These countermeasures work in fair weather, when there's enough cohesion for them to go into effect. But in a vacuum
, there is no such context. In a vacuum, we only have individual behaviors. And the individual behaviors on aggregate for men
, in a vacuum, assuming no outside forces pressure them otherwise, is that they don't intrinsically care about the fate of children like mothers do, they just wanna nut, because they don't experience the radical psychological alterations upon pregnancy that make them bonded to the offspring they didn't just grow.
That's the point. The fact that there's a far greater tendency for the man to abandon the woman and child than there is for the mother to just dump the baby in a river shows that men aren't attached to children in the way women are.