A female human being does not have to share her sexual favors with many males to prevent infanticide, but she may have a good reason to share them with one well-chosen male apart from her husband. This is because her husband is, almost by definition, usually not the best male there is—else how would he have ended up married to her? His value is that he is monogamous and will therefore not divide his child-rearing effort among several families. But why accept his genes? Why not have his parental care and some other male’s genes?
