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Sexual selection
- 1.
- 2. Sexual Selection ◦The processthrough which males and females attempt to maximise their chances of reproductive success
- 3. Sexual Selection ◦There are2 different types of Sexual Selection ◦1. Intrasexual Selection ◦2. Intersexual Selection
- 4. Intrasexual Selection ◦ MateCompetition ◦ Members of one sex compete against each other to attract members of the opposite sex ◦ Usually this is between 2 or more males
- 5. Intersexual Selection ◦Mate Choice ◦Femaleschoose between male mates. ◦‘Between sexes’
- 6. Gender differences inReproductive Behaviour in humans ◦Differences in Quantity of mates ◦Differences in Longevity of mates ◦Differences in Sexual Jealousy ◦Differences in Sexual Fantasies
- 7. Intersexual Selection ◦ Inmost Mammal species, the female invests heavily in the offspring ◦ Especially in species where females have limited reproductive opportunities ◦ Thus females need to be picky and make the right selection of male ◦ A wrong choice for a female is much more serious than for a male – this leads to intersexual selection
- 8. Females Choosiness For afemale it pays to be choosey due to investment ◦The genetic quality of your mate will determine half the genetic quality of your offspring ◦Selection for ‘Good Genes’ and ‘Good Parents’ ◦Will the mate survive and be able to provide for, protect and support their offspring?
- 9. TASK: Intersexual selection Whatcharacteristics would indicate good resources? What characteristics would indicate good genes? What characteristics would indicate good parents? Economic & financial security, good job, well educated, interpersonal skills, status, etc Good health i.e. skin, hair, weight, facial symmetry, BUT also traits that are disadvantaged (peacock’s tail) Good skills, caring, affectionate, strong, protective, ability to provide, nurture, etc
- 10. Short & Longterm mating strategies ◦ Males: ◦ Short term strategy = casual sex sought as early as possible in the relationship ◦ Explains why males may lower their standards prior to sex then lose interest quickly after sex ◦ Females: ◦ Long term strategy = men who are resourceful and protective are preferred. ◦ Males who show potential to be a good parent (caring, affectionate)
- 11. Short Term vs.Long Term strategies ◦ Clear differences have been found in the behaviour of men and women in terms of short term strategies. ◦ Clark and Hatfield (1990) conducted a study where male and female experimenters approached members of the opposite sex with the following statement: ◦ ‘Hi, I’ve noticed you around campus and I find you very attractive’. They then asked them either: ◦ (1) ‘Would you go on a date with me?’ ◦ (2) ‘Would you go back to my apartment with me?’ ◦ (3) ‘Would you have sex with me’.
- 12. Clark & Hatfield(1990) ◦ 50% of both men and women agreed to go on a date ◦ Of the females asked, 0% agreed to have sex, compared to… ◦ 75% of males approached! ◦ Demonstrates intersexual sexual selection differences in males and females
- 13. Mate Preference ◦ Malesare also picky as they will ultimately have to provide many resources to the female and offspring ◦ Men have evolved to prefer females who display fertility ◦ Optimum waist-hip ratio ◦ Large breasts ◦ Youthfulness ◦ Baby-faced features (large eyes/small nose)
- 14. Buss (1989) ◦Demonstrated genderdifferences in modern relationships ◦37 cultures in 6 continents ◦10,000+ participants ◦Questionnaire on mate preferences
- 15. Buss (1989) ◦ Acrossall cultures… ◦ Women showed a preference for males with resources or possessing characteristics that would translate to resources (intelligence/ambition) ◦ Women preferred a high-status male on average 5 years older than themselves
- 16. Buss (1989) ◦ Acrossall cultures… ◦ Men placed more emphasis on physical attractiveness (indication of woman’s health/fertility) ◦ Men desired a partner who was younger than themselves ◦ Both sexes wanted kind, dependable partners
- 17. Buss (1989) ◦Findings representa clear illustration of evolved sex differences based on sexual selection ◦Show cultural universals = likely to have evolved across the human species as a whole
- 18. Buss (1989) –Criticisms… ◦ Self – report data ◦ Lacks Validity… ◦ Buss conducted a study on marriages in 29 cultures and found men do marry younger women… and remarry even younger ones!
- 19. AO2 – Matepreferences ◦Waynforth and Dunbar (1995) ◦Analysed Lonely Heart adverts ◦Found that adverts reflected evolutionary pressure to promote reproductive success
- 20. Waynforth and Dunbar(1995) ◦ Found that men indicated material wealth in their descriptions of themselves twice as often as women ◦ Women demanded wealth in a potential parter 4.5 times more often than men ◦ Females twice as likely to provide information about their physical appearance
- 21. Female Fertility ◦Many animalshave ways of demonstrating fertility to males ◦Women have also evolved this, but it is mostly subconscious
- 22. ◦ Women areat their most fertile in the 2nd week of their cycle ◦ Research has shown that women’s faces and scent becomes more attractive during this time ◦ Women also become more confident
- 23. Miller et al(2007) ◦Measured lap dancer’s tips of dancers on and off the pill (fertile/infertile) ◦During non-fertile stages, both sets earned similar tips ◦During ‘fertile’ stages, the non-pill dancers received significantly more in tips
- 24. Female Fertility ◦Women’s choicein men also changes throughout the menstrual cycle…
- 26. Penton et al(1999) ◦Women attracted to more masculine looking men during their most fertile time ◦Preference for more feminine looking men during less fertile times
- 27. Penton et al(1999) ◦Less-masculine men = better long term partner (kinder/cooperative) ◦But women may benefit from being unfaithful during the fertile phase with a strong/healthy child with a more masculine looking man
- 28. AO3 Gender Reductionist Ethical Guidelines? Nature vs.Nurture Animal Studies Determinsm vs. Free Will Ethnocentricism
- 29. Gender Bias ◦ Shortterm mating should not occur amongst females as it is not evolutionary beneficial to us ◦ Females do still engage in casual, short term relationships. ◦ The theory doesn’t account for wide use of contraceptives which reduce female risk yet go against the key principle of evolution ◦ It can therefore be seen as a reductionist theory, limiting human relationship behaviour to merely procreating
- 30. AO3 Gender Reductionist Ethical Guidelines? Nature vs.Nurture Animal Studies Determinsm vs. Free Will Ethnocentricism
- 31. Deterministic ◦ All evolutionarytheories assume that human behaviour is driven by primitive forces that we have no free will to change ◦ The theory doesn’t account for individuals who do not want to procreate ◦ It also does not account for homosexuality
- 32. AO3 Gender Reductionist Ethical Guidelines? Nature vs.Nurture Animal Studies Determinsm vs. Free Will Ethnocentricism
- 33. Nature/Reductionist ◦Only considers the‘nature’ side of the argument ◦Doesn’t take into account environmental factors which may influence mate preferences ◦Methods used to collect data (i.e. self-report) may not reflect actual mate choices
- 34. AO1 ◦ Sexual Selection ◦Intrasexual selection – Mate Competition ◦ Intersexual selection – Female Choice ◦ Reproductive Behaviour ◦ Short/Long term mating strategies
- 35. AO2 ◦Buss (1989) ◦Clark &Hatfield ◦Waynforth & Dunbar ◦Miller ◦Penton
- 36. AO3 Gender Reductionist Ethical Guidelines? Nature vs.Nurture Animal Studies Determinsm vs. Free Will Ethnocentricism
Editor's Notes
- #19 Validity – ideal vs realistic choice