Because men, compared to male chimps, have such relatively small testicles (large testicles indicate a species where many males mate, one after the other, with the same female), we might guess that promiscuous societies were uncommon in the immediate human past.

If we teach only the findings and products of science - no matter how useful and even inspiring they may be - without communicating its critical method, how can the average person possibly distinguish science from pseudoscience?

A central lesson of science is that to understand complex issues (or even simple ones), we must try to free our minds of dogma and to guarantee the freedom to publish, to contradict, and to experiment. Arguments from authority are unacceptable.

You're an interesting species, an interesting mix. You're capable of such beautiful dreams and such horrible nightmares. You feel so lost, so cut off, so alone, only you're not. See, in all our searching, the only thing we've found that makes the emptiness bearable is each other.

The secrets of evolution are death and time-the deaths of enormous numbers of lifeforms that were imperfectly adapted to the environment; and time for a long succession of small mutations.

Maxwell's Equations have had a greater impact on human history than any ten presidents.

We are a way of the universe knowing itself.