What are we? To the biologist we are members of a sub-species called Homo sapiens sapiens, which represents a division of the species known as Homo sapiens. The most interesting aspect about our species is that we are able to and can walk upright on our hind legs at all times. This is defiantly not the usual way of getting around for a mammal. The view of evolution is to see it as the product of steady environmental pressure exerted on each species, improving its adaptation to its habitat. This pressure, which has been termed natural selection is responsible for this. Natural selection works on the premise that in any population, no two individuals are exactly alike. Most of the differences between them are inherited from their parents, and are thus capable of being passed along to the next generation. Each generation will be slightly different from the one before it, and a little better adapted to the prevailing condition (Hand, 1993).

Habitually walking around on the hindlimbs, leaving the forelimbs free for other jobs, is an unusual mode of locomotion. Once our ancestors had adopted an upright stance, many things associated with being human became possible, such as fine manipul

Improvement in reproduction is considered one of the benefits of the Bipedals compared to the quadrapeds Bipedalism enables adult to carry food manually to their females and offspring. This mode of provision reduced the need for females to be continuously in foraging both for themselves and their attached offspring as in other competing hominids, thereby offering three important advantages (Strickberger, 1990): (1) a home position which can be considered stable, which helps in providing a more constant social relationships and perhaps closer mother-infant relationships that improve the infants chance of survival, (2) The reduction in injuries to infant because infants no longer were attached to a mother that is continuously mobile and (3) a reduction in the time between each birth by allowing more offspring to be cared for successfully. Thus, the life style introduced by bipedalism, long distance foraging, continuous sexually activity, and their many behaviors probably improved survivorship (Strickberger, 1990).

With more time being spent on the ground, and the animals moving at a faster speed than before, entirely new demands were made upon the foot. In the foot anatomy, when comparing early hominids and humans, there is a difference between the ways in which weight is transmitted along early hominids and human feet. In an early hominid moving bipedally, the weight is carried along the side of the foot, and the push is passed through the middle of the row of toes. In a human, body weight is transmitted along the outside of the foot, then internally across the ball of the foot, and finally push-off is made by the big toe, a much more efficient arrangement for striding (Hunt, 1993). The choice of aligning all of the toes might have been influence by the basically ape-like hominid's tendency to stand and monitor his surroundings. This would have helped develop strong hind feet capable of taking the entire body's weight. The keeping of a permanently upright stance probably came before rather than after the foot's reorganization for fast movement along the ground. Given some reorganization of muscles and bones it can be as economical of energy to stride on two legs as to run on four (Kingdon,1993). Some curvature in the foot bones as shown before, probably indicated that early humans had retained some climbing abilities. This was probably the middle step between primitive and modern features in an evolving foot which would be perfect for bipedalism. In Lucy's feet it has been found that there are subtle but significant differences. For example, the contours are human like but the ankle joints are still chimplike in the flexibility (Kingdon,1993).

ation with the hands, and the carrying of food back to a base camp (Leakey, 1981). This does not suggest that some four million years or so ago primitive hominids evolved upright walking in order to use their hands in refined ways

Some common words found in the essay are:
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Approximate Word count = 1952
Approximate Pages = 8 (250 words per page double spaced)