We swing our arms simply because it would take extra mental and physical effort to keep them still, says Herman Pontzer, a biomechanics researcher at Washington University in st Louis.

根据圣路易斯华盛顿大学生物力学专家Herman Pontzer的说法，我们之所以要摆臂，是因为不这样的话就需要在意识上以及生理上额外花些气力才能使得手臂保持静止。

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