The following is an edited excerpt.
There’s been a lot of talk about nature in the gay-marriage debate. Opponents point to the “natural” link between heterosexual sex and procreation. Supporters note nature’s staggering diversity of sexual behavior and the ubiquity of homosexual sex in our close primate relatives. But, actually, gay marriage exemplifies a much more profound part of human nature: our capacity for cultural evolution.
Read the full article here: Culture Begets Marriage—Gay or Straight