![]() Subsequent evolution in brain size ( 3) and cognition as well as advancements in tools and other material culture ( 4, 5) have reduced our strict dependence on muscular strength for survival and fitness. Whereas chimpanzees are proficient tree climbers and arborealists ( 1), our hominin ancestors gave up a reliance on the forest canopy after the emergence of the genus Homo ( 2). Modern humans-with some exceptions-are often characterized as a weak and unathletic species compared with our closest living relatives, the chimpanzees. We propose that the hominin lineage experienced a decline in maximum dynamic force and power output during the past 7–8 million years in response to selection for repetitive, low-cost contractile behavior. Thus, the superior mass-specific muscular performance of chimpanzees does not stem from differences in isometric force-generating capabilities or maximum shortening velocities-as has long been suggested-but rather is due in part to differences in MHC isoform content and fiber length. Computer simulations of species-specific whole-muscle models indicate that maximum dynamic force and power output is 1.35 times higher in a chimpanzee muscle than a human muscle of similar size. Unlike humans, chimpanzee muscle is composed of ∼67% fast-twitch fibers (MHC IIa+IId). Here, we show that chimpanzee muscle is similar to human muscle in its single-fiber contractile properties, but exhibits a much higher fraction of MHC II isoforms. Hypotheses for the muscular basis of this performance differential have included greater isometric force-generating capabilities, faster maximum shortening velocities, and/or a difference in myosin heavy chain (MHC) isoform content in chimpanzee relative to human skeletal muscle. A mix of anecdotal and more controlled studies provides some support for this view however, a critical review of available data suggests that chimpanzee mass-specific muscular performance is a more modest 1.5 times greater than humans on average. Chimpanzees may also help with the dispersal of seeds of certain plants, through transportation, or by eating the fruit.Since at least the 1920s, it has been reported that common chimpanzees ( Pan troglodytes) differ from humans in being capable of exceptional feats of “super strength,” both in the wild and in captive environments. They have a large impact on the Red colobus monkey, bush pigs, and baboons by predating them. Overall, currently, Common chimpanzees are classified as Endangered (EN) on the IUCN Red List and their numbers today are decreasing.Ĭhimpanzees, as predators, may have a role in controlling the populations of their prey. Four subspecies of the Common chimpanzee have been recognized and current estimates for each subspecies are following: Nigeria-Cameroon chimpanzee - fewer than 6,000-9,000, Eastern chimpanzee - 181,000-256,000, Central chimpanzee - 140,000, Western chimpanzee - 18,000-65,000. Adults are killed for bushmeat so that the poacher can take young chimpanzees to sell as pets.Īccording to IUCN Red List, as of 2003, the total Common chimpanzee population size was estimated to be 172,700–299,700 apes. The illegal exotic pet trade provides incentives to poachers to hunt chimpanzees. Its biggest threats come from habitat destruction, disease, and poaching. The chimpanzee is on the IUCN list as being endangered in its natural habitat. Females at 13 years of age are thought to be ready to reproduce, while males reach sexual maturity at about 16 years old. ![]() Playing with other young chimpanzees allows them to practice grooming as well as wrestling skills. They learn survival skills by observing their mother to find out what to eat, how to build nests, and make tools. They are weaned at the age of 4 to 6 years. At two years old, young chimpanzees are able to sit independently and move about. The mother and her baby remain in continual contact during their first year. Gestation lasts for about 8 months and then a single infant is born. There is no clear breeding season for chimpanzees, and mating can take place at any time of the year, with babies born in any season. ![]() In addition, females sometimes leave their community and mate with males from neighboring communities. A male and female can form a consortship and mate outside their community. Chimpanzees have a polygynandrous (promiscuous) mating system in which males and females mate with several mates in their community. ![]()
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