Chapter 7
Male Sex Drive
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
Penis Anatomy & Thrusting
 Shape/thrusting
cleans out other sperm
 Suction
 Larger
 Rapid
the greater the suction
orgasm
 Maximized
insemination
 Animals: Rapid insemination after infidelity
 Why
males find pornography so arousing
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
Nature of Sperm
 Average
ejaculate contains 500 million sperm
 3 primary types:
 Killers
 Seek
(fast, youngest, poison head)
out and kill other men’s sperm
 Blockers
 Block
(slow, old)
other men’s sperm
 Egg-getters
>
99% of sperm in ejaculate are killers or blockers
 < 1% of sperm are egg-getters
Nature of Sperm
 Sperm
2
live 5 days in female
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
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
5
since last sex (chance of foreign sperm?)
days: 400 million
 3 days: 200 million
 3 hours: 30 million
Routine Sex & Topping Off
 Critical
 Keep
 For
to winning sperm wars
killer, blocker sperm population high
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
Routine Sex & Topping Off
 Columns
 Closest
of sperm in epitidymis
to testicles youngest
 Farthest away oldest (blockers, killers)
 Adjust sperm via muscular contractions,
number of spurts
Masturbation
 98%
males masturbate (3/wk, Class M = 4.89)
 Many
mammals also
 Shedding
 Testes
sperm
produce 300 million sperm/day
 Shed 5 million/hour since last ejaculate
 First to be ejaculated oldest
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
 Best
old, slower sperm
2 days < insemination
 Many
young killers & blockers
 Can be further adjusted depending on infidelity risk
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)
Item
IQ
Emotional Stability
Honesty
Wealth
Health
Kind
Weight
Religion
Race
Attractive
Height
Family
Long
3.28
4.10
3.17
8.90
6.48
3.93
5.52
7.48
7.38
3.00
8.28
9.83
Short
7.07
6.34
6.07
8.14
4.10
6.10
2.69
4.19
6.24
1.24
4.93
10.17
p
< .05
< .05
< .05
ns
< .05
< .05
< .05
< .05
< .05
< .05
< .05
ns
Male Sex Drive
 Men
want lots of sex w/ lots of partners
 Relationships
 Men
are better but still...
want 50% more sex than they are having
 Women sex desire = actual amount
Sexual Starvation
 Chronic
sexual frustration inevitable for
most men
 High status males may be able to
achieve satisfaction (Brad Pitt, Bill Gates)
 Temporary
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
Adaptation
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
 Men
w/ others to evaluate ourselves
may lie or be inaccurate
 Volunteers different than non-volunteers
 Media distorts sexual experiences of males
Sexual Starvation
 Males
will never be sexually satisfied
because no matter how much sex they have
they will eventually adapt & want more
 Doomed
 Sexual
 More
to be perpetually frustrated
boredom (males > females)
masturbation & risky sex (prostitutes,
unprotected sex, cheating)
 Desire for big pay-off increases risk taking
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?
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