Wild chimpanzees are indigenous only to Africa, can have a life-span of more than 50 years, and weigh up to 200 pounds. Chimpanzees have demonstrated cooperative problem-solving, the representational use of numbers, and the ability to comprehend and use language, including proper syntax. As with humans, the mother-infant bond among chimpanzees is extremely close. The chimpanzee mother nurses her infant for four to five years. The growing chimpanzee child then spends a prolonged childhood, until age ten or eleven, living with his or her family.
Wild chimpanzees make and use a variety of tools for gathering and preparing food.
For example, the chimpanzees of West Africa practice a stone tool culture. Their hammers and anvils, used to crack hard nuts, are similar to the tools of our own hominid ancestors. Chimpanzees seek out and use certain plants medicinally, to treat symptoms of various illnesses. Scientists following chimpanzees in the rainforest have been led to a variety of formerly unknown plant species that have pharmaceutical uses ranging from antibiotics to antiviral agents. In the late 1950s, the U.S. Air Force captured more than 100 chimpanzees in the African jungle and began using them to test the effects of space flight.