Animal Database

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Animal Database
Pan
Common Chimp
Common Chimpanzee (Pan troglodytes)
Scientific Classification
Kingdom Animalia
Phylum Chordata
Class Mammalia
Order Primates
Family Hominidae
Genus Pan

Pan or chimpanzees, sometimes colloquially chimps, is a genus of two extant hominid species of apes.

Chimpanzees are members of the family Hominidae, along with gorillas, humans, and orangutans. Chimpanzees split from the human branch of the family about four to six million years ago. Chimpanzees are the closest living relatives to humans, being members of the tribe Hominini (along with extinct species of subtribe Hominina). Chimpanzees are the only known members of the subtribe Panina. The two Pan species split only about one million years ago.

Evolutionary History[]

Evolutionary Relationship[]

The genus Pan is part of the subfamily Homininae, to which humans also belong. These two species are the closest living evolutionary relatives to humans, sharing a common ancestor with humans about four to six million years ago. Research by Mary-Claire King in 1973 found 99% identical DNA between human beings and chimpanzees, although research since has modified that finding to about 94% commonality, with some of the difference occurring in noncoding DNA. Pan troglodytes and Pan paniscus have been proposed to belong with Homo sapiens in the genus Homo, rather than in Pan; e.g., by J. Diamond in his book, wherein he refers to man as The Third Chimpanzee. Among the arguments in favor of this reclassification is that other species have been reclassified to belong to the same genus because of less genetic similarity than that between humans and chimpanzees.

Common Chimpanzee (Blumenbach, 1776) (Pan troglodytes)
 Central Chimpanzee (Blumenbach, 1775) (Pan troglodytes troglodytes)
 Western Chimpanzee (Schwarz, 1934) (Pan troglodytes verus)
 Nigeria-Cameroon Chimpanzee (Pan troglodytes ellioti)
 Eastern Chimpanzee (Giglioli, 1872) (Pan troglodytes schweinfurthii)
Bonobo (Schwarz, 1929) (Pan paniscus)

Fossils[]

Though many human fossils have been found, chimpanzee fossils were not described until 2005. Existing chimpanzee populations in West and Central Africa are separate from the major human fossil sites in East Africa; however, chimpanzee fossils have been reported from Kenya, indicating that both humans and members of the Pan clade were present in the East African Rift Valley during the Middle Pleistocene.

Anatomy and Physiology[]

The male common chimp stands up to 1.7 m (5.6 ft) high and weighs as much as 70 kg (150 lb); the female is somewhat smaller. The common chimp’s long arms, when extended, span one and a half times the body’s height. A chimpanzee's arms are longer than its legs. The bonobo is slightly shorter and thinner than the common chimpanzee but has longer limbs. In trees, both species climb with their long, powerful arms; on the ground, chimpanzees usually knuckle-walk, or walk on all fours, clenching their fists and supporting themselves on the knuckles thereof. Chimpanzee feet are better suited for walking than are those of the orangutan because the chimp has broader soles and shorter toes.

Both the common chimpanzee and bonobo can walk upright on two legs when carrying objects with their hands and arms. The bonobo has proportionately longer upper limbs and more often walks upright than does the common chimpanzee. The coat is dark; the face, fingers, palms of the hands, and soles of the feet, hairless; the chimp, tailless. The exposed skin of the face, hands and feet varies from pink to very dark in both species but is generally lighter in younger individuals, darkening as maturity is reached. A University of Chicago Medical Centre study has found significant genetic differences between chimpanzee populations. A bony shelf over the eyes gives the forehead a receding appearance, and the nose is flat. Although the jaws protrude, the lips are thrust out only when a chimp pouts.

The brain of a chimpanzee has been measured at ~337 cc, ~393 cc, with a general range of 282–500 cc. Human brains, in contrast, have been measured as being three times larger, variously reported volumes include ~1,299 cc, ~1,158 cc, and averages of ~1330 cc.

Chimpanzee testicles are unusually large for their body size, with a combined weight of about 4 oz (110 g) compared to a gorilla's 1 oz (28 g) or a human's 1.5 ounces (43 g). This relatively great size is generally attributed to sperm competition due to the polyandrous nature of chimpanzee mating behavior. Chimpanzees reach puberty at an age of between eight and 10 years and rarely live past age 40 in the wild, but some have lived longer than 60 years in captivity.

Neoteny[]

Bonobos are claimed to be more neotenized than the common chimpanzees because of such features as the proportionately long torso length of the bonobo.

Behavior[]

Anatomical differences between the common chimpanzee and the bonobo are slight, but sexual and social behaviors are markedly different. The common chimpanzee has an omnivorous diet, a troop hunting culture based on beta males led by an alpha male, and highly complex social relationships. The bonobo, on the other hand, has a mostly frugivorous diet and an egalitarian, nonviolent, matriarchal, sexually receptive behavior. Bonobos frequently have sex, sometimes to help prevent and resolve conflicts. Different groups of chimpanzees also have different cultural behavior with preferences for types of tools. The common chimpanzee tends to display greater aggression than does the bonobo. The average, captive chimpanzee sleeps 9.7 hours per day.

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