1. Human Mating Strategies

2. Central Question
Can humans be shown to mate in a manner consistent with the hypotheses surrounding mate choice by either perception of genetic quality or of ability to provide resources?

3. Human Reproductive Investment
1. Female investment in offspring – very high
Male investment in offspring – variable
2. Reproductive life
Female
Male

4. Human Reproductive Investment
3. Reproductive “down time”
pregnant
reproductively ‘available’
Female
Female
Male

5. Three components to consider
1) Human mating is strategic
2) Mating strategy is context dependent
3) Men and women have faced different problems and will have different strategies

6. Look at sexual strategies that males and females might pursue
Look in the context of
a) short term mating
b) long term mating

7. Elements of female strategy
Type of mating
Elements of male strategy
-number of partners
-immediate resource extraction
-identifying sexually accessible women
-evaluating short-term mates as potential long term maes
Short-term
-minimize cost, risk, commitment
-attain men with high quality genes
-cultivate potential back-up mates
-identify women who are fertile
-paternity confidence
-identify men willing & able to invest
Long-term
-assessing a woman’s reproductive value
-physical protection from aggression
-identify men who will commit
-identify women with parenting skills
-identify men with good parenting skills
-attaining women with high quality genes
-attaining men with high quality genes

8. Hypotheses arising from previous slide
1) Short term mating is more important for men than women
Very likely
Very unlikely

9. Question: If you could mate with a member of the opposite sex who was no more or less attractive than your permanent mate and there was no risk of disease, discovery or forming a permanent liaison, would you do it?
100 80 60 40 20
Probably/certainly not
- Females - 91%
- Males - 50%
- Males
- Females
Certainly would
Probably would
Probably not
Certainly not

10. Hypotheses arising from previous slide
2) Men seeking a short term mate will solve the problem of identifying women who are sexually accessible
-survey of 44 men and 42 women
-survey of 44 men and 42 women
Men – value experience and promiscuity in short term but not long term mate
Women–experience and promiscuity not desirable in either mate

11. Hypotheses arising from previous slide
3) Men seeking a short term mate will minimize commitment and investment
-survey of 44 men and 42 women
Men – value commitment and investment in long term but not short term mate
Women–commitment and investment desirable in either mate

12. Hypotheses arising from previous slide
4/5) Men seeking a short term mate will solve the problem of identifying fertile women while men seeking a long term mate will solve the problem of identifying reproductively valuable women
Fertile – refers to the probability that a woman can conceive a child
Reproductive value – expected future reproduction
Generally, men should prefer mates who are younger than themselves

13. Age preference in mates in males and females

14. Hypotheses arising from previous slide
6) Men seeking a long term mate will solve the problem of paternity confidence
Value placed on chastity

15. Hypotheses arising from previous slide
7) Women seeking a short term mate will prefer men willing to impart immediate resources
-survey of 44 men and 42 women
Women – place greater importance on gift giving in a short term mate
- especially negative to ‘stingy’ men

16. Hypotheses arising from previous slide
8) Women will be more selective than men in choosing a short term mate
-survey of 44 men and 42 women
-women are seen as engaging in more prospective long term mate assessing
Women – found short term mates who are already in some relationship to be undesirable.

17. Hypotheses arising from previous slide
9) Women seeking a long term mate will prefer men who can provide resources for offspring

18. Hypotheses arising from previous slide
9) Women seeking a long term mate will prefer men who can provide resources for offspring

19. Hypotheses arising from previous slide
10) Both sexes should value attractiveness in a mate (good genes)

20. Hypothesis Proportion of cultures supporting hypothesis
Women value earning potential more than men
Women value ambition and industriousness more than men
Men value physical attributes more than women
Men value chastity more than women
Men prefer women younger than themselves
Proportion of cultures supporting hypothesis

21. Valued Disliked 3 Short term Long term -3 Physically attractive
Sexually
Experienced
Physically
unattractive
Good looking
Promiscuous
Committment
Low sex drive
No sexual Exp
Sex appeal
Prudish 3
Short term
Long term -3

22. 3 Short term Long term -3 Promising career? Good financial prospects
Likely to succeed
Reliable career
Unable to support
Poor
Uneducated
High earnings?
No ambition 3
Short term
Long term -3

23. Most primates
Males  concentration on mating effort
Females  concentration on parental effort

24. Dominance in a Social Group
Environmental constraints
Group structure
Male strategies
Female strategies

25. Dominance in a Social Group
Underlying principle:
Higher status males  more copulations
& more offspring

26. Dominance in a Social Group
Kipsigis #
wives
Acres owned

27. Dominance in Social Group
Age at puberty
Bride
price
Decade

28. Ecology of human mating systems
Starvation
Food storage/trade
Protein deficiency
Subsistence
Pathogens
Female contribution
Rain predictibility
Marriage system
Population density
Rainfall extremes
Mobility
Temperature extremes
Group size

29. Ecology of human mating systems
Starvation
Food storage/trade
Protein deficiency
Subsistence
Pathogens
Female contribution
Rain predictibility
Marriage system
Population density
Rainfall extremes
Mobility
Temperature extremes
Group size

30. Ecology of human mating systems
Starvation
Food storage/trade
Protein deficiency
Subsistence
Pathogens
Female contribution
Rain predictibility
Marriage system
Population density
Rainfall extremes
Mobility
Temperature extremes
Group size

31. Ecology of human mating systems
If there are no resources???
Unokai – Yanomami warriors (involved in a killing)
More wives earlier in life
Wives
Children
Wives
Unokai
Non-Unokai
>40
Age

32. 2. Good genes models
Fluctuating Asymmetry
Horns in oribi - Ourebia ourebia

33. Harem size
Symmetric
Asymmetric
Damaged

34. Facial Symmetry - Measurement

39. Attractiveness – Facial Symmetry
Left Mirror
Right Mirror

40. Attractiveness – Facial Symmetry

41. Symmetry and Health 1.0 Men Women 0.5 -.05 Correlation
-.05
Men
Women
Correlation
Assymetry/Health
Assymetry/Attractiveness
Health/Attractiveness

42. Symmetry and Health
Own sex faces
Opposite sex faces
Mean Health Rating
Normal
Symmetrical

43. Symmetry Preferences and Conception
Prefer Symmetry
Prefer Asymmetry
Probability of Conception

44. SPERM COMPETITION

45. Human mating systems Sperm competition How monogamous is monogamy?
Indigo bunting
Within pair
Extra-pair 12
Days before egglaying

46. Sperm Competition in Humans
Criteria
Multiple matings with different males within 5 days
-83% of women with >5 sexual partners per year report concurrence
-9% of all women & 15% of women (16-24) – concurrent relationships

47. Human mating systems Sperm competition When does it occur?
1. Adolescent courtship
Triobrand Islands

48. Human mating systems Sperm competition When does it occur?
2. Facultative polyandry
Polyandry
polyandry
polygyny
monogamy

49. Human mating systems Sperm competition When does it occur?
2. Facultative polyandry
Polyandry
polyandry
polygyny
monogamy
Facultative Polyandry
universal
moderate
occasional
uncommon

50. Human mating systems Sperm competition
Why should females be polyandrous?
1. Good genes
2. Genetic Diversity
3. Fertility Backup
- 25% of couples - sterility (35% -male)
4. Material Resources
females mate extramaritally more often with men of
higher socioeconomic status
females mate extramaritally more often with men older than their primary mate

51. Human mating systems Sperm competition
What attributes of humans may have evolved in context of sperm competition?
Males
1. Mating patterns
- most common -monogamy (with extramarital mating?)
-only if cost of any extramarital tactic is free or < cost of supporting second mate

52. Human mating systems Sperm competition
What attributes of humans may have evolved in context of sperm competition?
Males
2. Sexual Jealousy and Paternity Assurance
Spousal homocide related to sexual jealousy
USA - 33%
Africa (several studies) - 45%

53. Human mating systems Sperm competition
What attributes of humans may have evolved in context of sperm competition?
Females
1. Cryptic ovulation and continuous sexual receptivity
Most primates
Humans

54. Human mating systems Sperm competition
What attributes of humans may have evolved in context of sperm competition?
Females
2. Perennially obvious breasts

55. Central Question
Can humans be shown to mate in a manner consistent with the hypotheses surrounding mate choice by either perception of genetic quality or of ability to provide resources?
But we need to be careful in interpreting data!

56. DONE!