my theory-
since the cavemen- men LOVE to fuck- spread our seed- its an instinct- stronger in some. Not really about making babies on the surface- just need to have sex. When out cocks get hard- we can do really stupid , horrible, things- rape, murder assault. How many men are in jail, either directly or indirectly, because they are serving these primitive impulses
?? Nature gave men a strong sex drive. Woman take advantage of it endlessly as well..
Woman- have a safe nest instinct- works much better if one loyal man protects, provides, than if he has divided interest.