Читать книгу Anthropology For Dummies - Cameron M. Smith - Страница 92

Although many primates occasionally stand up to walk on two feet (and one gorilla in West Africa has even been observed to use a walking stick to cross a swampy patch of ground), they do so on occasion rather than habitually. Of the living primates, only Homo sapiens sapiens walks on two legs; I discuss why that’s a fascinating question in Chapter 6. For the moment, take a look at the main anatomical characteristics of bipedal primates:

 Relatively long, strong legs

 An S-shaped spinal column that acts as a spring to absorb stresses

 A wide pelvis that keeps the thighs somewhat apart, helping balance

 A parallel big toe lined up with the rest of the toes (rather than the divergent big toe used by other primates to grasp tree limbs)

 Thighs that angle inward toward the knees and down from the pelvis, also assisting balance

 Lateral and transverse arches built into the foot so that we aren’t flat-footed but supported by three main points of contact (the heel and under the big and small toes) in a stable, tripod-like structure

Humans aren’t the only species ever to evolve bipedalism; kangaroos are another, and, given enough time and the right circumstances, bipedalism could easily evolve again, perhaps in the African meerkats, who spend a lot of time standing on their hind legs. But among the primates, humans are the only living habitual bipeds. As Chapter 6 shows, though, other primates did evolve bipedalism and used to be quite numerous between about six million and two million years ago.