Researchers say that by controlling serotonin levels in the brains of laboratory mice, they have been able to influence sexual behavior. But, they warn, it is far too early to conclude that manipulating human brain chemistry can change sexual orientation.
A March 27 LiveScience.com article says that genetically engineered male mice unable to produce their own serotonin exhibited more same-sex courtship behavior, mounting other males and "singing" to them at frequencies too high for the human ear to detect--another part of the mouse mating ritual.
"Serotonin is known to regulate sexual behaviors, such as erection, ejaculation and orgasm, in both mice and men," the article said. "The compound generally dampens sexual activity; for instance, antidepressants that increase the amount of serotonin in the brain sometimes decrease sex drive."
The article said that mice with normal serotonin levels "mounted females first," but that "nearly half" of the mice lacking the brain chemical "clambered onto males before females," and went on to report that when the mice were given injections to enable them to produce serotonin, they then "mounted females more than males." However, if the serotonin levels climbed too high, the result was a reduction in "male-female mounting," the article said.
"An unavoidable question raised by our findings is whether [serotonin] has a role in sexual preference in other animals," the researchers wrote in a paper that was published in science journal Nature on March 24.
Florida State University’s Elaine Hull told LiveScience that the results may have some bearing on the mysteries of human sexuality, but added, "A lot of people are going to be reading more into this than may or may not be warranted." Hull warned that further research was called for, and warned against "jump[ing] to the conclusion that serotonin is the factor that inhibits male-to-male attraction."
Much has been made in the last two decades over the concept of a so-called "gay gene." Though it is unlikely that any single gene will be identified that controls sexual orientation, it is almost certainly the case that genetics plays a role.
Intriguing research carried out in Korea last year shows that there might indeed be a genetic basis for homosexuality, at least in mice--not by the presence of a specific "gay gene," but rather due to the deletion of a gene.
When Korean researchers deleted a gene in laboratory mice relevant to a specific enzyme, fucose mutarotase, what they ended up with were female mice whose sexual behavior focused on other female mice, due to a "masculinization" of their brain structures, reported Neuroscience on July 15, 2010. The female mice shunned sexual contact with male mice, and displayed sexual interest in other females.
"The mutant female mouse underwent a slightly altered developmental program in the brain to resemble the male brain in terms of sexual preference," stated Professor Chankyu Park. Professor Park led the research, which took place at the Korea Advanced Institute of Science and Technology in Daejon, South Korea, reported U.K. newspaper The Daily Telegraph on July 8, 2010.
Similar brain structure differences have been theorized to account for gay and lesbian humans. Scientists suspect that in utero hormone levels play a role in the development of human fetuses that later develop into gay or lesbian adults. Several studies have confirmed a slight, but definite, increase in the incidence of homosexuality in children whose mothers have already given birth to male offspring.
Though changing the hormone balance in the human brain in the same way would probably not lead to a "masculinization" of human neural pathways--the specific hormones that appear to govern human brains and related sexuality are different than in mice--it is possible that an analogous genetic change could have a similar impact of human sexuality. However, a genetically based "cure" (or prevention) for gay humans also seems questionable, since human sexuality could be the result of a confluence of factors.
It is an open question how society might be affected by the eventual discovery of a "gay gene," or even a number of genes interacting in a way that leads to gays and lesbians, rather than heterosexuals, developing. Gay volunteers for a study looking at genetic factors for homosexuality expressed a hope that if a scientific basis in genetics were discovered for homosexuality, the claim--prevalent among religious conservatives--that gays "choose" their sexual orientation would be put to rest once and for all. Were that to be the case, social and legal restrictions on gay equality--such as marriage--might disappear.
However, it is as unlikely that society will change on a dime as it is that a single gene will be discovered that accounts for all or most cases of human homosexuality. An Associated Press Article from Oct. 28. 2007, that reported on the study also carried a quote from Exodus International leader Alan Chambers, who claims to be a former gay man himself. Chambers declared that no matter what science proves about the innate origins of homosexuality, genetics "will never be something that forces people to behave in a certain way." Added Chambers, "We all have the freedom to choose."
The Gay and Lesbian Medical Association’s Joel Ginsberg told the Associated Press that one concern among GLBTs is that any such discovery of a definitive genetic basis for homosexuality might lead to demands for pre-natal testing to screen out--and possibly terminate--fetuses determined likely to grown into gays and lesbians.
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