1 Evolutionary Psychology

2 Asymmetrical Pressure “I have been noticing you around campus. I find you very attractive. Would you go out with me tonight?” –Women: 50% –Men:50%

3 Asymmetrical Pressure “I have been noticing you around campus. I find you very attractive. Would you come to my apartment tonight?” –Women: 6% –Men:69%

4 Asymmetrical Pressure “I have been noticing you around campus. I find you very attractive. Would you go to bed with me tonight?” –Women: 0% –Men:75%

5 Asymmetrical Pressure MenWomen Date50%50% Apartment69% 6% Bed75% 0% (Clarke & Hatfield, 1989)

6 Sexual Signaling Costly - require good health Honest - reflect good health

7 Sexual Signaling

8 Concealed ovulation: –competing pressures signaling fertility hiding lack of fertility

9 Attractiveness

10 Attractiveness

11 Attractiveness

12 Attractiveness

13 Attractiveness

14 Attractiveness

15 Attractiveness

16 Attractiveness Indicators of health/fertility: –HWR –symmetry & averageness of features both adults and infants demonstrate this preference Chinese and Japanese showed same preference (women show a preference for odor of symmetrical bodies only when they are ovulating) –youthful - baby face –fluctuating asymmetry (2D:4D) cultural differences

17 Paternal Uncertainty Gene shopping –Resemblance - does the baby resemble the mother or the father? mothers –rate infant as resembling the father mothers, if father present –rate infant as resembling the father mothers family –rate infant as resembling the father fathers –equally likely to rate infant as resembling father or mother (McLain et al., 2000; Knieps, 1997)

18 Paternal Uncertainty Response bias or greater paternal resemblance?

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22 Paternal Uncertainty Response bias or greater paternal resemblance? –impartial judges varies by study: –rate infant as resembling the mother –equally likely to rate infant as resembling father or mother (McLain et al., 2000; Knieps, 1997) “It’s a wise man who knows his own son.”

23 Paternal Uncertainty How common is gene shopping? Paternal testing laboratories –ranging from 1 in 7 to 1 in 10 children not sired by person identified as father Accurate?

24 Female Orgasm Sexual pleasure Domestic bliss Male ego Paternal confidence

25 A few Comments on Evolutionary Theory Adaptation vs. random genetic drift Punctuated equilibria vs. gradual evolution/adaptation –species do not evolve slowly –fossil record - leaps, not gradual change –fossil record - gradual changes suggests random genetic drift Evolution of new species vs... adaptation within species