Last updated on: 3/19/2008 12:56:00 PM PST
Could a Germ Cause Homosexuality?


General Reference (not clearly pro or con)
Caleb Crain, PhD, freelance journalist, in a 1999 article for Out magazine titled "Did a Germ Make You Gay?" wrote:

"Paul W. Ewald, a biology professor at Amherst College in Massachusetts, and Gregory Cochran, an independent physicist in Albuquerque, New Mexico, have a new theory about homosexuality: You catch it. Right now their theory is just that — a theory...

According to the best available estimates... 3 to 4 percent of men and 1 to 2 percent of women in the United States are exclusively homosexual. That's a lot of homosexuals. Too many, Cochran and Ewald believe, for the condition to be genetic. No one has found a virus or a bacterium for homosexuality. (So far no one seems to have looked.) But recently, a slew of ailments that were long thought to be caused by stress, high living, or genetic bad luck have instead been pinned on microbes...

Ewald and Cochran boldly predict that we will eventually find germs for every condition that carries a high fitness cost, strikes more often than a random mutation (that is, more than one person in 50,000), and cannot be explained by a new environmental hazard such as pesticides or cigarettes."

1999 - Caleb Crain, PhD 

Judith Hooper, freelance journalist, in a Feb. 1999 article for Atlantic Monthly titled "A New Germ Theory," wrote:

"Genetic traits that may be unfavorable to an organism's survival or reproduction do not persist in the gene pool for very long. Natural selection, by its very definition, weeds them out in short order. By this logic, any inherited disease or trait that has a serious impact on fitness must fade over time, because the genes that spell out that disease or trait will be passed on to fewer and fewer individuals in future generations...

The best estimates of the fitness cost of homosexuality hover around 80 percent: in other words, gay men (in modern times, at least) have only 20 percent as many offspring as heterosexuals have. Simple math shows how quickly an evolutionarily disadvantageous trait like this should dwindle, if it is a simple genetic phenomenon.

No one, of course, has ever isolated a bacterium or a virus responsible for sexual orientation, and speculations about the manner in which such an agent would be transmitted can be nothing more than that. But [Paul] Ewald and [Gregory] Cochran contend that the severe 'fitness hit' of homosexuality is a red flag that should not be ignored, and that an infectious process should at least be explored."

Feb. 1999 - Judith B. Hooper 



PRO (yes)

Paul Ewald, PhD, Director of the Program in Evolutionary Medicine at the University of Louisville, in an Aug. 1999 interview for Out magazine, stated:

"The argument about infectious causation of homosexuality is a feasible hypothesis and should be treated as such."

Aug. 1999 - Paul W. Ewald, PhD 



Gregory M. Cochran, PhD, Adjunct Professor of Anthropology at the University of Utah, wrote in a 1992 web essay "Ewald on the New Germ Theory":

"Homosexuality [is] biological disadvantageous, culturally consequential. Old and common enough to probably have an infectious origin. The low twin concordance (and neoDarwinism) makes strongly genetic explanations unlikely...

I think that not too long after we determine the etiology of homosexuality, we'll be able to prevent it, and almost all parents will."

1992 - Gregory Cochran, PhD 



J. Michael Bailey, PhD, Professor of Psychology at Northwestern University, in an Aug. 26, 2002 interview with the United Press International, stated:

"Greg Cochran has convinced me that this theory [of a gay germ] is at least tenable, which puts it way above competing theories. Most of the evolutionary speculation about homosexuality has been quite lame, even speculation by respected thinkers. The persistence of homosexuality despite the fact that gay and lesbian people clearly reproduce less often than straight people is perhaps the most striking paradox in all of human evolution."

Aug. 26, 2002 - J. Michael Bailey, PhD 



CON (no)

Dean H. Hamer, PhD, former Chief of the Section on Gene Structure and Regulation at the Laboratory of Biochemistry at the National Cancer Institute, stated in an Aug. 1999 interview for Out magazine:

"I think it's a very interesting idea. The idea that homosexuality resulted from overprotective mothers was also an interesting idea. But when it was tested, it turned out to be completely untrue. Whether [Ewald and Cochran's theory is] true or false is an experimental question and needs to be answered by observation and by experimentation, not by chitchat."

Aug. 1999 - Dean H. Hamer, PhD 



William Byne, MD, PhD, Director of the Laboratory of Neuroanatomy and Morphometrics at Mount Sinai School of Medicine, in an Aug. 1999 interview for Out magazine, stated:

"It's hard for most people to entertain the idea that homosexuality might be a natural variant of human sexual behavior. [Cochran and Ewald] are guilty of pathologizing homosexuality."

Aug. 1999 - William M. Byne, MD, PhD 



James T. Martin, MS, PhD, of the College of Osteopathic Medicine of the Pacific, wrote in a May 1999 letter to the editor in response to the article "A New Germ Theory" from the Feb. 1999 Atlantic Monthly:

"Paul Ewald and Gregory Cochran are certainly correct that fitness costs should be factored into all theories of etiology. What is apparently missing from their simplistic analysis is an understanding of adaptation. The environment in which we live now is very different from the one for which we are evolutionarily adapted, and coping with this environment produces great stresses on organ systems...

A more troubling aspect of Ewald's fitness blitzkrieg is the idea that homosexuality is a result of an infectious agent acting during development. Apparently ignored here are the contributions to evolutionary biology of W. D. Hamilton, E. O. [Edward] Wilson, and R. L. [Robert] Trivers, which provide a much better basis for understanding homosexuality, as a phenomenon of inclusive fitness."

May 1999 - James T. Martin, MS, PhD