To: Solon who wrote (31619 ) 12/9/2012 7:47:05 PM From: longnshort Read Replies (2) | Respond to Gay Gene or Gay Germ?--Is Homosexuality an Infection?What Cochran suspected about homosexuality, he and his colleague now believe to be true for a large number of conditions—namely, that microbes, not genes, are responsible for them. Ewald and Cochran’s innovation is to consider disease from the perspective of human evolution. If your mother is obsessed with knowing when you are going to give her some grandchildren, then you are more or less familiar with the traditional perspective of human evolution: You were put on this earth to reproduce. Anything that gets in the way of reproduction is a problem that you better be prepared to explain. To judge the size of such a problem, evolutionary biologists assess its "fitness cost"—that is, the damage it does to your chances of procreating. Genes with a substantial fitness cost do appear from time to time. Every so often a cell makes a mistake while copying its DNA—a mistake known as a random mutation—and this mutation may give rise to a gene harmful to the person carrying it. But in such a case, according to evolutionary theory, the new disease-causing gene would vanish after a hundred generations or so, gradually but inexorably, because damaged organisms reproduce less often and less prolifically than healthy ones. (There is an exception: Some disease-causing genes simultaneously provide a protective benefit—such as the gene for sickle-cell anemia, which also happens to ward off malaria.) The higher its fitness cost, the faster a gene disappears. The math is unforgiving. If a genetic trait has a fitness cost of just 1 percent, it will sink to the very low rate of a random mutation after only 100 generations. Over the course of human evolution—roughly 800,000 generations so far—a trait would vanish even if its fitness cost were as low as 0.001 percent. According to the best available estimates, however, 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. This web site shows the results of an opinion poll about the cause of sexual orientation. Poll results show that most people believe sexual orientation results from a person's environment or some aspect of his or her upbringing. The gay gene theory has been gaining ground, however, because of publicity given to papers that suggest the existence of a gay gene.
