Chimpanzee
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? Chimpanzees |
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 Common Chimpanzee
in Cameroon's South Province |
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Type Species
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| Simia troglodytes Blumenbach, 1775 |
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| Pan troglodytes Pan paniscus |
Chimpanzee, often abbreviated to chimp, is the common name for two species in the genus Pan. The better known chimpanzee is Pan troglodytes, the Common Chimpanzee, living in West and Central Africa. Its cousin, the Bonobo or Pygmy Chimpanzee (Pan paniscus), is found in the forests of the Democratic Republic of the Congo. The boundary between the two species is formed by the Congo River.
Measurements
A full grown adult male chimpanzee can weigh from 35-70 kg (75-155 pounds) and stand 0.9-1.2 m (3-4 ft) tall, while usually females weigh 26-50 kg (57-110 pounds) and stand 0.66-1 m(2-3.5 ft) tall.
Lifespan
Chimpanzees rarely live past the age of 50 in the wild, but have been known to reach the age of 60 in captivity.
Chimpanzee differences
Anatomical differences between Common and Pygmy Chimpanzees are slight, but in sexual and social behaviour there are marked differences. Common Chimpanzees have an omnivorous diet, a troop hunting culture based on beta males led by a relatively weak alpha, and highly complex social relationships; Bonobos, on the other hand, have a mostly herbivorous diet and an egalitarian, matriarchal, sexually promiscuous culture. 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. Bonobos have longer arms and tend to walk upright most of the time.
History of human interaction
Although Africans have had contact with chimpanzees for millennia, the first recorded (Western) contact of humans with chimps was made by Europeans scouting Angola at some point during the 1600s. The first use of the name "chimpanzee", however, did not occur until 1738. The name is derived from an Angolan Bantu language term "Tshiluba kivili-chimpenze", which is the local name for the animal and translates loosely as "mockman" or possibly just "ape". The colloquialism "chimp" was most likely coined some time in the late 1870s. Science would eventually take the 'pan' occurring in 'chimpanzee' and attribute it to Pan, a rural ancient Greek god of nature. Biologists would apply Pan as the genus name of the animal. Chimps as well as other apes had also been purported to have existed in ancient times, but did so mainly as myths and legends on the edge of Euro-Arabic societal consciousness, mainly through fragmented and sketchy accounts of European adventurers. Apes are mentioned variously by Aristotle, as well as the Bible.
European scientists were bemused when chimpanzees first began arriving on the European continent as a result of these ancient descriptions, which often falsely purported that chimpanzees had horns and hooves. The first of these early trans-continental chimpanzees came from Angola and was presented as a gift to the Prince of Orange in 1640 and was followed by a few of its brethren over the next several years. Scientists who examined these rare specimens were baffled and described these first chimpanzees as "pygmies" of some kind or another, but did manage to note the animals' distinct similarities to humans. The next two decades would see a number of the creatures imported into Europe, mainly acquired by various zoological gardens as entertainment for visitors.
Darwin's theory of evolution (published in 1860), as it did in most life science fields, would spur scientific interest in chimpanzees and led to numerous studies of the animals in the wild and captivity. The observers of chimpanzees at the time were mainly interested in the behaviour as it related to that of humans. However, this was not as strictly and benignly scientific as it sounds, with much attention being focused on whether or not the animals had traits that could be considered 'good' and the intelligence of chimpanzees was often significantly exaggerated. At one point there was even a scheme drawn up to domesticate chimpanzees in order to have them work at various menial tasks (i.e. factory work). By the end of the 1800s there was still very little factual scientific information regarding chimpanzees established. The creatures were still very much a mystery to humans.
The 20th century would see a new age of scientific research into chimpanzee behaviour, generally free from the human egotism and patronizing attitude that had marred the previous era of studies. Prior to 1960, almost nothing was known about chimpanzee behaviour in their natural habitat, but in July of that year, Jane Goodall set out to Tanzania's Gombe forest to live among the chimpanzees. Her discovery of chimpanzees making and using tools was a groundbreaking discovery that altered the very definition of "humanity". Until this discovery, it was believed that humans were the only species to make and use tools. The most progressive earlier studies on chimpanzees were spearheaded primarily by Wolfgang Köhler and Robert Yerkes, both of whom were renowned psychologists. Both men and their colleagues established laboratory studies of chimpanzees focused specifically on learning about the intellectual, particularly the problem-solving abilities, of chimpanzees. This typically involved basic, practical tests where laboratory chimpanzees were required to demonstrate problem-solving abilities in order to solve basic tests which required a fairly high intellectual capacity (such as how to solve the problem of reaching an out of reach banana). Notably, Yerkes also made extensive observations of chimpanzees in the wild which also added tremendously to the scientific understanding of chimpanzees and their behaviour. Yerkes studied chimpanzees until World War II, while Köhler concluded five years of study and published his famous Mentality of Apes in 1925 (which is coincidentally when Yerkes began his analyses), eventually concluding that "chimpanzees manifest intelligent behaviour of the general kind familiar in human beings... a type of behaviour which counts as specifically human" (1925).
Taxonomic relationships
The genus Pan is now considered to be part of the subfamily Homininae to which humans also belong. Biologists believe that the two species of chimpanzees are the closest living evolutionary relatives to humans. It is thought that humans shared a common ancestor with chimpanzees as recently as four to seven million years ago, and that they have about 95 to 99.4 percent of their DNA in common with humans. It has even been proposed that chimpanzees should be placed into the genus Homo, as well. One argument for this is that other species have been reclassified to belong to the same genus on the basis of less genetic similarity than that between humans and chimpanzees. It is very important, however, to consider where the differences in the genome appear. A study published by Clark and Nielsen of Cornell University in the December 2003 issue of the journal Science highlights differences related to one of humankind's defining qualities — the ability to understand language and to communicate through speech. Differences also exist in the genes for smell, in genes that regulate the metabolism of amino acids and in genes that may affect the ability to digest various proteins. The fact that many chimpanzees have been taught to use hundreds of sign language words, and have sometimes passed on this knowledge to their offspring, indicates that "language" may not be such a major divider between humans and other hominids. See the history of hominoid taxonomy for more about the history of the classification of chimpanzees.
Fossils
Many human fossils have been found, but chimpanzee fossils had not been described until 2005. Existing chimpanzee populations in West and Central Africa do not overlap with the major human fossil sites in East Africa. However, chimpanzee fossils have now been reported from Kenya. This would indicate that both humans and members of the Pan clade were present in the East African Rift Valley during the Middle Pleistocene.