I've come to the sad conclusion that it is impossible to impart what
most of us see as common sense into people who claim to understand the
logic behind the theory of evolution, yet profess to seeing nothing
wrong -- or even unusual -- about sexual practices that by themselves
would guarantee the end of the human race.

That sentence makes no sense. By "by themselves" do you mean "if the
only kind of sex were gay sex, there's be no reproduction"?, or do you
mean "in and of themselves", as in the simple act of engaging in gay sex
will guarantee the end of the human race? If the latter, there is much
evidence to the contrary (gay sex has been around since the beginning of
history, and probably since the beginning of evolution). If the
former, then the same could be said for eating chocolate. (If the only
thing people ate was chocolate, the human race wouldn't last long
either). And eating is just as important as sex.

Therefore, I don't find your statement above to be convincing. It has a
serious error in logic. And to argue that "there's no comparison
between gay sex and eating chocolate" is to say that you really are
reaching your conclusion through reasoning other than what you just
presented.

If they had any sense at all,
they would spend their political capital on
obtaining equal rights for same-sex unions
-- call them whatever youwant, except "marriage"

You seem to be trying to give the impression that you are ok with same
sex unions (let's call them "ssunions") having the same rights as
married heterosexual couples. However, this is an illusion. So long as
private contracts (of which there are millions) have the opportunity to
use the word "marriage" to mean one thing, and ssunion to mean the other
thing (which is the whole point), then those private contracts can
easily deny benefits to ssunions that they grant to marriages, thus
defeating the impression you seem to want to give. Further, the
millions of contracts already written (such as health care contracts and
hospital visitation rights) will retain all the discrimination that
"equal ssunions" is designed to make us believe it eliminates.

Therefore, I believe you are giving lip service to one idea while
actually supporting another. Whether deliberate or not I cannot say.
But this is the reason why "Separate but equal" flies as well with gay
couples as it does for blacks.

No mainstream national politician
can support such a stance...

Perhaps not in the present atmosphere. In that case, just like in the
sixties, the aim is to change the atmosphere.

... the specious claims that these couples
are somehow "married" or "normal".

Whether they are "married" or not is a simple matter of definition.
That can be changed at the stroke of a pen.

Whether or not it is "normal" begs the question of what "normal" means.
If two percent of the population has green toes, is it normal to have
green toes? No. However, it =is= normal for two percent of the
population to have green toes.

It is also quite possible that, while green toes puts an individual at
an evolutionary disadvantage (easier to be seen by predators), having a
population where some people have green toes is an advantage to the
population (by attracting predators they also attract food), and having
a strong population is itself an advantage to all individuals
(protection from predators).

So, your reasoning above is flawed, making use of the emotional baggage
carried by the word "normal" while being very loose in its actual meaning.

Jose
--
"Never trust anything that can think for itself, if you can't see where
it keeps its brain." (chapter 10 of book 3 - Harry Potter).
for Email, make the obvious change in the address.