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.
Carl SaganVirtually every major technological advance in the history of the human species - back to the invention of stone tools and the domestication of fire - has been ethically ambiguous.
Carl SaganThe dumbing down of America is evident in the slow decay of substantive content, a kind of celebration of ignorance.
Carl Sagan