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经有数百万年的历史，我们的脚和背部仍在两足行走的姿势中艰难斗争，无法轻易承受过长的四肢持续施加的压力。