Sexology is the study of human behaviours, functions and interests around their sexuality. Although manuals and books describing sex have been around since early civilization (see the Kama Sutra or the Ananga Rana for example), the study by Parent-Duchatelet on Prostitution in the City of Paris published a year after his death in 1837 is regarded as the first scientific study on human sexuality. In 1886 in Germany, Richard Krafft-Ebing published Psychopathia Sexualis which established the science of Sexology and his work was mirrored by Havelock Ellis in England. In these works, terms and concepts we are familiar with were first coined (though of course they had existed, just not understood in a scientific way), things like homosexuality, sadism and masochism for instance. Ellis was very understanding of gay relationships and did not characterise them as immoral or as a mental illness - as Krafft-Ebing had done.
Ellis also understood that transgender did not necessarily equate to and was distinct from homosexuality. In 1908 in Germany, the first journal in the field was produced, which contained articles by Sigmund Freud and Alfred Adler. Freud's theories have largely been dismissed but his work, and others in Germany, made that country the leader in the study up until 1933 when within months of coming to power, the Nazi's banned the works of scientists like Magnus Hirschfeld - who was an outspoken advocate for sexual minorities and an advocate for gay and transgender rights. His Institut fur Sexualwissenschaft library of 20,000 volumes, 35,000 photos were burned, the institute shut down and Hirschfeld exiled to France.
After WW2, work in this field was carried on in the USA and large studies of sexual behaviour were carried out. Alfred Kinsey founded the Institute for Sex Research at Indiana University in 1947 and later in 1966 Masters and Johnson published Human Sexual Response, and later Human Sexual Inadequacy which pioneered the diagnosis and treatment of sexual disorders and dysfunctions. Want to hear a skeptical look at Bestiality? Come along to the Banshee Labyrinth tonight at 7:20 to hear James give his slightly irreverent view.