科学家们表示，史前人类的饮食可能需要更多咀嚼齿。

Scientists say the diet of prehistoric humans probably required more chewing teeth.

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我们不应该为那些史前人类的复杂思想而感到惊讶，他们毕竟是我们的曾曾祖父。

We shouldn't be surprised by the sophistication of these people's thinking: they were our great-great-grandparents after all, "he says."

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科学家们在发现了400，000年前人类的残骸后，不得不重新书写现代人类的进化史。

Scientists could be forced to re-write the history of the evolution of modern man after the discovery of 400, 000-year-old human remains.

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Aristotle, over 2000 years ago, "Happiness is the meaning and purpose of life, " the whole aim and end of human existence."

二千多年前的亚里斯多德，“快乐是人生的意义和目的，人类存在的最终目标“

哈佛公开课 - 幸福课课程节选

There are lots of people who have pointed out to us that before a certain period, there was no such thing as man, and in a variety of quite real senses, after a certain moment in the history of culture, there is also no such thing as man.

很多人向我们指出,在某一特定时间点前是没有人类的，而且在真实意义上，在文化史中的某一特定时刻后，人类也不存在。

耶鲁公开课 - 文学理论导论课程节选

A human cell shown here on the opposite side has these formed organelles that I talked about a minute ago, mitochondria, Golgi, endoplasmic reticulum, nucleus.

另一边展示的是人类细胞,它带有我一分钟前讲过的成形的细胞器,线粒体,高尔基体,内质网,细胞核

耶鲁公开课 - 生物医学工程探索课程节选