Science Fair Project Encyclopedia
The Common Chimpanzee (Pan troglodytes) is a great ape. Colloquially, it is often called the chimpanzee (or simply "chimp"), though technically this term refers to both species in the genus Pan: the Common Chimpanzee and the closely-related Bonobo, or Pygmy Chimpanzee.
Several subspecies of the Common Chimpanzee have been recognized:
- Pan troglodytes troglodytes, Central Common or Black-faced Chimpanzee, in Cameroon, the Central African Republic, Equatorial Guinea, Gabon, the Republic of the Congo, and the Democratic Republic of the Congo;
- Pan troglodytes verus, Western Common or Pale-faced Chimpanzee, in Guinea, Mali, Sierra Leone, Liberia, Côte d'Ivoire, Ghana, and Nigeria;
- Pan troglodytes vellerosus, West Nigerian/East Cameroon Chimpanzee, in Nigeria and Cameroon;
- Pan troglodytes schweinfurthii, Eastern Common or Long-haired Chimpanzee, in the Central African Republic, the Sudan, the Democratic Republic of the Congo, Uganda, Ruanda, Burundi, Tanzania, and Zambia.
Common Chimpanzees are found in the tropical forests and wet savannas of Western and Central Africa. They used to inhabit most of this region, but their habitat has been dramatically reduced in recent years.
Adults in the wild weigh between 40 and 70 kg; males can measure up to 160 cm and females to 130 cm, and both are much stronger than humans. Their bodies are covered by a coarse dark brown hair, except for the face, fingers, toes, palms of the hands and soles of the feet. Both their thumbs and their big toes are opposable, allowing a precision grip. Their gestation period is 8 months. Infants are weaned when they are about 3 years old, but usually maintain a close relationship with their mother for several more years; they reach puberty at the age of 8-10, and their lifespan in captivity is about 50 years.
Their diet is mainly vegetarian, consisting of fruit, leaves, nuts, seeds, tubers, and miscellaneous plantlife supplemented by insects and small prey; there are also instances of organized hunting. In some cases, such as the killing of leopard cubs, this seems to be primarily a protective effort. However, Common Chimpanzees sometimes band together and hunt Red Colobus Monkeys for their meat. Isolated cases of cannibalism have been documented. Chimpanzees have also been known on rare occasions to attack and eat human infants.
Chimpanzee genome project
Human and Common Chimpanzee chromosomes are very similar. The primary difference is that humans have one fewer pair of chromosomes than do other great apes. In the human evolutionary lineage, two ancestral ape chromosomes fused at their telomeres producing human chromosome 2. There are only 9 other major chromosomal differences between Common Chimpanzees and humans: chromosome segment inversions on human chromosomes 1, 4, 5, 9, 12, 15, 16, 17, 18. After the completion of the Human genome project, a Common Chimpanzee genome project was initiated. In December of 2003, a preliminary analysis of 7600 genes shared between the two genomes confirmed that certain genes such as the forkhead-box P2 transcription factor, which is involved in speech development, have undergone rapid evolution in the human lineage. Several genes involved in hearing were also found to have changed rapidly during human evolution, suggesting selection involving human language-related behavior. Differences between individual humans and Common Chimpanzees are about 10 times the typical difference between pairs of humans.
Common Chimpanzees live in communities that typically range from 20 to more than 150 members, but spend most of their time traveling in small parties of just a few individuals. They are both arboreal and terrestrial, spending equal time in the trees and on the ground. Their habitual gait is quadrupedal, using the soles of their feet and resting on their knuckles, but they can walk upright for short distances.
The common chimpanzee lives in a fission-fusion society , and may be found in groups of the following types: all-male, adult females and offspring, bisexual, one female and her offspring, or a single individual. Chimpanzees mate promiscuously. Communities have ranges that overlap with those of other groups. The core of the societies are males who roam around and protect members of the group as well as the hunt. Among males, there is generally a dominance hierarchy. 
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