Chimpanzee
| Chimpanzees | ||||||||||||
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 Common Chimpanzee in Cameroon's South Province | ||||||||||||
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| 'Simia troglodytes' Blumenbach, 1775 | ||||||||||||
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Pan troglodytes |
A chimpanzee, often shortened to chimp, is one of the two extant ape species in the genus Pan. The better known chimpanzee is Pan troglodytes, the common chimpanzee, which lives in West and Central Africa. Its cousin, the bonobo (Pan paniscus) is found in the forests of the Democratic Republic of the Congo and was previously called the pygmy chimpanzee. The Congo River forms a boundary between the habitats of the two species.
As apes, chimpanzees are members of the Hominoidea superfamily of primates. The Hominoidea consist of various species of gibbons (or "lesser apes") as well as gorillas, chimpanzees (including bonobos), orangutans, and humans (collectively referred to as the "great apes").
Physical characteristics and behavior
A full grown adult male chimpanzee can weigh from 75 to 155 pounds (35 to 70 kilograms) and stand three to four feet (0.9-1.2 meters) tall, while females usually weigh between 57 and 110 pounds (26 to 50 kilograms) and are two to three and a half feet (0.66 to one meter) tall.
Chimpanzees rarely live past the age of 40 in the wild, but they are known to live to be 60 years old in captivity. Tarzan star Cheeta was still alive in 2006 at the age of 74.
Anatomical differences between common chimpanzees and bonobos are slight. 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 much of the time.
There are marked differences between the two chimp species in sexual and social behavior. Common chimpanzees have an omnivorous diet, a troop hunting culture based on beta males led by a relatively weak alpha male, and highly complex social relationships. Bonobos, on the other hand, have a mostly herbivorous diet and an egalitarian, matriarchal, and sexually promiscuous culture.
Name
Although Africans have had contact with chimpanzees for millennia, the first recorded (Western) contact of humans with chimps was made by Europeans scouting Angola during the seventeenth century. The diary of Portuguese explorer Duarte Pacheco Pereira (1506), preserved in the Portuguese National Archive (Torre do Tombo), is probably the first European document to acknowledge that chimpanzees built their own rudimentary tools.
The first use of the name "chimpanzee," however, did not occur until 1738. The name is derived from an Angolan Bantu 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. Scientists eventually took the 'pan' from in 'chimpanzee' and attributed it to Pan, a rural ancient Greek god of nature. Biologists applied Pan as the genus name of the animal.
History of studies
According to Euro-Arabic myths and legends, chimps as well as other apes existed in ancient times, and fragmented accounts of these stories were relayed by European adventurers. When chimpanzees first began arriving on the European continent, scientists there noted the inaccuracy 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 were presented as a gift to the Prince of Orange in 1640. In 1698, Edward Tyson, an English anatomist dissected a young chimpanzee that had come from Angola and had died soon after arrival. He published his findings in 1699 in the book Organ-Outang, Sive Homo sylvestris, or, The Anatomy of a Pigmie. This was the first scientific publication of the complete anatomy of a chimpanzee (Wood 2006; Montagu 1943). Scientists who initially examined chimpanzees often described them as "pygmies," and noted the animals' distinct similarities to humans.
Darwin's theory of evolution (first published in 1859) spurred scientific interest in chimpanzees, as the anatomical similarity of apes and humans was offered as evidence for the theory of common descent. This lead eventually to numerous studies of the animals in the wild and captivity. The observers of chimpanzees at the time were mainly interested in behavior as it related to that of humans. Much of their attention focused on whether or not the animals had traits that could be considered "good," and the intelligence of chimpanzees was often significantly exaggerated. By the end of the nineteenth century, chimpanzees remained very much a mystery to humans, with very little factual scientific information available.
The twentieth century saw a new age of scientific research into chimpanzee behavior. The most progressive earlier studies on chimpanzees were spearheaded primarily by renowned psychologists Wolfgang Köhler and Robert Yerkes. The men and their colleagues established laboratory studies of chimpanzees that focused specifically on learning about the intellectual abilities of chimpanzees, particularly their capacity for problem-solving. These investigations typically involved basic, practical tests on laboratory chimpanzees, which required a fairly high intellectual capacity, such as how to solve the problem of obtaining an out-of-reach banana. Notably, Yerkes also made extensive observations of chimpanzees in the wild, which added tremendously to the scientific understanding of chimpanzees and their behavior. Yerkes studied chimpanzees until World War II. Köhler published his famous The Mentality of Apes in 1925, which concluded that "chimpanzees manifest intelligent behaviour of the general kind familiar in human beings ... a type of behaviour which counts as specifically human" (Kohler 1925).
Prior to 1960, almost nothing was known about chimpanzee behavior in their natural habitat. In July of that year, Jane Goodall set out to Tanzania's Gombe forest to live among the chimpanzees. Her discovery that chimpanzees make and use tools was groundbreaking, as scientists had previously believed that humans were the only species to do so (Goodall 1986).
Chimpanzees and humans
The genus Pan is generally 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 and gorillas 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 (Wildman 2003).
Some scientists have proposed that troglodytes and paniscus belong with sapiens in the genus Homo, rather than in Pan. One argument for this reclassification 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. A 2003 study considers the importance of where in the genome the differences appear, and highlights differences related to one of the defining qualities of humans: the ability to understand language and to communicate through speech (Clark 2003). 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.
Fossils
While many human fossils have been found, chimpanzee fossils were not 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. These findings indicate that both humans and members of the Pan clade were present in the East African Rift Valley during the Middle Pleistocene (McBrearty 2005).
Endangerment
Some African tribes hunt bonobos for bush meat as a cheap source of food, which has led to a serious decline in the bonobo population.
Attacks on humans
Newspapers have documented several instances of common chimpanzees attacking humans. For instance, in April 2006, more than two dozen chimps escaped from a sanctuary in Sierra Leone and they killed one man and injured several tourists (Osborn 2006; AP 2006). Chimpanzees in Uganda have attacked human children several times, nearly always killing them. Scientists attribute the attacks to the chimps mistaking the children for the Red Columbus Monkey, one of their favorite meals (Wakibi 2004).
The dangers of careless human interactions with chimpanzees are often aggravated by chimpanzees perceiving humans as potential rivals (AP 2005), and the fact that the average chimpanzee has more than five times the upper-body strength of a human male. As a result, virtually any angered chimpanzee can easily overpower and potentially kill even a fully grown man (Argetsinger 2006; AP 2005).
ReferencesISBN links support NWE through referral fees
- Clark, A. G., et al. 2003. Inferring nonneutral evolution from human-chimp-mouse orthologous gene trios. Science 302(5652):1960-3.
- Goodall, J. 1986. The Chimpanzees of Gombe: Patterns of Behavior. Cambridge, MA: Belknap Press. ISBN 0674116496.
- Groves, C., D. E. Wilson, and D. M. Reeder. 2005. Mammal Species of the World (3rd edition). Baltimore, MD: Johns Hopkins Univ. Press.
- Kohler, W. 1925. The Mentality of Apes (2nd edition). London: Routledge & Kegan Paul LTD.
- McBrearty, S., and N. G. Jablonski. 2005. First fossil chimpanzee. Nature 437:105-108.
- Wildman, D.E., M. Uddin, G. Liu, L. I. Grossman, and M. Goodman. 2003. Implications of natural selection in shaping 99.4% nonsynonymous DNA identity between humans and chimpanzees: Enlarging genus Homo. Proceedings of the National Academy of Sciences 100:7181-7188.
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