We know that biologically, human males have a strong, measurable sperm-competition cue response.

I’ve mentioned this before, but sexuality experts speculate that’s why most men prefer mixed-sex porn and not porn featuring only women.

The sight of another erect penis will typically cause a man to become more erect and ejaculate more powerfully, even though he would not typically report finding the sight of that erect penis sexually stimulating.

Evidence of sperm competition cues among human males is powerful evidence that we are not wired for sexual monogamy.

Sexual monogamy is actually something many of us agonize over. We struggle to live up to an ideal that is very unnatural for us. So many of the tears and drama we put ourselves through could be reduced if we could just alter our expectations a little bit while being kind and loving to one another.