>>724120087
Probably because it's an evolutionary benefit.
The younger the female, the lower the chance she's been run through by thirty(plus!) dudes, thus ruining the chance you might have of actually passing on your DNA, and also limits (if not outright eliminates) the chances of her having a disease.
Women are also far less likely to pair bond as they get older, thus becoming unreliable sluts which become a burden because they don't have a male mate to provide for them, and the offspring they have with non-involved sperm donors end up being defective retards that will harm the tribe (spiteful mutants).
It's almost as if for generations prior to the boomers, our parents and grandparents would work hard to get children and teenagers to engage in courtship to ensure they find life-long mates as easily as possible. It's almost as if all of that were destroyed and society is a mess because of it. Crazy huh?
