|Species|| P. troglodytes|
|Subspecies|| P. t. troglodytes|
P. t. verus
P. t. vellerosus
P. t. schweinfurthii
Chimpanzee is the common name for the two extant species in the genus Pan: the common chimpanzee (Pan troglodytes), living primarily in West and Central Africa; and the Bonobo or pygmy chimpanzee (Pan paniscus), found in the forests of the Democratic Republic of the Congo. The Congo River forms the boundary between the two species.
The name "chimpanzee", adopted by Europeans in 1738, derives from the Bantu kivili-chimpenze ("mock man").
A full grown adult male chimpanzee can weigh from 35-70 kilograms (75-155 pounds) and stand 0.9-1.2 meters (3–4 feet) tall, while females usually weigh 26–50 kg (57-110 pounds) and stand 0.66–1 meters (2.0-3.5 feet) tall.
Chimpanzees have both opposable big toes and opposable thumbs. Most primates have nine wrist bones. Humans, chimps and gorillas have eight; two have fused, stabilising the wrist for knuckle-walking.
Chimpanzees rarely live past the age of 50 in the wild, but have been known to reach the age of 60 in captivity, and Tarzan star Cheeta is still alive (as of 2006) at the age of 74.
Chimps travel in small, frequently-changing groups. Larger groups gather around food or an attractive female. Different groups use different tools. Some "fish" for termites with twigs; others crack nuts with rocks or sharpen spears with their teeth to hunt bush-babies.
Males co-operate in hunting and share meat afterwards. Although chimps like meat, it forms only 2% of their diet. Bonobos rarely eat it, and both species prefer fruit. Hunts mainly happen during food shortages or for mating displays.
Angry chimps stand upright, swagger, charge, scream and throw things. Grins usually show fear. Social grooming helps maintain calm and friendly relations. Males from neighboring communities are aggressive with each other.
Anatomical differences between Common and Pygmy Chimpanzees are slight, but in sexual and social behavior there are marked differences. Common Chimpanzees have an omnivorous diet, a troop hunting culture based on beta males led by an alpha male, and highly complex social relationships. Bonobos, on the other hand, have a mostly herbivorous diet and an egalitarian, matriarchal, sexually receptive behavior. 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 more often than the Common Chimpanzee.[Citation Needed]
Among bonobos, females have low-key dominance, priority over eating and solidarity against male aggression. Bonobos use sex in all its permutations to alleviate tension or for appeasement; it’s casual and quick (average 13 seconds) and not necessarily driven by orgasm or reproduction. Anything that arouses the interest of more than one bonobo results in sexual contact. Unlike common chimps, bonobos often have sex face to face. Despite constant sexual activity, reproductive rates are similar to common chimps. Males stay near their mothers all their lives. High-ranking males are usually sons of important females.
Chimps can recognise themselves in a mirror, vocalise and show similar nonverbal communication patterns to humans. Young chimps laugh when playful or being tickled. They appear to express emotions. Individuals identify themselves with distinctive sounds. Chimpanzees don’t have the physiology for speech, but can learn some human language – Washoe learned over 800 ASL signs in the 1960s – though without grammar, syntax or words with variable meaning. Some people compare the usage of ASL by chimpanzees to a parrot speaking due to both animals not really understanding what they are communicating.
Chimp and human brain and CNS anatomy, blood composition and immune response are similar. Many behaviors are similar. However, chimps don’t share history, make long-term plans, or engage in group discussions. The brightest chimp is intellectually duller than a normal human. A form of neuropsin, a protein with a role in learning and memory, believed by evolutionists to have originated less than 5 million years ago, is expressed only in humans.
In tests performed by scientists, chimpanzees were shown to not understand that a human needs to be facing the chimpanzees in order to see them. These results indicate that the intellectual chasm between chimpanzees and humans is larger than previously believed.
Chimps and HIV
HIV may have originated in chimpanzees when they ate monkeys infected with a simian virus, which mutated. This increases the urgency of preserving chimps in their habitat, although commercial logging, bushmeat and the illegal pet trade have put chimps at risk of extinction.
The genus Pan is now considered to be part of the subfamily Hominidae to which humans also belong. Evolutionary 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. Groundbreaking 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 at least some of the difference occurring in "junk" DNA. It has even been proposed that troglodytes and paniscus belong with sapiens in the genus Homo, rather than in Pan. 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. Indeed, cladistic taxonomy, based on both genetic difference and date of likely divergence, is very clear in placing both extant species of Pan in the genus Homo, mainly because the genus Homo takes precedence on account of being coined first. It is very important, however, to consider where the differences in the genome appear.
Most biologists hold the view that chimpanzees and humans share a close common ancestor due to molecular, morphological, physiological, geographical and behavioral similarities. Although in some cases convergent evolution makes for such similarities in distantly related organisms the similarities between humans and chimps include neutral genetic markers that could not be subject to convergent evolution.
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. These macro-phenotypic differences, however, may owe less to physiology than might be assumed given that Homo sapiens developed modern cultural features long after the modern physiological features were in place and indeed competed averagely against other species of Homo with regard to tools, etc. for many millennia. 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.
Many human fossils have been found, but 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. The evolutionist researchers who discovered them asserted: "These fossils, from the Kapthurin Formation, Kenya, show that representatives of Pan were present in the East African Rift Valley during the Middle Pleistocene, where they were contemporary with an extinct species of Homo.".
Notes and references
- Mary-Claire King, Protein polymorphisms in chimpanzee and human evolution, Doctoral dissertation, University of California, Berkeley (1973).
- Humans and Chimps: Close But Not That Close. Scientific American (2006-12-19). Retrieved on 2006-12-20.
- A. Hobolth et al. (2007) Genomic relationships and speciation times of human, chimpanzee, and gorilla inferred from a coalescent hidden Markov model. PLOS Genetics 23:e7
- McBrearty, S. and N. G. Jablonksi (2005), "First fossil chimpanzee," Nature 437(7055):105-8. Entrez PubMed, search on PMID 16136135