I’ve barely scratched the surface of the evolved semen literature. Here’s a snapshot of other recent findings from Gallup’s lab: semen-exposed women perform better on concentration and cognitive tasks; women’s bodies can detect “foreign” semen that differs from their recurrent sexual partner’s signature semen, an evolved system that, Gallup believes, often leads to unsuccessful pregnancies because it signals a disinvested male partner who is not as likely to provide for the offspring; women who had unprotected sex with their ex-partners—and therefore were getting regularly inseminated—experience more significant depression on breaking up than those who were not as regularly exposed to their ex’s semen (and they also go on the “rebound” faster in seeking new sexual partners, which presumably would help fix their semen-deprived depression). And the list goes on.