Statesboro, GA, USA
To believe that something suddenly becomes cold or something less than it is once the origin is understood doesn’t make any sense, I also can’t understand why you would prefer to believe that there is no love at all than a love created through evolutionary processes, could you explain?
If I take your view seriously, it really comes down to the disparity between what we understand love to be, and what love really is. We think of love, in terms that defy mere egoism, and pragmatism. The thoughts and feelings that love convey to us are sublime, and don't really fit with the discovery that it is just a chemical "tickle" in the brain to help an impersonal process of proliferating a certain kind of DNA.
If this were true, many of our assumptions about love would be undermined, because we would now know the "real" story. The feeling that personal devotion to someone else is based upon something virtuous or lofty, would become necessarily mythic. I can't help but think that a person who believes in the evolutionary origin of love, would begin at some point to doubt it altogether. (John seems to give us a good example of this, if I'm understanding him rightly, when he says that love is merely "a mask for lust")
If you deny that this is a valid concern, on my part, I would refer you to a host of existential philosophers, who took the materialist view of reality seriously, and ran into paramount problems in maintaining meaning, purpose, and hope. Many of their descriptions of modern "angst" are related to this tension between the "real story" of things, and the merely subjective definitions we attach to them.
In actual day-to-day experience I have seen it too. I am currently speaking to a young friend of mine, who is not a Christian, about some deep issues. He told me that it seems to him, if there were no personal God "behind" what's going on, he really sees no reason to feel optimistic about anything. Marriage was one of the things he felt would become a casualty, if blind materialism were accepted. In light of what you believe, do you never struggle with those kinds of thoughts? Maybe you've never followed the trail of your beliefs, in thought, to their full end, like the existentialist philosophers have. Or maybe you've chosen to remain optimistic about love, in a naturalistic scheme, in spite of where it might seem to lead.
Francis Schaeffer referred to this as the dichotomy between upstairs optimism, and downstairs rationality. If love is merely an evolutionary contruct, to believe that love is really love, there would have to be a Kirkegaardian "leap" into the upper story. Ibsen once said that "if you take away a man's lie, you take away his hope". To me, living as if the lie were true, but knowing otherwise, is unthinkable.
I would also like to mention that viewing "love" as more helpful to human reproduction and survival, than its alternatives, is mistaken. Lust does just as well as love, in making offspring. Has it been proven that love is superior in this regard? If love is only a chemical response in the brain to help survival, then "hate" is also just an alternate chemical response. You can survive by killing off competitors, and stealing their wives too. There's nothing in "nature", as such, to guarantee one more value than the other, in regards to producing offspring.
And if you reflect just a moment ... If you are genetically endowed with the "love method" of evolutionary success, then your preference for love is predetermined, and merely one of many impersonal and amoral tools. In which case, wouldn't your deep seated feelings about love being fundamentally "better" than hatred, be undermined? In fact such feelings themselves would seem to be part of the genetic predisposition.
So in summary: The materialistic evolutionary view of "love" is untenable for these reasons:
1) It isn't compatible with our human assumptions about what love really is.
2) Because of #1, it has lead to either despair, or a blind leap into optimism, for many brilliant thinkers in existential philosophy.
3) There is no proof that "love" is more fit than its alternatives, in the "survival of the fittest" scheme.