Chimpanzee is an African ape. Chimpanzees are one of the four kinds of apes, along with gibbons, gorillas, and orangutans. The chimpanzee ranks as one of the most intelligent animals and resembles human beings more closely than any other animal does.
Chimpanzees have many characteristics that make them interesting and valuable to human beings. Its playfulness and curiosity make it a popular animal at zoos. Young chimpanzees can be tamed and trained easily, and they make excellent circus performers. Scientists use them in medical and psychological research because the animals have many similarities to humans. Most zoologists classify chimpanzees into two species. The first species is known simply as the chimpanzee. It lives throughout much of central Africa, from Lake Victoria in the east to Sierra Leone in the west. Scientists divide this species into three subspecies--the common, or masked, chimpanzee; the tschego; and the eastern, or long-haired, chimpanzee. The second species, known as the bonobo, or pygmy chimpanzee, lives only in Zaire, south of the Congo River and west of the Lualaba River. This article discusses primarily the first species. The body of a chimpanzee. Chimpanzees range in height from 1 metre to a little over 1.5 metres. An adult male chimpanzee weighs about 50 kilograms. An adult female weighs about 40 kilograms. The chimpanzee's body is covered with long, black hair. Like the other apes, the chimpanzee does not have a tail. It has large ears, and its arms are longer than its legs. The chimpanzee's long hands are well adapted for grasping and holding onto objects. In addition, the big toes of the chimpanzee face sideways like thumbs, enabling it to grasp branches with its feet while climbing. Baldness is common among both male and female chimpanzees. The bald area in males forms a triangle on the forehead. The bald patch in female chimpanzees extends from the forehead to the crown of the head. The life of a chimpanzee. Chimpanzees live in forests, including tropical rain forests, and in forested, grassy plains. They move about in search of food and usually range over an area of 25 to 50 square kilometres. Chimpanzees travel in groups that vary in number and change members frequently. There are four chief types of groups: (1) bands of adult males and females, (2) all-male bands, (3) bands of mothers and their infants, and (4) mixed bands of both sexes and all ages. Sometimes a chimpanzee may travel alone. Chimpanzees live both in trees and on the ground. They spend from 50 to 75 per cent of each day in the trees. They sleep in tree nests made of branches, leaves, and twigs. The animals make new nests each night. They build the nests at least 4.5 metres above the ground. When resting during the day, chimpanzees lie along a limb and grasp overhead branches, or they may sprawl out on the ground. Chimpanzees usually walk on all fours, supporting the upper part of their bodies with their knuckles. They seldom stand erect to walk or run, except when excited or to see over tall grass. The males occasionally show off their strength by walking upright, waving branches, and screaming loudly. The chimpanzee's chief foods include fruits, leaves, seeds, and stems. They also eat ants, bird eggs, fish, and termites. They occasionally kill and eat baboons, bush pigs, and monkeys. Chimpanzees in the wild mate chiefly from August to November, but those in captivity mate more frequently throughout the year. Most females bear their first young at the age of 11 or 12 years. The pregnancy period lasts about 230 days. In most cases, the female gives birth to a single baby. Female chimpanzees generally give birth once every three or four years. The females raise their young almost entirely by themselves. The infants ride under the mother's body, supported by her arm, until they are about 5 months old. Then they ride on the mother's back. Young chimpanzees often chase one another playfully through the trees. Chimpanzees leave their mothers at about 6 years of age. Chimpanzees seldom fight among themselves or become aggressive. The adults spend about an hour each day in a friendly, social activity called grooming. During this period, two or more chimpanzees sit and pick through each other's hair. They remove any dirt, insects, leaves, or burs that they might find. Chimpanzees express themselves vocally by means of barks, grunts, and screams. When they find a large food supply, the animals jump through the trees, hoot loudly, and beat on tree trunks. This activity alerts all other chimpanzees within hearing distance. They also communicate with body postures, facial expressions, and hand gestures. Chimpanzees may greet each other by touching various parts of the other's body or by embracing. Their facial expressions cover a wide variety of emotions, including excitement, fear, and rage. Chimpanzees make and use tools more than any other animal except human beings. For example, they strip the leaves from stems and use the stems as tools to catch termites. They also use leaves to make "sponges" for soaking up water to drink. Biologists believe chimpanzees live from 30 to 38 years in their natural surroundings. They generally live from 40 to 60 years in zoos and research centres. Pygmy chimpanzees are slightly smaller and lighter than other chimpanzees. Adult male pygmy chimpanzees weigh about 45 kilograms and adult females weigh about 35 kilograms. Pygmy chimpanzees live only in a small area of rain forest in Zaire. These chimpanzees are very acrobatic. They jump and dive, hang from branches, and walk on two legs more often than do other chimpanzees. Unlike other chimpanzees, pygmy chimpanzees live in permanent groups of males, females, and infants. The groups may consist of from 5 to 30 individuals. Groups frequently gather to share food. Research on chimpanzees. Chimpanzees and human beings share many physical and social traits. For example, human and chimpanzee polypeptides (compounds that make up proteins) are 99 per cent identical. In addition, human beings and chimpanzees both have similar abilities to solve certain problems. Because of the chimpanzee's many similarities to human beings, scientists frequently use these apes in research. Psychologists use chimpanzees in the study of certain kinds of behaviour, such as communication, intelligence, and learning. In one experiment, chimpanzees were shown an object and then given two objects to feel. By feeling, the chimpanzees learned to identify the object that was identical to the one they had seen. Scientists once believed that only human beings had this ability. Beginning in the 1960's, scientists attempted to teach sign language and other types of language to chimpanzees. Scientists at the University of Nevada, U.S.A., taught more than 160 signs of the American Sign Language to a chimpanzee named Washoe. Washoe learned the names of objects and actions. Some researchers believe that she combined signs in meaningful ways. During the 1970's and 1980's, many other chimpanzees were taught sign language. At the Yerkes Primate Research Center in Atlanta, Georgia, U.S.A., a chimpanzee named Lana learned to use symbols on a computer keyboard to ask for food, companionship, and music.In spite of such accomplishments in teaching chimpanzees to use sign language or symbols, some researchers questioned whether the apes had learned to use language the way people do. These researchers acknowledged that chimpanzees had learned to use "words" (either hand signs or symbols) in appropriate situations. But they doubted that the chimpanzees understood what the signs or symbols represented.In 1980, researchers at the Yerkes Primate Research Center presented evidence that chimpanzees can understand what symbols really mean. Two chimpanzees, named Sherman and Austin, were shown various symbols. The two apes previously had learned to associate each of these symbols with a certain food or tool. After viewing each symbol, the chimpanzees classified it by pressing a "food" or a "tool" symbol on a keyboard. Sherman and Austin consistently put each symbol into the correct category the first time they were shown it. Their responses indicated that they understood what the symbols represented. Later research at Yerkes with a male pygmy chimpanzee named Kanzi has provided further evidence of the ability of chimpanzees to understand language. Kanzi understands more than 150 words produced either by human speech or by electronic speech synthesis. In response to each word, he selects the correct word-symbol on a keyboard and does so without training. The great demand for chimpanzees for research and other purposes has created a serious threat to the animals. Human beings hunt chimpanzees for export to research institutions, circuses, and zoos. In some areas, people hunt chimpanzees for food and for use as household pets. In addition, people have destroyed many of the forests and grassy plains where the animals once lived. Some African countries have established wildlife reserves in order to protect chimpanzees. For example, the Salonga in Zaire is a reserve for pygmy chimpanzees. Conservationists have also proposed the development of captive breeding programmes to stop the threat to wild chimpanzee populations. Scientific Classification. Chimpanzees belong to the anthropoid ape family, Pongidae. They make up the genus Pan. The chimpanzee is P. troglodytes, and the pygmy chimpanzee is P. paniscus.