Human Mating Strategies
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?
Central Question
1. Female investment in offspring – very high
Male investment in offspring – variable
2. Reproductive life
10 20 30 40 50 60 70 80
Female
Male
Human Reproductive Investment
3. Reproductive “down time”
10 20 30 40
Female
Human Reproductive Investment
pregnant
reproductively ‘available’
10 20 30 40 50 60 70 80
Female
Male
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
Look at sexual strategies that males and females might pursue
Look in the context of
a) short term mating
b) long term mating
Type of mating
Short-term
Long-term
Elements of male strategy Elements of female strategy
-number of partners
-identifying sexually accessible women
-minimize cost, risk, commitment
-identify women who are fertile
-paternity confidence
-assessing a woman’s reproductive value
-identify women with parenting skills
-attaining women with high quality genes
-immediate resource extraction
-evaluating short-term mates as potential long term maes
-attain men with high quality genes
-cultivate potential back-up mates
-identify men willing & able to invest
-physical protection from aggression
-identify men who will commit
-identify men with good parenting skills
-attaining men with high quality genes
Hypotheses arising from previous slide
1) Short term mating is more important for men than women
Very likely
Very unlikely
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
0Certainly
wouldProbably
wouldProbably not Certainly not
Probably/certainly not - Females - 91%
- Males - 50%
- Males
- Females
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
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
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
Age preference in mates in males and females
Hypotheses arising from previous slide
6) Men seeking a long term mate will solve the problem of paternity confidence
Value placed on chastity
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
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.
Hypotheses arising from previous slide
9) Women seeking a long term mate will prefer men who can provide resources for offspring
Hypotheses arising from previous slide
9) Women seeking a long term mate will prefer men who can provide resources for offspring
Hypotheses arising from previous slide
10) Both sexes should value attractiveness in a mate (good genes)
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
0 25 50 75 100
Good looking
Physically
unattractive
Promiscuous
Sex appeal
Sexually
Experienced
Committment
Low sex drive
Prudish
No sexual Exp
Physically
attractive
3
0
-3
Short termLong term
DislikedValued
Promising career?
Likely to succeed
High earnings?
Reliable career
Unable to support
Poor
No ambition
Uneducated
Good financial prospects
3
0
-3
Short termLong term
Most primates
Males concentration on mating effort
Females concentration on parental effort
Dominance in a Social Group
Environmental constraints
Group structure
Male strategies Female strategies
Dominance in a Social Group
Underlying principle:
Higher status males more copulations & more offspring
Dominance in a Social Group
Kipsigis
Acres owned
#wives
Dominance in Social Group
12 - 14
15 - 16
17 - 19
Age at puberty
Bride price
52-61 62-71 72-81 82-91
Decade
Ecology of human mating systems
Protein deficiency
Starvation
Subsistence
Female contribution
Marriage system
Population density
Mobility
Group size
Pathogens
Rain predictibility
Rainfall extremes
Temperature extremes
Food storage/trade
Ecology of human mating systems
Protein deficiency
Starvation
Subsistence
Female contribution
Marriage system
Population density
Mobility
Group size
Pathogens
Rain predictibility
Rainfall extremes
Temperature extremes
Food storage/trade
Ecology of human mating systems
Protein deficiency
Starvation
Subsistence
Female contribution
Marriage system
Population density
Mobility
Group size
Pathogens
Rain predictibility
Rainfall extremes
Temperature extremes
Food storage/trade
Ecology of human mating systems
If there are no resources???
Wives
Children
Unokai Non-UnokaiAge
20-24 25-30 31-40 >40
Wives
More wives earlier in life
Unokai – Yanomami warriors (involved in a killing)
2. Good genes models
Fluctuating Asymmetry
Horns in oribi - Ourebia ourebia
Symmetric Asymmetric Damaged
Harem size
Facial Symmetry - Measurement
Attractiveness – Facial Symmetry
Left Mirror Right Mirror
Attractiveness – Facial Symmetry
Symmetry and Health
Correlation
1.0
0.5
0
-.05
1.0Assymetry/Health Assymetry/Attractiveness Health/Attractiveness
MenWomen
Symmetry and Health
Mea
n H
ealt
h R
atin
g
Normal Symmetrical
Own sex facesOpposite sex faces
Prefer Symmetry
Prefer Asymmetry
Probability of Conception
0
Symmetry Preferences and Conception
SPERM COMPETITION
Human mating systems
Sperm competitionHow monogamous is monogamy?
Indigo bunting
Days before egglaying
12 0
Extra-pair
Within pair
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
Human mating systems
Sperm competition
When does it occur?
1. Adolescent courtship
Triobrand Islands
Human mating systems
Sperm competition
When does it occur?
2. Facultative polyandry
polygyny monogamy
polyandryPolyandry
Human mating systems
Sperm competition
When does it occur?
2. Facultative polyandry
polygyny monogamy
polyandryPolyandry
Facultative Polyandry
universal moderate occasional uncommon
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
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
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%
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
Human mating systems
Sperm competition
What attributes of humans may have evolved in context of sperm competition?
Females
2. Perennially obvious breasts
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?
Central Question
But we need to be careful in interpreting data!
DONE!
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