Common chimpanzees travel around the forests and savannas of central Africa on all fours. This knuckle-walking, uses their characteristic long arms and short legs. Sharing 98 percent of human genes, they are our closest living relative and probably the most intelligent non-human animal. They show learned behaviours, long memories and some extraordinary use of tools. Chimpanzees are very similar to humans both in appearance and in their complex social behaviours and societies.