human mating strategies. can humans be shown to mate in a manner consistent with the hypotheses...

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


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


Men – value experience and promiscuity in short term but not long term mate

Women–experience and promiscuity not desirable in either mate


3) Men seeking a short term mate will minimize commitment and investment


Men – value commitment and investment in long term but not short term mate

Women–commitment and investment desirable in either mate


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


6) Men seeking a long term mate will solve the problem of paternity confidence

Value placed on chastity


7) Women seeking a short term mate will prefer men willing to impart immediate resources


Women – place greater importance on gift giving in a short term mate- especially negative to ‘stingy’ men


8) Women will be more selective than men in choosing a short term mate


-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.


9) Women seeking a long term mate will prefer men who can provide resources for offspring


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


Underlying principle:

Higher status males more copulations & more offspring


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

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


Sperm competition

When does it occur?

1. Adolescent courtship

Triobrand Islands


Sperm competition

When does it occur?

2. Facultative polyandry

polygyny monogamy

polyandryPolyandry


Sperm competition

When does it occur?

2. Facultative polyandry

polygyny monogamy

polyandryPolyandry

Facultative Polyandry

universal moderate occasional uncommon


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


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


Sperm competition


Males

2. Sexual Jealousy and Paternity Assurance

Spousal homocide related to sexual jealousy

USA - 33%Africa (several studies) - 45%


Sperm competition


Females

1. Cryptic ovulation and continuous sexual receptivity

Most primates Humans


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!

human mating strategies. can humans be shown to mate in a manner consistent with the hypotheses...

Documents

mate slide

previous slide

unlikely slide

female male slide

women men value commitment

women men value experience

human mating strategies

different strategies