their fists and supporting themselves on the knuckles . Chimpanzees are better suited for walking than orangutans, because the chimp's feet have broader soles and shorter toes . The bonobo has proportionately longer upper limbs and walks upright more often than does the common chimpanzee . Both species can walk upright on two legs when carrying objects with their hands and arms . </P> <P> The chimpanzee is tailless; its coat is dark; its face, fingers, palms of the hands, and soles of the feet are hairless . The exposed skin of the face, hands, and feet varies from pink to very dark in both species, but is generally lighter in younger individuals and darkens with maturity . A University of Chicago Medical Centre study has found significant genetic differences between chimpanzee populations . A bony shelf over the eyes gives the forehead a receding appearance, and the nose is flat . Although the jaws protrude, a chimp's lips are thrust out only when it pouts . </P>

What is the average weight of a chimpanzee
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