I believe that society is something that should focus foremost on sustained human happiness rather than striving for biological perfection. So, yeah, marriage > evolution.

Marriage is most definitely pro-evolution, in a very scientific way. For species like mammals who do not produce thousands of offspring, the survival rate for offspring increases dramatically when there are parents around dedicated to the survival of the offspring. Birds do this as well, though I don't know of any species who forms nuclear families in the same way as humans. "The strong spreading his seed" argument does not work because of both the dedicated parent issue, and because dedication to a single partner dramatically reduces the spread of sexually transmitted diseases and genetic defects. The benefits of the social structure of marriage far outweigh any "lack of reproduction" disadvantages since each woman can still produce multiple offspring with the same partner.

Ah. I suppose Vrael's right. Were we to assume that a woman could care for any amount of children by herself, then marriage would be anti-evolution, but the security provided by marriage leads to increased young survival rates.

Yeah, I really never thought of this... Although i would say it as that monogamy is pro-evolution, as marriage can technically, while not legally, happen between a man and any number of wives. Just look at ancient judeo-christian times, where a widow would marry her brother in law.

I meant marriage between a single man and a single woman for life.