Bipedalism

If increase in brain size is not the characteristic that marks out the early evolution of the m hominins, then the alternative is that it is the evolution of upright, bipedal walking. Certainly, there is tentative evidence from Ardipithecus and from Orrorin that there may have been bipedal elements to the earliest hominins, and by the time Australopithecus is present in excess of 4 million years ago. Understanding the evolution of bipedalism is a key problem in early hominin evolution. Human walking is a risky business," British anthropologist John Napier once remarked. Without split-second timing man would fall Hat on his Face; in fact with each step he takes, lie teeters on the edge of catastrophe." Many of the anatomical adaptations-skeletal and muscular-to bipedalism in hominins function to maintain this balance so as to avoid catastrophe.

Although Homo sapiens is not the only primate lo walk on two feel - for instance, chimpanzees and gibbons may use this form of posture in certain environmental circumstances - no other primate does so habitually or with a striding gait. The rarity of habitual bipedalism among primates, and among mammals as a whole, has given rise to the assumption that it is inefficient and therefore unlikely to evolve. As a result, anthropologists have often sought "special" - that is, essentially human - explanations for the origin of bipedalism.

Closely associated with this view is the insidiously seductive recognition that, once an ape is bipedal its hands become "freed" - to carry things, such as food, and to manipulate things, such as tools and weapons. So powerful is this notion that it has often been difficult to escape the assumption that bipedalism evolved in order to free the hands.

Quite apart from its anthropocentric bias in which hominin origins are often interpreted as meaning human origins, the freed-hands hypothesis exemplifies the danger of explaining the origin of a current structure or function in terms of its current utility. The human brain, after all, is unlikely to have evolved so that people might write symphonies or calculate baseball baiting averages. Although it is possible that upright walking evolved because of the advantages of carrying or making things with emancipated hands, other explanations must be explored as well.

Questionnaire:

• Explain about Bipedalism.