Origins of Hominid Bipedalism - Literature review Example

Origins of Hominid Bipedalism Unit Introduction According to Hidemi et al. (21-24), gibbons and Chimpanzees walk on 2 feet, when circumstances force them to do so. The earliest hominid fossils from Tanzania and Ethiopia, dated millions of years, show a considerable adaptation of bipedalism in addition to a hominid dental pattern which has distinct implications. Australopithecus lived for about 3 million years after hominid lineage origin, back 7 million years ago. However, Bipedalism would be hominid primary adaptation, might it have been apelike, apart from walking upright. Hominid bipedalism involves fluid flow to a number of actions, like stand and swing phase. For example, one leg alternates the other, while pushing off with toe power, swinging under the body in a slightly low position. The foot then, first of all makes contact with the heel, and when this is done, the leg remains extended which provides support for the whole body. However, the other leg moves the body forward. Two different hypotheses that attempt to explain the origins of hominid bipedalism are chimpanzee and human bipedalism (Hidemi et al. 21-24). Hidemi et al. (21-24) contends that Chimpanzees cannot move their knee-points to produce a straight leg in stance phase like human beings. Their muscular power has to be exerted in order to support their body. Additionally, their position is constantly fixed which means that, there is no heel strike and toe off in the swing phase. During the swing phase, the gravity center of the body has to shift towards the tendency and supporting leg of the body in order for it to collapse the unsupported side that is countered by muscle contractions on hip side in the stance phase. The thighbone of chimpanzees does not slope inward as the human beings do, meaning that their feet are partly well placed. The animal abductors are also not developed. While walking it is forced to move its upper body from side to side where each step brings the center of gravity to the bearing weight of the leg (Hidemi et al. 21-24). The anatomy of chimpanzee can be compared to walking and tree climbing, while human anatomy to terrestrial adaptation. The anatomy adaptations which underlie human bipedalism are wide and have a lower spine which is curved. It is also short and has an angled femur and broad pelvis, served by large joints and muscular low limbs. The upright human posture is therefore, an expression of early primate evolution trend, which is an erect body. This trend underwent vertical leaping and clinging, through apes and monkeys. However, this transformation from ape to hominid was not between a dog and a horse which might be operated in hominid origins (Hidemi et al 21-24). Hidemi et al. (21-24) contends that, Darwin compared the origin of hominid to human origins and proposed an evolution package, including culture, walking, dentition, intelligence, and upright walking. Hominids were also vegetarians until Homo erectus originated. This kind of evidence is secure to verify their view, because the most efficient bipedalism explanation has evolved, but not changed the evidence. It also explains bipedalism evolution to climbing hypothesis, which includes orthograde and vertical climbing, but no terrestrial locomotion. These two hypotheses suggest that human beings are the only bipeds, with exception of postcranial adaptations, in lower limbs, which explains their unique locomotion. This is indeed true because, for a developed bipedal locomotion, the foot is only part of the body that interfaces the ground directly and strong to deal with pressure and propulsion efficiently. Work Cited Hidemi Ihsida;et al Human Origins and environmental backgrounds. New York : Springer. (2006), Print. Pg (21-24). Evolutionary trends in the genus Homo Introduction Human beings are members of Homo genus, while modern people are from Homo sapiens. They were earlier species of genus. Earlier on it was assumed that human evolution was a sequence of one species to another. This pattern of evolution emerges from fossil records, where modern human beings are the last sort. This evolutionary history is complicated by evidence that our ancestors mated with close related species which added the genetic diversity, documented as Neanderthals and other modern Homo sapiens, Lewin &Foley, Pg (12-16). According to, Lewin &Foley, Pg (12-16), they claim that there are striking resemblances of genus Homo and our ancestors. Australopithecus is adequate reason to place human beings in the same biological tribe. Both genuses walk upright as well as are bipedal. Early Homos were short and light in frame. They were approximately 3 to 5 ft tall and weighed 32 kg. However, large bodies evolution occurred later, where differences between early homos and Australopithecus is evident on the head. Modern human beings have small faces but large heads, as well as small teeth and a jaw compared to Homo’s who had wide jaws, protruding teeth and big heads. Additionally, human became more skilled in developing cultural technologies for survival, while Homos did not. Homo habilis and Homo erectus were found about 1.6 million years ago. Homo habilis were tall and had a large brain, as well as females. Research classifies them both as Homo habilis. The Homo genus evolution coincides with prolonged instability climate in Africa. There was an overall trend of drying and cooling, where, Lewin &Foley, Pg (12-16) claims that in order to adopt to climate changes, humans formed large and capable brains. These human fossils were first discovered by Mary and Leakey in Tanzania at Olduvai Gorge. Similar fossils were also found in Lake Turkana in East Africa in the Great Rift Valley system. Their time and geographical ranges were large. Some other transitional fossils were also found in South Africa in Swartkrans and Sterkfontein caves which were associated with Homo habilis. Lewin &Foley, Pg (12-16), argues that, early transitional brains were 35% large than Australopithecus. It is from Homo habilis that our ancestors started forming brains that were big than that of apes. As the human cranium began to enlarge, his mouth and teeth became small, especially the premolars and molars. Their pattern of teeth indicated that they ate small food and diverse diets. As explained earlier, the size of Homo habilis was large than the early Homos and had long limbs. The modern limb and body size proportions began in Homo erectus evolution. Lewin &Foley, Pg (12-16) explains that the first modern human being was a thin, tall male individual. He is said to have lived around 200.000 years ago and resembled modern Ethiopians. However, he retained few characteristics that are associated with Neanderthals. Homo sapiens and Home erectus resembled the modern man, and believed to have been the first hominid in Africa. Neanderthals ankles, arms and hands resembled those of human species. Work Cited Lewin.R &Foley.R. Principles of Human Evolution. New York : Routlegde. 2004, Print, Pg, 12-16 Read More