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。

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This is a robotic walking machine, bipedal, about 4 meters tall.

这是一个行走机器人，双足，高约4米。

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One of these gene machines, a social and bipedal ape, began to imitate.

这些“基因机器”其中的一个，一个群居的两足人猿开始了模仿。

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The second camp argues that bipedal dinosaurs with partial wings learnt to use them to fly.

ECONOMIST: Birds that don't fly may be using their wings to run uphill

And a seven-million-year-old hominid from Chad, known as Sahelanthropus tchadensis and nicknamed Toumai, may also have been bipedal.

BBC: NEWS | Science/Nature | Scientists unearth early skeleton

This makes the few known bipedal snakes in the fossil record hugely significant, because they could hold the clues that settle this particular debate.

BBC: Studying how snakes got legless