a tremendous challenge to Darwinism. Many animals,
including humans, exhibit clear homosexual mating behaviors and associated
traits. In some species, up to a few percent of the population is homosexual.
While scientific data is weak compared to other studied behaviors, homosexuality
is known to be widespread, persistent across species, and is not a cultural
artifact. Therefore, homosexuality is most likely a genetically determined
According to Darwin,
genetically-linked behaviors die out if they do not confer a survival
benefit. Which raises the question, how can homosexuality confers survival
advantages on the individual, if it has no way to propagate without a
way to procreate?
On possibility is
that homosexuality might confer a mild genetic advantage if related group
members are more likely to survive due to the assistance of a helpful
"uncle". In this manner, part of the uncle's genetic code is
indirectly preserved across generations. Another possibility is that homosexuality
may arise as the unintended consequence of a common mutation. Or, it may
emerge as side-effect from a different, environmentally fit characteristic
which persists by conventional evolution between generations..
A mystery, indeed.
But what if homosexuality
were a result of sperm competition?
Sperm, of course, benefit most greatly if they can actually fertilize
an egg, and pass their genetic code onto another generation. In many animals,
the male (and very frequently, the female) are promiscuous- so sperm from
more than one suitor vie simultaneously to fertilize an egg. But, if one
sperm loses the battle of procreation, the next best strategy might be
for the losing suitor's sperm to kill off the winner's zygote.
Now, sperm could try
to directly kill the zygote, but natural selection would just as rapidly
evolve a countermeasure for so profound a loss. On the other hand, if
the competing sperm simply changed the egg's biochemistry, so the animal
became a homosexual, then the gene would be deleted from the pool, but
at a much later date. A gay time bomb, so to speak.
investigations show sperm carry and deliver a number of active
molecules beyond DNA. And, other investigators believe even small
amounts of hormones in the environment can strongly affect embryonic development
and sexual maturation. So this hypothesis- that the "losing"
sperm retaliate by chemically modifying the development of the winning
zygote- is plausible. One place to look for evidence is the rate of homosexuality
in babies conceived by in-vitro fertilization- where sperm competition
is absent. If the rate were different than expressed in the general public,
further studies are warranted.
Over time, we are
likely to discover the egg's development is crtically influenced by the
local chemical environment, and the local chemical environment may be
radically shaped by the actions of millions of second-place sperm.