Are we born to an evolutionary purpose?

Well, sure, a sufficiently creative person can come up with a scenario where almost any behavior can produce a reproductive advantage. One of my favorites was from an article in Newsweek where the science reporter was talking about where she and her college buddies came up with the reason men prefer women in short skirts: women wearing long dresses were more likely to trip on the hem and squash the babies.On the other hand, this was a major criticism leveled against Darwinism for a long time after publication of Origin of Species. Darwin's theory of common descent was widely accepted almost immediately; however, natural selection was quite controversial until the Modern Synthesis was developed. Criticisms against natural selection in general complained that Darwinists simply made up "just so" stories to explain why certain features were adaptive; however, a sufficiently creative person could come up with a scenario explaining why almost any trait might be adaptive.

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Actually, if their god makes better pancakes, I'm totally switching sides. -- Charley the Australopithecine

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Why would gay guys even be born if there is so much less chance that they're genes will get passed on? What evolutionary advantage (considering passing on genes) do gay men have over straight? Why would natural selection even come/end up with that?

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Well, assuming that there is such a thing as a genetic component to homosexuality, there are several possibilities.It could be something like sickel cell -- a person who is heterozygous for this set of alleles might be "more fit" in other areas, allowing them to outcompete homozygous heterosexuals.Or, like genetic altruism, it might not be so much the homosexual person who is passing on his or her genes, but by having more resources to contribute to the tribe or band might enable those who are heterozygous carriers of the homosexual alleles to survive and reproduce (and therefore produce more offspring with these alleles).

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Actually, if their god makes better pancakes, I'm totally switching sides. -- Charley the Australopithecine

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But we could come up with the same sort of reasoning for almost any kind of human.

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Exactly, which is why simply coming up with some way that a given trait might be adaptive is not evidence that the trait is adaptive -- merely an assertian that such a trait is not necessarily counter to natural selection. But as anastasia is pointing out, good reasons can also be given for any given trait to be maladaptive. For instance, homosexuality may be adaptive for the reasons I just gave; an innate tendency to rape may be adaptive as it will impel the individual to engage in behavior that will lead to reproduction. On the other hand, homosexuality may be maladaptive as an act of nonreproductive homosexual sex is time an effort not spent in reproductive heterosexual sex; rape may be maladaptive as the social unit upon which the rapist, the parent of the child, and the child depend unravels and also as the stigmatized offspring suffers a greater chance of neglect and death.So which wins out? Who knows? As was pointed out in the recent Eocene mammal thread, to know exactly what traits will be adaptive would require almost infinite knowledge of all the parameters of the environment in which the individual and the tribe lives.

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Actually, if their god makes better pancakes, I'm totally switching sides. -- Charley the Australopithecine

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To speculate that evolution has opted for every trait known to man, and to assume that we have been given that trait to fulfill a distinct niche automatically according to need, is comparable to making evolution 'intelligently' able to predict need and to measure population, etc.

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Well, I don't agree that these speculations are comparable to making evolution "intelligent". I do agree, though, that a lot of the speculation about the biological basis for human behavior is silly and nonproductive.It is a fair question to ask how much, if any, human behavior is due to biology, and how much of this biological nature is due to genetics.Before we can even intelligently ask what, if any, evolutionary advantage this or that behavior provides, one must first demonstrate that the particular behavior is, in fact, due to biology and not simply learned cultural behavior. When it is determined that the behavior is biological, then one must determine whether it is actually genetic in origin.Then one can wonder whether the behavior was actual adaptive during the evolutionary history of our species, or whether it is merely an "inadvertent" side effect (a "spandrel") of other traits that were adaptive. One can also ask that if it were adaptive, was it adaptive during the recent history of our species? Or was it adaptive long, long ago in the evolutionary history of our species, a left over "vestigial behavior", like the appendix, which hasn't yet been completely eliminated?

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Actually, if their god makes better pancakes, I'm totally switching sides. -- Charley the Australopithecine