One can, in effect, treat the sexes as if they were different species, the opposite sex being a resource relevant to producing maximum surviving offspring. - Robert Trivers (1972)

 Men and women designed for lifetime deep, monogamous love  Female fidelity is good for males, so females developed fidelity

 all known human cultures have marriage (though varying types of marriage) › having a family is the norm › but 980 of 1154 human societies allow men to have more than one wife  though polygynous marriage is not the norm

 amount of resources, time, energy, etc, male parents spend on raising their children  humans exhibit high MPI relative to other species

 Moved from forests into savanna  Became smarter and more upright › Narrow pelvis  Clinging baby + mother gathering food › helpless tiger bait

 Females reproduce once in a long time  Females should be more selective about who they mate  Want high ongoing investment

› Women: average intellect › Men: average intellect  Intelligence of someone you’d have sex with? › Women: Oh, in that case, above average intellect › Men: Oh, in that case, below average intellect

 As much sex as they can get away with  Attracted to fertile-looking females  High MPI species, so s omewhat selective

 measured with electrodes on skin › Sexual infidelity – Men more upset › Emotional infidelity – women more upset

 two kinds of women: the kind you respect and the kind you just sleep with  “the male may actually encourage the early sex for which he will ultimately punish the woman.”

 Men and women tend to be, respectively, exploiter and exploitee  Men have more to gain from deserting family

 Selection favors males who can deceive about future devotion › Self-deception effective too  Selection favors females who can spot deception

 “resource extraction” hypothesis  “seeds of confusion” hypothesis  “best of both worlds” hypothesis  Women are more sexually active around ovulation.

 Successful male infidelity is advantageous for males  And if female infidelity was not long- standing…  Average testes weight to average male body weight

 Margaret Mead › No needless anxieties about sex › Casual lovemaking › No ideas of exclusiveness, jealousy, or undeviating fidelity › If husband caught wife in adultery, appeased by harmless ritual

 Derek Freeman  Upon marriage, good girls manually deflowered  If girl found with a boy and suspected to have lost her virginity, her brothers would “upbraid and sometimes beat” her  Young men who failed at the mating game sometimes “forcibly deflower” a woman and threaten to tell others unless she married him  If woman found to be non-virgin on wedding day, publically denounced “whore”

 Madonna or whore, cad or dad?  During childhood, assess local social environment  More attractive adolescent girl, more likely to “marry up”  Evolutionarily advantageous to be flexible

 Could think of many different hypotheses for why these sexual strategies were shaped  But cannot argue that evolutionary psychology is irrelevant to the whole discussion

 monogamy is not our nature  Might be better off without this strict monogamy