"The 'fight or flight' model is based on the very simple assumption that our bodies prepare us for action to either fight with a foe or to run away from it. However, from an evolutionary standpoint, women evolved as caregivers; applying the same 'fight or flight' model, if women fight and lose, then they are leaving an infant behind. By the same token, if they flee, it's a lot harder to flee if you are carrying an infant and you're not going to leave the infant behind."