这个谜题的答案在于早期光合生命形式的新陈代谢活动，这种活动缓慢但一定改变了地球大气的化学成分。

The answer to this riddle lies in the metabolic activity of early photosynthetic life-forms that slowly but surely transformed the chemical composition of Earth's atmosphere.

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他们也测量了老鼠的代谢活动。

They also tested metabolic function in mice.

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使用手机会迫使大脑中的耳部区域的代谢活动发生变化。

Talking on a cell phone pressed to the ear changes activity in the brain.

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Different amount of metabolic activity because one has a greater volume of cytoplasm than the other, for example, so these are exactly the right kinds of ideas.

大小不同,代谢活动的总量就会不同,可能因为一个细胞的胞质比另一个体积大,以上这些观点都是非常正确的

耶鲁公开课 - 生物医学工程探索课程节选

As we'll discuss in the class, and most of you probably know this, your body weight is a function of how many calories you take in and how many calories you burn off through metabolic processes but also physical activity.

我们将会讲到,而且你们中的大部分人可能也知道,你的体重随着卡路里的摄取量,和代谢中的消耗量而变化,还跟肢体活动有关

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选