It was arguably a poor choice of word. If a particular behaviour obviously has a significant selective advantage (at a cultural level) and becomes predominant i

It was arguably a poor choice of word. If a particular behaviour obviously has a significant selective advantage (at a cultural level) and becomes predominant it's done so on that basis. Whereas I'd think of a "default" as what would arise if you tried to start a new culture from scratch with a group of unconnected individuals with no exposure to other cultural ideas. The only defaults I'd expect to see are those driven by our biological makeup, e.g. we'd come up with a shared language that had certain basic properties, we'd adopt some sort of method of pair-bonding, we'd probably continue to have sex in private, and so forth, but to the level of specific taboos (whether it's discussion of sex, eating particular foods, wearing particular clothing etc.), I'm less convinced it makes sense to talk about defaults.