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Understanding Male Sex Drive and Sperm Wars: An Evolutionary Perspective

Explore the evolutionary origins of male sexuality in preventing sperm warfare, maximizing fertilization chances, and avoiding cuckoldry. Delve into topics such as penis anatomy, thrusting dynamics, rapid orgasms, routine sex, masturbation, infidelity, and jealousy from the lens of male reproductive strategies. Discover insights into sperm types, insemination timing, the importance of routine sex, topping off sperm counts, and the impact of sexual starvation on male behavior. Gain a deeper understanding of male sex drive complexities and their evolutionary underpinnings.

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Understanding Male Sex Drive and Sperm Wars: An Evolutionary Perspective

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  1. Chapter 7 Male Sex Drive

  2. Sperm Wars (Baker, 1996) • Male sexuality evolved to prevent/fight sperm warfare • Maximize chance of fertilizing egg, passing genes on, & avoiding cuckoldry • Penis anatomy, thrusting & rapid orgasm • Routine sex & topping off • Masturbation • Infidelity & jealousy

  3. Penis Anatomy & Thrusting • Shape/thrusting cleans out other sperm • Suction • Larger the greater the suction • Rapid orgasm • Maximized insemination • Animals: Rapid insemination after infidelity • Why males find pornography so arousing

  4. Penis Anatomy & Thrusting • Reproductive disadvantage to male for female to have orgasm before sex • Increases strength of cervical filter • Males biologically destined to ‘rush’ w/o foreplay, climax rapidly

  5. Nature of Sperm • Average ejaculate contains 500 million sperm • 3 primary types: • Killers (fast, youngest, poison head) • Seek out and kill other men’s sperm • Blockers (slow, old) • Block other men’s sperm • Egg-getters • > 99% of sperm in ejaculate are killers or blockers • < 1% of sperm are egg-getters

  6. Nature of Sperm • Sperm live 5 days in female • 2 days to peak fertility • Egg dies w/in 1 day of release • Male must inseminate 3-4 days < ovulation • Best chance of conception if 2-3 days before • Sufficient killers & blockers to win sperm war

  7. Routine Sex & Topping Off • Hidden ovulation: Males consistently inseminate partner • Higher sex drive • Males adjust #, type sperm to keep healthy, fresh sperm in cervix (top off) • Delay since last sex (chance of foreign sperm?) • 5 days: 400 million • 3 days: 200 million • 3 hours: 30 million

  8. Routine Sex & Topping Off • Critical to winning sperm wars • Keep killer, blocker sperm population high • For 3 days post-intercourse • Aging of sperm in testes matches loss of blockers in cervix • Inject exactly the right amount of blockers to top off population

  9. Routine Sex & Topping Off • Columns of sperm in epitidymis • Closest to testicles youngest • Farthest away oldest (blockers, killers) • Adjust sperm via muscular contractions, number of spurts

  10. Masturbation • 98% males masturbate (3/wk, Class M = 4.89) • Many mammals also • Shedding sperm • Testes produce 300 million sperm/day • Shed 5 million/hour since last ejaculate • First to be ejaculated oldest

  11. Masturbation • Male body times urge to maximize chance of winning sperm wars • Purpose is to tailor ejaculate for next intercourse • Adjusting type, number of sperm • Shedding old, slower sperm • Best 2 days < insemination • Many young killers & blockers • Can be further adjusted depending on infidelity risk

  12. Infidelity & Jealousy • Sexually jealous/possessive of partners • Most jealous/in control less chance of cuckoldry • More HIS genes passed on • Male sexuality evolved w/ desire for numerous, fertile partners (even strangers)

  13. Item Long Shortp IQ 3.28 7.07 < .05 Emotional Stability 4.10 6.34 < .05 Honesty 3.17 6.07 < .05 Wealth 8.90 8.14 ns Health 6.48 4.10 < .05 Kind 3.93 6.10 < .05 Weight 5.52 2.69 < .05 Religion 7.48 4.19 < .05 Race 7.38 6.24 < .05 Attractive 3.00 1.24 < .05 Height 8.28 4.93 < .05 Family 9.83 10.17 ns

  14. Male Sex Drive • Men want lots of sex w/ lots of partners • Relationships are better but still... • Men want 50% more sex than they are having • Women sex desire = actual amount

  15. Sexual Starvation • Chronic sexual frustration inevitable for most men • High status males may be able to achieve satisfaction (Brad Pitt, Bill Gates) • Temporary

  16. Adaptation • Habituate to any S intensity • Taste, touch • Incrementally decrease R • Incrementally increase desired S • Money, Sports, Drugs • Lottery winners initial euphoria fades • Jordan & multiple championships • Pot gateway drug

  17. Adaptation

  18. Sexual Starvation • Sex • Virgins just want 1 • Then after 1 you just want 2-3 and so on • Made worse by social comparison (Festinger) • Compare w/ others to evaluate ourselves • Men may lie or be inaccurate • Volunteers different than non-volunteers • Media distorts sexual experiences of males

  19. Sexual Starvation • Males will never be sexually satisfied because no matter how much sex they have they will eventually adapt & want more • Doomed to be perpetually frustrated • Sexual boredom (males > females) • More masturbation & risky sex (prostitutes, unprotected sex, cheating) • Desire for big pay-off increases risk taking

  20. Reaction Paper III: Sexual Starvation • What is your reaction to the idea that men are fatally doomed to experience chronic sexual frustration, not getting enough sex even when married? • How do you think this will impact the way you deal w/ relationships in the future?

  21. Conclusion • Male sex drive complicated & may have evolved to prevent/fight sperm warfare • One consequence is high sex drive and perpetual sexual starvation via habituation

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