Moreover, even though humans have been upright for millions of years, our feet and back continue to struggle with bipedal posture and cannot easily withstand repeated strain imposed by oversize limbs.

• 此外，尽管人类直立行走已达百万年之久，我们的脚和背总是很费劲地保持两脚站立的姿势、难以经受过大的身材带来的反复巨大压力。