Lucy's Pelvis Vs. Chimpanzee

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Charles Darwin founded the theory of evolution by natural selection, which according to this principle defines; biological characteristics enhance survival increase in frequency from generation to generation (Larsen et al. 22). These individuals are inclined to produce more sustainable offspring to pass their genes to, meaning that some individuals are more reproductively fruitful than others. Natural selection requires variation in a species, which can result by gene flow, mutation, or genetic drift & also involves environmental stresses such as climate change. These result as the evolutionary means of how certain traits can be selected. Eventually, traits that give individuals certain advantages, such as bipedalism in hominids, will be selected …show more content…

The short, broad modern human pelvis has evolved from a taller, narrower pelvis of the chimpanzee or gorilla. Lucy's pelvis, the first Australopithecus Afarensis skeleton to be recovered, differed from a chimpanzee’s pelvis. In the structure of the hipbones, a chimpanzee’s are facing straight forward, whereas in Lucy’s the pelvis was much more human like as it was small & wide but it required the modifications that enable today’s hominids to walk with a striding posture (Becoming Human: Part 1). Natural selection created a human pelvis giving a saddle like support system for bipedal locomotion. The iliac bones construct the saddle feature around the human waist, while in chimpanzees the bones lie flatly posteriorly. This assisted chimpanzees because important climbing muscles attach to the iliac blade. In humans the curved iliac bones provide stability & support for the weight of standing upright & walking; this shape allows the attachment of the big gluteal muscles which are also used to support upright posture …show more content…

The human foot is transverse & arched, while the chimpanzee foot lacks these arches due to the fact that their feet are flat. This distinct feature gives human’s increased leverage as the body pushes forward & serves as a shock absorber when the feet make contact with the ground during walking & running (Larsen et al. 232). Also, humans have fully extendable legs due to a lockable knee joint & a natural knock-kneed stance which differs from the chimpanzee bow-legged stance. Additionally, the human femur attaches at an inward angle to the pelvis which makes the knees lie underneath the center of gravity, the pelvis. This inward angle of the femur provides stability in standing, walking & running (Lecture). As the climate was drying in East Africa, sources of food, such as fruit trees, were growing farther apart & hominids would have to walk farther & farther to gather food (Becoming Human: Part 1). As a result of this anatomical variance, humans can stand upright for long periods of time without much energy outlay. Whereas in quadrupeds, upright posture takes up much more energy because their legs need to stay flexed, requiring the use of more muscles than a human to keep their balance, which is where the bow-legged stance comes into

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