Chimpanzees, gorillas, and orangutans are all considered great apes. Of the three, chimpanzees are the most closely related to humans. Chimpanzees and humans share 98 percent of the same genetic makeup.

In addition, the two groups share many social and psychological traits. Researchers have documented chimpanzees making and using tools, expressing complex emotions, forming bonds and friendships, and communicating using sign language.

An average chimpanzee stands 5 feet (1.5 meters) tall and weighs about 150 pounds (68 kilograms). Since its arms are longer than its legs, a chimpanzee walks on the ground using the soles of its feet and the knuckles of its hands.

Most of its body is covered with long, black hair. A chimpanzee’s hairless face can range in color from almost white to almost black. The hair around a chimpanzee’s face grays with age, and older chimpanzees often become bald.

Highly social mammals, chimpanzees live in communities made up of 30 to 60 members. During the day, the animals often travel on the ground. At night, they stay in nests they build in treetops.

A chimpanzee’s diet consists mainly of fruit, but they also eat insects, leaves, flowers, bark, seeds, tree resin, eggs, and meat. At times, chimpanzees band together to hunt animals such as antelopes and monkeys.

Mating between male and female chimpanzees takes place anytime during the year. Unlike many other animal species, female chimpanzees do not have to mate with the dominant male in their group. Instead, females often mate with males of their choosing.

After a gestation (pregnancy) period of 230 to 240 days, a female chimpanzee gives birth to a single infant. During the course of her life, an average female chimpanzee will give birth to fewer than five infants. Bonds between mothers and infants are very strong, and some last a lifetime.

Habitat and current distribution

A few centuries ago, several million chimpanzees existed in the equatorial regions of Africa. They inhabited a range of ecosystems, from dense forests to open savannas.

Now, estimates vary, but it is thought that there are between 200,000 and 225,000 chimpanzees in the wild, and many believe these estimates are high. Only 10 present-day African nations have chimpanzee populations above 1,000.

About 5,000 chimpanzees exist in captivity worldwide. Over one-half of these are used as subjects in medical research. The rest are zoo exhibits, entertainment props, and private pets.

History and conservation measures

Habitat destruction, disease, and expanding human populations have led to the decline in the number of chimpanzees. Mining has destroyed the chimpanzee habitat in the diamond districts of Sierra Leone and the iron districts of Liberia.

The cutting of forests for timber has destroyed the animals’ habitat in Uganda. And the conversion of forests into agricultural land has threatened chimpanzees in Rwanda and Burundi.

Certain laws prohibit the hunting and sale of chimpanzees, but these laws are not enforced. Many chimpanzees are caught and traded illegally. For each chimpanzee shipped overseas, ten die during transport due to mistreatment and malnutrition.

Two sanctuaries exist in Gambia and Zambia for orphaned chimpanzees and those seized from illegal traders. Most African nations have passed laws and have set aside areas to protect chimpanzees. However, as human populations in Africa continue to grow, many of these reserves may be used to fill human needs.

In 2003, a group of scientists and conservationists called for an upgrade in the status of chimpanzees from endangered to critically endangered. Data coming from Gabon and the Republic of Congo, where most of the world’s chimpanzees live, reveals that the ape population there has decreased by half between 1983 and 2000.

The reasons for the decline were continued hunting and outbreaks among chimpanzees and gorillas of the Ebola virus, a very deadly and contagious virus that was discovered in Africa during the 1970s and afflicts humans as well.

The group of scientists warned that chimpanzees and gorillas are in greater jeopardy of extinction than had been formerly realized. They called for greater enforcement of laws against hunting and capturing chimpanzees and an increased focus on research of the Ebola virus in primates.