Chimpanzee
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| Pan troglodytes Blumenbach, 1775 |
The chimpanzee (or chimp) is one of two species of great apes; Pan troglodytes (the common chimpanzee) and Pan paniscus (the Bonobo, formerly called pygmy chimpanzee). Biologists believe that chimpanzees are our closest evolutionary relatives; they branched off from our latest common ancestor as recently as 4 to 7 million years ago, and we share 98-99.4% of our DNA with them, which prompted Jared Diamond to use the term "the third chimpanzee" for our own species. Some believe that assigning chimpanzees to a different genus or even family than humans, a taxonomic division that goes back to Linnaeus and that he later regretted, is not justified on biological grounds, and in fact amounts to an instance of anthropocentrism.
Pan paniscus was not recognized as an independent species until quite recently, and in common language the designation "chimpanzee" often applies to both apes. Primatologists prefer to reserve the name "chimpanzee" for Pan troglodytes. Anatomical differences between the two species are slight, but in sexual and social behaviour there are some marked distinctions. For example, P. troglodytes has a troop hunting culture based on beta males led by a relatively weak alpha, an omnivorous diet, and a complex culture with long bonds. P. paniscus chimps, on the other hand, are sexually promiscuous.
Several subspecies of chimpanzee have been recognized:
- Pan troglodytes troglodytes, Central Common or Black-faced Chimpanzee
- Pan troglodytes schweinfurthii, Eastern Common or Long-haired Chimpanzee
- Pan troglodytes verus, Western Common or Pale-faced Chimpanzee
- Pan troglodytes vellerosus, West Nigerian/East Cameroon Chimpanzee
Basic facts
Chimpanzees are found in the tropical forests and wet savannahs of Western and Central Africa. They used to inhabit most of this region, but their habitat has been dramatically reduced in recent years.
Adult chimpanzees in the wild can measure up to 130 cm (females) or 160 cm (males), and adults weigh between 40 and 70 kg, but are much stronger than humans. Their body is 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. The 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 years more. Puberty is reached at the age of 8-10, and their lifespan in captivity is about 50 years.
Chimpanzees live in groups called communities that range from about 20 to more than 150 members, consisting of several males, females and juveniles. However, most of the time they travel around 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 a short distance.
Their diet is mainly vegetarian (fruit, leaves, nuts, seeds, tubers...), supplemented by insects and small prey; there are instances of hunting. In some cases—such as killing leopard cubs—this hunting seems to be primarily a protective effort by the chimpanzees, rather than being motivated by hunger. However, chimpanzees sometimes band together and hunt Red Colobus Monkeys for meat; this shows that they are capable of group hunting like humans, and have a taste for flesh. Isolated cases of cannibalism have been documented.
Chimp genome project
Human and chimp chromosomes are very similar. The major difference is that humans have two less 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 chimps 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 chimp genome project was initiated. In December of 2003 a preliminary analysis of 7600 genes shared between the chimp and human genomes confirmed that certain genes such as the forkhead-box P2 transcription factor have undergone rapid evolution in the human lineage. This gene is involved in human speech development. Several genes involved in hearing were also found to have changed rapidly during human evolution, suggesting selection involving human language-related behavior. Human-chimp DNA differences are about 10 times the typical difference between pairs of humans.
- Distribution
- Social life
- Sexual behaviour
- Cognitive skills:
- Language
- Tool use
See Also
- Jane Goodall
- List of historical apes (includes chimpanzees)