Apparently, if you're a guy who wants his chances of evolutionary survival to go up, you should be going down.

According to a new study published late last month in the Journal of Evolutionary Psychology, heterosexual men perform oral sex on their partners as a "mate retention" strategy — in laymen's terms, to keep the ladies coming back for more.

This, in turn, reduces the likelihood of infidelity and increases the chances that your female partner will stick around long enough to carry your baby and advance your genes into the next generation.

Oakland University in Rochester, Mich., surveyed 243 adult men in committed, heterosexual relationships regarding their sexual behaviors. Researchers sought to test the hypotheses that men perform cunnilingus to: 1) promote sperm retention, since uterine contractions during female orgasm pull sperm further into the reproductive tract and, therefore, make it more likely for a pregnancy to occur 2) promote mate retention by deterring competition from other sperm sources, since men who bring their female partners to orgasm are presumably more sexually satisfied and, thus, less likely to turn to other men for sex.

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According to the research, the sperm retention theory did not hold, but mate retention appears to be a driving, evolutionary reason behind men's performance of oral sex on women. Making a woman happy through oral sex reduces the likelihood of "cuckoldry," defined here as a man's "unwitting investment of resources into offspring to whom he is genetically unrelated."