Quote from the article:
What Cochran suspected about homosexuality, he and his colleague
now believe to be true for a large number of conditions¡ªnamely,
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¡±¡ªthat 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¡ªa mistake known as a random
mutation¡ªand 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¡ªsuch as the gene for sickle-cell anemia, which also
happens to ward off malaria.) The higher its fitness cost, the
faster a gene disappears. Like the basis of most scientific
paradigm shifts, Cochran and Ewald¡¯s idea sounds obvious once
they¡¯ve pointed it out: It is almost never in our evolutionary
interest to develop genes for diseases. But what does this have to
do with homosexuality? Remember your mother¡¯s idðfixe. She
doesn¡¯t care about your hobbies; she wants to see infants.
Unhappily for her, modern homosexuals have only one fifth
as many children as heterosexuals do, according to a San Francisco
study published in 1981. That puts the fitness cost of
homosexuality at 80 percent¡ªstaggeringly high from the perspective
of human evolution. If there is a
gene for homosexuality, nobody has figured out why it
survives. As lesbians and gay men have won
liberation and come out of the closet, they have probably become
less likely to marry and produce children; some researchers have
suggested, therefore, that in the past, when homosexuals lived more
closeted lives, they reproduced at a rate closer to that of
heterosexuals. But even under a regime of compulsory
heterosexuality, disinterest in the opposite sex would still have
lowered the rate of reproduction. Nor will the current ¡°gayby
boom¡± turn the tide. Gay parents are still very far from
matching the fertility rate of straight parents. 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¡ªroughly 800,000 generations so far¡ªa 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.
As above, in the bold & other sentences, it's just
impossible that the gay gene hasnt died out after so many yrs of
evolution bcos it's a disease genetic mutation & homos dont
reproduce as well as non homos. The last sentence says it all.
There's too many homos for the condition to be genetic. The maths
just doesnt add up!
