Chimpanzee


The chimpanzee, also simply known as the chimp, is a species of great ape native to the forests and savannahs of tropical Africa. It has four confirmed subspecies and a fifth proposed one. When its close relative, the bonobo, was more commonly known as the pygmy chimpanzee, this species was often called the common chimpanzee or the robust chimpanzee. The chimpanzee and the bonobo are the only species in the genus Pan.
The chimpanzee is covered in coarse black hair but has a bare face, fingers, toes, palms of the hands, and soles of the feet. It is larger and more robust than the bonobo, weighing for males and for females and standing. Evidence from fossils and DNA sequencing shows that Pan is a sister taxon to the human lineage and is thus humans' closest living relative. The chimpanzee genome contains coding regions for 18,759 proteins which is within ten percent compared to 20,383 proteins for humans.
The chimpanzee lives in groups that range in size from 15 to 150 members, although individuals travel and forage in much smaller groups during the day. The species lives in a strict male-dominated hierarchy, where disputes are generally settled without the need for violence. Nearly all chimpanzee populations have been recorded using tools, modifying sticks, rocks, grass and leaves and using them for hunting and acquiring honey, termites, ants, nuts and water. The species has also been found creating sharpened sticks to spear small mammals. Its gestation period is eight months. The infant is weaned at about three years old but usually maintains a close relationship with its mother for several years more.
The chimpanzee is listed on the IUCN Red List as an endangered species. Between 170,000 and 300,000 individuals are estimated across its range. The biggest threats to the chimpanzee are habitat loss, poaching, and disease. Chimpanzees appear in Western popular culture as stereotyped clown-figures and have featured in entertainments such as chimpanzees' tea parties, circus acts and stage shows. Although chimpanzees have been kept as pets, their strength, aggressiveness, and unpredictability makes them dangerous in this role. Some hundreds have been kept in laboratories for research, especially in the United States. Many experimental attempts have been made to attempt teaching languages such as American Sign Language to chimpanzees, which have been challenged by academics such as Noam Chomsky.

Etymology

The first use of the name chimpanze is recorded in The London Magazine in 1738, glossed as meaning "mockman" in a language of "the Angolans". The spelling chimpanzee is found in a 1758 supplement to Chamber's Cyclopædia. The colloquialism "chimp" was most likely coined some time in the late 1870s.
The genus name Pan derives from the Greek god, while the specific name troglodytes was taken from the Troglodytae, a mythical race of cave-dwellers; it had first been proposed for the genus but a genus of wren took priority.

Taxonomy

The first great ape known to Western science in the 17th century was the "orang-outang", the local Malay name being recorded in Java by the Dutch physician Jacobus Bontius. In 1641, the Dutch anatomist Nicolaes Tulp applied the name to a chimpanzee or bonobo brought to the Netherlands from Angola. Another Dutch anatomist, Peter Camper, dissected specimens from Central Africa and Southeast Asia in the 1770s, noting the differences between the African and Asian apes. The German naturalist Johann Friedrich Blumenbach classified the chimpanzee as Simia troglodytes by 1775. Another German naturalist, Lorenz Oken, coined the genus Pan in 1816. The bonobo was recognised as distinct from the chimpanzee by 1933.
Both chimpanzees and humans are part of the Hominidae, or, hominids, whose members are known as the great apes, are a taxonomic family of primates that includes eight extant species in four genera: Pongo ; Gorilla ; Pan ; and Homo, of which only modern humans remain.

Evolution

Despite a large number of Homo fossil finds, Pan 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, but chimpanzee fossils have now been reported from Kenya. This indicates that both humans and members of the Pan clade were present in the East African Rift Valley during the Middle Pleistocene.
According to studies published in 2017 by researchers at George Washington University, bonobos, along with chimpanzees, split from the human line about 8 million years ago; then bonobos split from the common chimpanzee line about 2 million years ago. Another 2017 genetic study suggests ancient gene flow between 200,000 and 550,000 years ago from the bonobo into the ancestors of central and eastern chimpanzees.

Subspecies and population status

Four subspecies of the chimpanzee have been recognised, with the possibility of a fifth:
A draft version of the chimpanzee genome was published in 2005 and encodes 18,759 proteins,. The DNA sequences of humans and chimpanzees are very similar and the difference in protein number mostly arises from incomplete sequences in the chimpanzee genome. Both species differ by about 35 million single-nucleotide changes, five million insertion/deletion events and various chromosomal rearrangements. Typical human and chimpanzee protein homologs differ in an average of only two amino acids. About 30% of all human proteins are identical in sequence to the corresponding chimpanzee protein. Humans have 23 pairs of chromosomes and other great apes, such as chimpanzees, have 24 pairs of chromosomes. In the human evolutionary lineage, two ancestral ape chromosomes fused at their telomeres, producing human chromosome 2. Another study showed that patterns of DNA methylation, which are a known regulation mechanism for gene expression, differ in the prefrontal cortex of humans versus chimpanzees, and implicated this difference in the evolutionary divergence of the two species.
Image:Humanchimpchromosomes.png|thumb|800px|center|Side by side comparison of human and chimpanzee genomes. M stands for Mitochondrial DNA

Proteome

Studies of the chimpanzee proteome have been considerable since the substantial progress made on the Human proteome atlas after completion of Craig Venter's Human Genome Project at the start of the 21st century. The contains information about the human proteins in cells, tissues, and organs. All the data in the knowledge resource is open access to allow scientists both in academia and industry to freely access the data for exploration of the human proteome. The chimpanzee proteome is described in the paper by Yufan Wang titled "The Chimpanzee Brainnetome Atlas reveals distinct connectivity and gene expression profiles relative to humans."
Forkhead box protein P2 is a protein that, in humans, is encoded by the FOXP2 gene. Three amino acid substitutions distinguish the human FOXP2 protein from that found in mice, while two amino acid substitutions distinguish the human FOXP2 protein from that found in chimpanzees, but only one of these changes is unique to humans. FOXP2 is also required for the proper development of speech and language in humans. In humans, mutations in FOXP2 cause the severe speech and language disorder developmental verbal dyspraxia. Studies of the gene in mice and songbirds indicate that it is necessary for vocal imitation and the related motor learning. Outside the brain, FOXP2 has also been implicated in development of other tissues such as the lung and digestive system.
The human FOXP2 gene differs from that in non-human primates like chimpanzees by the substitution of two amino acids, a threonine to asparagine substitution at position 303 and an asparagine to serine substitution at position 325. One of the two amino acid differences between human and chimpanzees also arose independently in carnivores and bats. Similar FOXP2 proteins can be found in songbirds, fish, and reptiles such as alligators. According to a 2002 study, the FOXP2 gene showed indications of recent positive selection. Some researchers have speculated that positive selection is crucial for the evolution of language in humans. A 2018 analysis of a large sample of globally distributed genomes confirmed there was no evidence of positive selection, suggesting that the original signal of positive selection may be driven by sample composition. Insertion of both human mutations into mice, whose version of FOXP2 otherwise differs from the human and chimpanzee versions in only one additional base pair, causes changes in vocalizations as well as other behavioral changes, such as a reduction in exploratory tendencies, and a decrease in maze learning time. A reduction in dopamine levels and changes in the morphology of certain nerve cells are also observed.
In chimpanzees, FOXP2 differs from the human version by two amino acids. A study in Germany sequenced FOXP2's complementary DNA in chimps and other species to compare it with human complementary DNA in order to find the specific changes in the sequence. FOXP2 was found to be functionally different in humans compared to chimps. Since FOXP2 was also found to have an effect on other genes, its effects on other genes is also being studied. Researchers deduced that there could also be further clinical applications in the direction of these studies in regards to illnesses that show effects on human language ability. While FOXP2 has been proposed to play a critical role in the development of speech and language, this view has been challenged by the fact that the gene is also expressed in other mammals that do not speak. It has also been proposed that the FOXP2 transcription-factor is not so much a hypothetical 'language gene' but rather part of a regulatory machinery related to externalization of speech.