Читать книгу Introducing Anthropology - Laura Pountney - Страница 38

Modern chimpanzees occasionally walk upright, but their skeletons are not adapted for regular walking on two legs. The skeletons of early humans, on the other hand, evolved to support their bodies in an upright position. This means that modern humans have bodies adapted for walking and running long distances on two legs – that is, they are bipedal. Walking upright undoubtedly helped early humans survive in the diverse habitats in which they lived, including forests and grasslands. There are several physical changes that had to occur to make bipedalism possible, among them modifications in foot and knee structure, a curved spine (to absorb shock), broad-shaped hip bones, and a change in the point of attachment between the skull and the neck from a posterior position (as found in other primates) to an inferior position. Bipedalism was an adaptation to the open environments of the African savannah, where the earliest hominins evolved.

bipedalism Walking upright on two feet for the majority of time

One disadvantage of bipedalism is that climbing is much harder, as the feet cannot grip trees. Another disadvantage is the back pain and other skeletal problems that occur as a result of walking upright. Placing all the body’s weight on just two limbs can result in back pain and slipped discs. A further disadvantage of bipedalism was that it resulted in the narrowing of the hips and pelvis, resulting in greater risk in childbirth.