Except that this isn't nature, it's patriarchy. When women were stripped of their co-equal roles as food producers for the tribe a mere 6-9 k years ago and forced to rely on one man for support in a dominance based society, there was incentive to pick one as high up the pyramic as you can acquire. But even today, Pew research indicates that both men and women consider being a kind and caring partner more important than being a "provider" - something that men believe is important for them to do as well.