Believe it or not, sometimes I check the "Asexuality" page on Wikipedia to see if there's anything new there. This is a very slow day, so I did exactly that. And there's a LOT more information on research now, including more things I've never heard of before. This intrigued me the most:
A 1977 paper entitled Asexual and Autoerotic Women: Two Invisible Groups, by Myra T. Johnson, may be the first explicitely devoted to asexuality in humans. Johnson defines asexuals as those men and women "who, regardless of physical or emotional condition, actual sexual history, and marital status or ideological orientation, seem to prefer not to engage in sexual activity." She contrasts autoerotic women with asexual women: "The asexual woman...has no sexual desires at all [but] the autoerotic woman...recognizes such desires but prefers to satisfy them alone." Johnson's evidence is mostly letters to the editor found in women's magazines written by asexual/autoerotic women. She portrays them as invisible, "oppressed by a consensus that they are nonexistent," and left behind by both the sexual revolution and feminist movement. Society either ignores or denies their existence, or insists they must be ascetic for religious reasons, neurotic, or asexual for political reasons.
Cool, huh? It's in a book called "The Sexually Oppressed", which I'm actually buying off Amazon.com right now. The book's only $6.50 with shipping, which seems like a fairly good deal for an out-of-print volume from 1977. A small price to pay for our edification, don't you think?