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Sexual Selection

Sexual Selection. Psychology 3107. Introduction. A species’ ecology should dictate what traits are optimal Natural selection Explain this then. What is Sexual Selection?.

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Sexual Selection

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  1. Sexual Selection Psychology 3107

  2. Introduction • A species’ ecology should dictate what traits are optimal • Natural selection • Explain this then

  3. What is Sexual Selection? • Sexual selection is ‘the advantage which certain individuals have over others of the same sex… in exlcusive relation to reproduction’ Charles Darwin • So, it is NOT about the environment, but about mate choice really

  4. Intra Sexual Selection • Usually Male – Male • Leks • Body Size • Weapons • Could be all of the above, some of the above, or, of course, others • Ornamentational

  5. Inter Sexual Selection • Once you ‘win’ (you being a male) then inter sexual selection starts • Females choosing males (usually) • This can lead to strange things like peacock feathers, combs, antlers or stupidly long tails!

  6. Inter sexual selection • Why would a female choose something so ridiculous? • Could indicate good genes • Could indicate strength • Could indicate parasite resistance • Could just be nuts • Runaway selection

  7. Questions • Can I buy you a drink? • Would you like to go out with me? • Wanna have sex? • (Clark and Hatfield, 1989) • 73 percent of men • NO women • There is a difference here, why deny it?

  8. Sexual selection in humans • Intra sexual and intersexual selection • A woman can produce one child a year • A guy can produce as many as he can… • Paternal investment slows reproductive rates of men • So what are the humans like, are we like deer or like well the Vulcans…

  9. Then again • We are both, men and women, still choosy • 27 percent of men did say no to the offer of sex • This would not happen in other mammals usually • So both sexes are choosy, it just depends on what for

  10. Beauty is in the adaptations of the beholder… • Well maybe we are after good genes (seems reasonable…) • Maybe attractiveness is related to parasite load • We have to choose a mate that is most likely to produce pathogen resistant offspring

  11. MHC • MHC genes build our immune system • We should prefer mates that are similar in most characteristics but different in MHC genes • Boy how could we test that? • Umm, well go for a run and let me sniff your armpits…

  12. Parental investment • Men’s is economic • Women’s is physiological • So what should we prefer then? • Women should rate economic stuff (oh say salary) as more important than men do • But I thought women were in the work force and all that, and all the socialization • Yes of course

  13. Is that your wallet in your pocket or are you just glad to see me? • Personal ads • 11 to 1 ratio! • Ask single women, they rate it more important, much more important, than men do • Put downs of others’ resource acquiring ability • THIS IS CROSS CULTURAL

  14. Structured powerlessness • So, maybe women prefer this because, well that is how stuff works, I mean guys just have more access, so it makes sense to prefer guys with bigger wallets • So then it would follow that women with much access to power would not care about a man’s earning power

  15. Ummm no… • Newlyweds studied by David Buss • No relationship between income and importance in men, a nice positive one in women • It turns out, in fact, that women that will probably make more, or do make more actually care MORE about the earning power of their potential mate!

  16. Ok, what do men want? • Women, lots and lots of fertile women…. • Men like youth • Men like clear skin • Men like symmetry • The waist to hip ratio is a good indicator of fertility • .7 or so

  17. Strategies mixed and pure • People are unfaithful • Hard to get rates, though the study at the beginning gives us an idea • When messing around, what do we prefer? • Men’s standards are lower…. • jealousy

  18. Remember • Do NOT fall for the naturalistic fallacy • Nobody is saying we do this consciously • Interesting though that now with women increasingly in the workforce and with men doing more childcare these differences seem to be steady

  19. Conclusions • Traits may co evolve with preferences • The hypotheses ARE NOT mutually exclusive • Perceptual mechanisms and their constraints play a big role (Shettleworth, 1998)

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