Fruit flies are among the most sexually proficient creatures on earth. Their ability to produce a new generation in two weeks has made them the darlings of genetics researchers for nearly a century. Put a male fruit fly into a bottle with a female, and he doesn't waste any time before getting down to business.
So it's a bit bewildering to watch the behavior of certain fruit flies at the National Institutes of Health in Bethesda, Maryland. There, in the laboratories of biologists Ward Odenwald and Shang-Ding Zhang, strange things are happening inside the gallon-size culture jars. In some experiments, the female flies are cowering in groups at the top and bottom of the jars. The males, meanwhile, are having a party -- no, an orgy -- among themselves. With a frenzy usually reserved for chasing females, the males link up end-to-end in big circles or in long, winding rows that look like winged conga lines. As the buzz of the characteristic fruit fly "love song" fills the air, the males repeatedly lurch forward and rub genitals with the next ones in line.
What's going on? Without a wink or a chuckle, Odenwald claims that these male fruit flies are gay -- and that he and Zhang made them that way. The scientists say they transplanted a single gene into the flies that caused them to display homosexual behavior. And that's very interesting, they assert, because a related gene exists in human beings, although there is no evidence yet that the human gene has an effect on sexual preference.
A report of Odenwald and Zhang's findings, to be published this week in Proceedings of the National Academy of Sciences, adds to the mounting evidence that homosexuality has genetic origins, and is sure to produce new fireworks in the contentious debate over what it means to be gay. The two scientists are not foolhardy enough to claim that a single gene can make a person homosexual. But they think their studies may yield important new insights into how genetic makeup, through a complex series of biochemical reactions, influences sexual orientation.
Such work stirs mixed emotions in the gay community. To some extent, gays and lesbians welcome the research because it supports what most of them have long felt: that homosexuality is an innate characteristic, like skin color, rather than a perverse life-style choice, as conservative moralists contend. And if that is true, then gays deserve legal protection similar to the laws that prohibit racial discrimination. "On a political level, genetic research does seem to move the debate along a certain path," says Denny Lee of the Lambda Legal Defense and Education Fund, a gay advocacy group in New York City. "When people understand that being gay or lesbian is an integral characteristic, they are more open-minded about equality for gay Americans."