Agnostic suggests that the (gay) AIDS epidemic had the effect of curtailing male homosexual promiscuity. As Pat Buchanan famously wrote, "they have declared war on nature, and now nature is exacting an awful retribution."
Using the GSS, Agnostic looks at the number of partners a respondent has had in the last year. He finds that gay male promiscuity has decreased from the the late eighties through today, presumably as the consequences of AIDS became more firmly established in the public consciousness. This line of reasoning appears sound, although it doesn't mesh with my personal experience. Among all the gay people I know or have known, never has one indicated to me (explicitly, perhaps obviously, but not implicitly, either) that the dangers of sexual promiscuity are an inhibiting factor in his actual sexual behavior.
As the question set on sexual behavior only extends back to 1989, the method precludes any self-reported data prior to the 'discovery' of AIDS (initially referred to as "gay-related immune deficiency" in popular culture and "the 4H disease" by the CDC, as Haitians, homosexuals, hemophiliacs, and heroin users were disproportionately afflicted).
However, the GSS offers an alternative route to tracking gay promiscuity prior to and after the onset of AIDS. I looked at the percentage of gay and bisexual men, aged 45-60 at the time of the survey, who had ten or more male partners in the course of their adult lives. I did this for the time periods 1989-1994 and also 2006-2010. For the early nineties cohort, who were romping around well before AIDS hit the scene, 40.4% of gays reported having ten or more male partners. For the contemporary cohort, the figure is 33.6%.
Given the greater acceptance of homosexuality in the popular culture that has occurred over the two decade period, gays should feel less social pressure for restraint, and so promiscuity should have increased in the contemporary cohort. We see, however, that the opposite has taken place. This corroborates Agnostic's claim.
But we've also witnessed a stagnant, and even declining, level of sexual activity across the American population over time. Men and women are not having more sex or seeking out more partners than they did in the past. If anything, they are having less sex and seeking out fewer partners than they used to. Maybe the decline in promiscuity among gay men simply parallels the decline in promiscuity among the heterosexual majority.
Comparatively, consider the same analysis mentioned above, but this time for lesbian and bisexual women, again aged 45-60 during the periods 1989-1994 and 2006-2008. Among members of the early nineties cohort, 22.9% reported having ten or more female partners in the course of their adult lives. For the contemporary cohort, the figure is only 8.9%. So it looks like lesbians, who have nothing to fear from AIDS, have, like gay men, also become less promiscuous over the last couple of decades than they were before.
GSS variables used: NUMMEN, NUMWOMEN, SEX, AGE(45-60), YEAR(1989-1994)(2006-2010)