Ah, sex.  Freud, and many others, felt that sex was the most significant motivator in human life.  It's interesting that you die without food in a few weeks, without water in a few days, and without air in a few minutes.  You will not die without sex (although you may want to).  And yet, in the biological scheme of things, it is reproduction, not individual survival, that counts.  Animals, including us humans, are supplied with powerful instincts that urge them on to having sex, sometimes at the cost of their own lives! The science of sex only dates back about a century. The first major figure is Richard von Krafft-Ebing, who studied sexual "deviations" in the late 1800's.  He popularized the term homosexuality, and fought to decriminalize it.  On the negative side, he was convinced that women who have strong sexual appetites are quite abnormal. Another early figure is Henry Havelock Ellis, who looked into the social aspects of sexuality in the late 1800's and early 1900's.  He is a hero to both the homosexual community and the feminist movement.  He insisted that homosexuality was both inborn and irreversible, a notion some people still can't seem to accept.  And he had the audacity to suggest that women have the similar sexual needs and desires as men!  Margaret Sanger referred to him as "Olympian!" Beginning in the 1930's, a Harvard entomologist name Alfred Kinsey started to systematically collect data on sexual practices.  He found, for example, that 90% of the men he interviewed had masturbated, that 85% had engaged in premarital intercourse, and that 60% had engaged in oral sex.  This of course shocked a conservative American public, who had (like their Victorian predecessors) been in heavy denial about this sort of thing! His statistics on homosexuality were even more shocking:  He found that 37% of men had had at least one homosexual interaction resulting in orgasm, that 10% of men had been exclusively homosexual for the last three years, and that 4% of men had been exclusively homosexual their entire lives.  The general direction of these statistics has been supported again and again since then.