Human Mating
Strategies
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?
Human Reproductive Investment
1. Female investment in offspring – very high
Male investment in offspring – variable
2. Reproductive life
Female
Male
10
20
30
40
50
60
70
80
Human Reproductive Investment
3. Reproductive “down time”
pregnant
reproductively ‘available’
Female
10
20
30
40
Female
Male
10
20
30
40
50
60
70
80
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
-immediate resource extraction
-identifying sexually accessible
women
-evaluating short-term mates as
potential long term maes
-minimize cost, risk, commitment
-identify women who are fertile
-attain men with high quality genes
-cultivate potential back-up mates
-paternity confidence
-identify men willing & able to invest
-assessing a woman’s reproductive
value
-physical protection from aggression
-identify women with parenting
skills
-identify men who will commit
-identify men with good parenting
skills
-attaining women with high quality
genes
-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
Probably/certainly not
- Females - 91%
- Males - 50%
80
- Males
60
- Females
40
20
0
Certainly
would
Probably
would
Probably not
Certainly not
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
0
25
50
75
100
Proportion of cultures supporting hypothesis
Valued
3
0
Short term
Long term
-3
Disliked
3
0
Short term
Long term
-3
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
#
wives
Acres owned
Dominance in Social Group
Age at
puberty
12 - 14
15 - 16
17 - 19
Bride
price
52-61
62-71
72-81
Decade
82-91
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
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
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
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
20-24
25-30
Age
31-40
>40
2. Good genes models
Fluctuating Asymmetry
Horns in oribi - Ourebia ourebia
Harem size
Symmetric
Asymmetric
Damaged
Facial Symmetry - Measurement
Attractiveness – Facial Symmetry
Left Mirror
Right Mirror
Attractiveness – Facial Symmetry
Symmetry and Health
1.0
Men
Women
0.5
0
Correlation
-.05
1.0
Assymetry/Health
Assymetry/Attractiveness
Health/Attractiveness
Mean Health Rating
Symmetry and Health
Own sex faces
Opposite sex faces
Normal
Symmetrical
Symmetry Preferences and Conception
Prefer Symmetry
0
Prefer Asymmetry
Probability of Conception
SPERM COMPETITION
Human mating systems
Sperm competition
How monogamous is monogamy?
Indigo bunting
Within pair
Extra-pair
0
12
Days before egglaying
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
polyandry
Polyandry
polygyny
monogamy
Human mating systems
Sperm competition
When does it occur?
2. Facultative polyandry
polyandry
Polyandry
monogamy
polygyny
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
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!
DONE!