New study answers "How could a 'gay gene' survive?"
Posted: Wed Jun 25, 2008 9:54 pm
I found an interesting genetics paper that puts a new light on the genetic basis for male homosexuality. The paper is here and it is also discussed in this blog. First of all, the problem:
Homosexuality is found at low frequency all human populations, which is one piece of evidence for a natural biological basis and probably a genetic cause in many homosexual/bisexual individuals. At first glance this creates a paradox: how could genes for homosexuality be maintained across all human populations if homosexuality is counterproductive to gene propagation? Shouldn't those genes die out? A number of LDS defenders have used something like this to argue against the proposal of gay genes. Two examples from prominent MADB posters who repeatedly make this argument:
The "natural-not-normal" equivocation has problems of it's own, but the interesting part of the quote is CI's recognition that homosexuality should be counterproductive to survival of the species, and this is somehow a problem.
Another example:
My reply to this type of assertion has always been to point out the social insects where a queen and a cohort of males do all the breeding, and most of the population seves other roles that do not involve breeding. And those sterile roles are vital for the survival of the whole colony. This shows that gene propagation and Darwinian mechanisms do not automatically preclude gay genes in humans.
This brings us to the paper "Sexually Antagonistic Selection in Human Male Homosexuality" and William Saletan's blog which gives a good summary of the initial observations:
Okay, so the women related to a gay man produce more children on average, and this is especially true for the women related to the gay man's mother. The authors of the study apply different genetic models to see if anything can account for these patterns. They conclude that the only model that accounts for the above pattern is one that posits a genetic factor for increased androphilia in both males and females that carry the factor. This "gay gene" would actually be an "androphilia gene" that causes men to be attracted to men, reducing their reproductive fitness -- but the upside is that female relatives who carry that same "androphilia gene" also find themselves increasingly attracted to men, resulting in more children. In balance, Darwinian mechanisms can select for the "androphilia gene" based on it's benefits in female reproductive behavior. This is a very interesting concept because it shifts the focus away from gay men, and includes the effects on all the women who also carry the "androphilia gene". (Note, this study says nothing for female homosexuality, but you can imagine a different gene influencing "gynophilia" in both males and females, resulting in lesbians but also male relatives who have more children on average.)
Considering this in the LDS context, maybe there could be a realization that gay men are the flip-side of the DNA coin that supports LDS women in having so many babies. Turning male homosexuals into second class members of the church doesn't seem like a charitable way to pay them back for "accepting" the same genes that make good "help meets" out of their sisters.
Homosexuality is found at low frequency all human populations, which is one piece of evidence for a natural biological basis and probably a genetic cause in many homosexual/bisexual individuals. At first glance this creates a paradox: how could genes for homosexuality be maintained across all human populations if homosexuality is counterproductive to gene propagation? Shouldn't those genes die out? A number of LDS defenders have used something like this to argue against the proposal of gay genes. Two examples from prominent MADB posters who repeatedly make this argument:
Confidential Informant wrote:When I say [homosexuality] is aberrant from a biological standpoint, I don't mean that it isn't "supported" by biology (whatever that means) What I am saying is this: It's pretty clear that as a biologicial imperative, procreation is the norm. How much of our evolution has come about because of the incessant push to promulgate the species? Homosexuality represents an aberration from that imperative. In other words, in may be "natural" but it is not "normal."
The "natural-not-normal" equivocation has problems of it's own, but the interesting part of the quote is CI's recognition that homosexuality should be counterproductive to survival of the species, and this is somehow a problem.
Another example:
Bill Hamblin wrote:The fittest are those who reproduce the most--or whose offspring survive in greatest numbers. Therefore, I submit, a purely Darwinian ethos requires all males to be as promiscuous as possible.
My reply to this type of assertion has always been to point out the social insects where a queen and a cohort of males do all the breeding, and most of the population seves other roles that do not involve breeding. And those sterile roles are vital for the survival of the whole colony. This shows that gene propagation and Darwinian mechanisms do not automatically preclude gay genes in humans.
This brings us to the paper "Sexually Antagonistic Selection in Human Male Homosexuality" and William Saletan's blog which gives a good summary of the initial observations:
Saletan wrote:First, male homosexuality occurs at a low but stable frequency in a wide range of societies. Second, the female relatives of gay men produce children at a higher rate than other women do. Third, among these female relatives, those related to the gay man's mother produce children at a higher rate than do those related to his father. Fourth, among the man's male relatives, homosexuality is more common in those related to his mother than in those related to his father.
Okay, so the women related to a gay man produce more children on average, and this is especially true for the women related to the gay man's mother. The authors of the study apply different genetic models to see if anything can account for these patterns. They conclude that the only model that accounts for the above pattern is one that posits a genetic factor for increased androphilia in both males and females that carry the factor. This "gay gene" would actually be an "androphilia gene" that causes men to be attracted to men, reducing their reproductive fitness -- but the upside is that female relatives who carry that same "androphilia gene" also find themselves increasingly attracted to men, resulting in more children. In balance, Darwinian mechanisms can select for the "androphilia gene" based on it's benefits in female reproductive behavior. This is a very interesting concept because it shifts the focus away from gay men, and includes the effects on all the women who also carry the "androphilia gene". (Note, this study says nothing for female homosexuality, but you can imagine a different gene influencing "gynophilia" in both males and females, resulting in lesbians but also male relatives who have more children on average.)
Considering this in the LDS context, maybe there could be a realization that gay men are the flip-side of the DNA coin that supports LDS women in having so many babies. Turning male homosexuals into second class members of the church doesn't seem like a charitable way to pay them back for "accepting" the same genes that make good "help meets" out of their sisters.