That's the wrong way to think of it. Rather, it must not be a crippling survival disadvantage or we would have stopped doing it. And happiness doesn't necessari

That's the wrong way to think of it. Rather, it must not be a crippling survival disadvantage or we would have stopped doing it. And happiness doesn't necessarily correlate with survival either. I don't remember the name, but in an anthro class we discussed a culture where children were married as infants and raised together. This ends up being suboptimal because the kids identify each other as siblings and biology basically interferes with them developing a romantic relationship. As a result they end up taking romantic partners outside the arranged marriage. But hey, it still produces kids so the culture continued on, even with this suboptimal practice. Likewise for tribes who practiced eating the brains of the deceased. It gives you a neurodegenerative disease, but the incubation period is sufficiently long so that you can still keep your population up.