Mate Preferences

Survey Research • What characteristics do men and women want in a romantic partner? Do they want the same things or different things?

Human Mate Preferences • Early research methods:

• Buss (1989): Subjects from 37 different cultures rated and ranked lists of attributes for their desirability in choosing a mate.

Buss (1989) • Uses Parental Investment (PI) theory to generate hypotheses regarding sex differences in mate preferences • “The sex investing more in offspring will be selected to exert stronger preferences about mating partners” – Are costs of bad mate choice greater for men or women? (ancestral) – Are benefits of indiscriminate mating likely to be greater for men or women?

Implicit assumptions • Buss (implicitly) extends PI theory to predict broadly different sexual strategies for men and for women – Men generally will follow short-term mating strategy (STM) in which they pursue sexual access with a number of partners over commitment to a single partner – Women generally will follow long-term mating strategy (LTM) in which they seek commitment and investment from a single partner

Implicit Assumptions

What should (choosy) women want? • Buss: In species with “ability and willingness to provide resources related to parental investment” (parental investment)

• While these predictions probably have some truth to them, the reality is likely to be more complicated: – Careful thinking about the evidence suggests reasons why this view is incorrect – To be fair - current articulation of the sexual strategies model is more complex than that presented above

• Ancestral women likely could not have had more than ~ 10 children in a lifetime – Variance in women’s reproductive success thus in part depend on what fraction of 10 kids survived and reproduced – Genes that led to choices of mates that caused greater fraction of kids to survive and reproduce should have spread in population

• Men’s provisioning of food, shelter, territory, protection could have increased survival rates of women’s offspring • Hypothesis: “Females, more than males, should value attributes in potential mates such as ambition, industriousness, and earning capacity”

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Resources Hypothesis 1: “Females should seek to mate with males who have the ability and willingness to provide resources . . . Such as food, shelter, territory, and protection.” Prediction 1: “Females, more than males, should value attributes in potential mates such as ambition, industriousness, and earning capacity that signal the possession or likely acquisition of resources.”

Characteristic: “Good financial prospect” 0 (unimportant) to 3 (indispensable)

USA

males

females

1.08

1.96

36 out of 37 countries sig.

Preference for Physical Attractiveness • Does a stronger male (vs. female) preference for physical attractiveness directly follow from parental investment theory? – Holding constant age, should men prefer more attractive to less attractive women? – As long as women are young adults (post-pubertal, pre-menopausal) and relatively healthy, does PI theory predict that attractiveness will make a difference?

What should men want? • From PI theory: “For males more than females, reproduction is limited by access to reproductively valuable or fertile mates.” • Female fertility is strongly age-graded: zero until puberty and after menopause, increasing from puberty until mid- to late- twenties, declining by mid-thirties • Male fertility is not nearly as strongly age-graded • Female fertility is though to be indexed by physical attractiveness

• Hypothesis: “Males, more than females, will value relative youth and physical attractiveness in potential mates because of their links with fertility and reproductive value”

Physical Attractiveness across Species • In polygynous species with large sex differences in parental investment: – Males display physical attractiveness to females and females choose based on it – Males are unselective between reproductively mature females of same species

• In a STM strategy, maximization of # of matings is more important than quality of matings

• First principle from PI theory: women should be choosier than men • Think carefully: If men are designed for short-term mating, what should their preferences look like? Should they care about physical attractiveness?

Human Preferences for Attractiveness • Importance of physical attractiveness to males: – Male parental investment in offspring during long-term mating makes choice of attractive mate important if attractiveness predicts variance in fertility/offspring quality over time • If attractiveness provides clues about where women will be on fertility continuum, makes sense to desire high levels of it • Since choosing for long-term relationship (and investment), costs of making a poor choice are magnified

– Energetic costliness of producing large-brained human infants may have increased variance in human female fertility relative to other species

• A strong preference for physical attractiveness only makes sense if men are seeking long-term mates with whom they may have multiple offspring over time

Human Preferences for Attractiveness • Why don’t females care as much about physical attractiveness in males? – Since males provide more than just genes to offspring, females should also weight resource provisioning and not just cues of genetic quality

• Explains inversion in importance of physical attractiveness in humans relative to other species

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Physical Attractiveness Hypothesis 2: “Males should prefer attributes in potential mates associated with reproductive value or fertility, . . .” Prediction 2: “Males, more than females, will value relative youth and physical attractiveness in potential mates because of their links with fertility and reproductive value.”

Characteristic: “Good looks” 0 (unimportant) to 3 (indispensable)

USA

males

females

2.11

1.67

34 out of 37 countries sig. (37/37 males >)

• Reproductive Value: Expected future reproduction (peaks in mid-teens then declines steadily) • Fertility: Probability of present reproduction (peaks in early to mid-20’s then declines) • So STM will predict that men find women in their early- to mid-twenties to be of optimal attractiveness

Preference for Youth

Youth Hypothesis 2: “Males should prefer attributes in potential mates associated with reproductive value or fertility, . . .” Prediction 2: “Males, more than females, will value relative youth and physical attractiveness in potential mates because of their links with fertility and reproductive value.”

Characteristic: “Age difference preferred . . .” negative prefers younger mate; positive prefers older mate

Mean

Preference for Youth

males

females

-2.66

3.42

• “if males in our evolutionary past have tended to seek short-term mating partners, selection should have favored male preferences for females in their early 20’s” • “subtracting the mean age difference preferred between males and their mates (2.66 years) from the age at which males prefer to marry (27.49 years), it can be inferred that males in these samples prefer to marry females who are approximately 24.83 years old.” • Does this result support the idea that men are designed for shortterm mating (STM) that maximizes current fertility?

37 out of 37 countries

Interpretation of Youth Data • Symons commentary: – Prediction is that men will be most strongly sexually attracted to women with cues of high reproductive value (age want to marry may be influenced by other things) – “By 25 years of age, most tribal women have had two or three children, and the evidence of childbearing, nursing, and rearing is clearly manifested in their bodies” – Women in modern societies maintain youthful appearance much longer – Predicts that even western men would find late teenage women (without kids) in hunter-gatherer most sexually attractive: if so, sexual attraction mechanisms may in fact be responding to cues of reproductive value > cues to fertility

Mixed Strategies in Men? • Trivers (1972): “In species where there has been strong selection for male parental care, it is more likely that a mixed strategy will be the optimal male course – to help a single female raise young, while not passing up opportunities to mate with other females whom he will not aid.” • May explain why men still fantasize about multiple partners, more eager for sex w/o commitment, etc. Situation different for women. • Trivers: “…A male would be selected to differentiate between a female he will only impregnate and a female with whom he will also raise young. Toward the former he should be more eager for sex and less discriminating in choice of sex partner than the female toward him, but toward the latter he should be about as discriminating as she toward him.”

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Mixed Strategies in Men?

Alternative Explanation • Eagly & Wood (1999) have different interpretation: – Does not rely on PI theory as a framework for making predictions – PI posits differences in cognitive architectures should develop between sexes (men and women face different selection pressures in mate selection), and some people don’t like differences…

Kenrick et al. (1990)

Eagly and Wood (1999) Buss

• How do Eagly & Wood explain the cross-cultural patterns of sex differences in mate preferences identified by Buss? • Distribution of jobs in economy causes people to develop personalities/preferences to accommodate to job roles: “gender roles by which people of each sex are expected to have characteristics that equip them for the tasks they typically carry out.” – Females prepare for nurturing domestic roles and males for agentic occupational roles – Mate preferences accommodated to these job roles: females seek good providers, males seek domestic skills

Early hormone exposure Genes

Nonhuman species: female rats injected with testosterone during perinatal period (experience controlled): – Develop aggressive behavioral styles of male rats (juvenile play fighting) – Adopt male spatial navigation strategies (use landmarks less vs. geometric cues) – Ferrets with early hormone manipulations will change sex preferences to samesex

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Congential adrenal hyperplasia (CAH) – Increases prenatal androgen exposure in humans – Evidence that CAH girls have more male play styles (rough and tumble, less interest in dolls) – CAH girls higher (more male-like) scores on spatial tests such as mental rotation test – Some evidence for greater rates of homosexuality and bisexuality in CAH girls, though most report being heterosexual – Do not see principled difference in employment/social roles

M-F Different Brain structures

M-F Different mate preferences

?? E&W Early hormone exposure Genes

Distinct roles/jobs in economy M-F Same Brain structures

M-F Different mate preferences

“We acknowledge that the social structural perspective does imply that differences in the minds of women and men arise primarily from experience and socialization, …”

Evidence for Hormonal Influences on Brain Mechanisms/Behavior •

Contextual input

Eagly & Wood on Mate Preferences • Resources/Earning capacity: – – – –

Given the male provider/female home-maker division of labor: Women “maximize their outcomes” by seeking financial success in mate Men “maximize their outcomes” by seeking mate good in domestic role What meant by “maximize outcomes?” (money, happiness?)

• Age differences: – “…combination of a younger, less experienced woman and an older, more experienced man, it would be easier to establish the power differential favoring men that is normative for marital roles defined by a male bread-winner and a female domestic worker.” – Men want young women so they can have power over them in order to have a harmonious division of labor

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Eagly & Wood on Mate Preferences

Eagly & Wood on Mate Preferences

• General prediction: As gender roles become more similar in more gender equal societies, sex differences in mate preferences should decrease – Women have more income, less need to acquire it through marriage – Men’s preference for younger women should decrease as women take on more occupational roles

• Assigned estimates of gender equality to each of Buss’ 37 samples using published measures of countries’ level of female participation in economic and political life • Correlation between gender equality measures and sex differences predicted to be negative across countries

Why do some results correlate with gender equality measures? • Age differences: – In some of Buss’ 37 cultures, men are legally allowed to marry teenage girls • Are those cultures the ones with the greatest degree of gender equality? How would that be expected to affect results?

– Does negative correlation between age preference and gender equality imply that men do not have mechanisms that find physical cues associated with youth sexually attractive?

Eagly & Wood – further predictions • General problem that answers to a survey may reflect more than the output of mate preference mechanisms: – Social norms – Economic and other considerations

• Financial resources: – In some poorer countries, women may be unable to earn enough income to survive on their own: marriage to a husband with earning capacity may be matter of survival – Such women may not marry men they find most attractive: attraction mechanisms may be universal, which may be obscured by practical considerations

Eagly & Wood – further predictions • If true, should not see income/mate preference shifts within societies – In U.S., women who have higher incomes found to have stronger preferences for high income in mates, not weaker • why not seek husband who is good housekeeper? Or physically attractive?

• Correlations with gender equality may arise because other factors associated with economic development may affect how people answer questions

Problems with Survey Data • Correlations with gender equality may arise because survey questions imperfectly estimate functioning of mate preference mechanisms • Notice: a similar criticism applies to Buss findings also – No description of mate preference mechanisms – At best, estimates mechanism output

– Eagly and Wood argue that this is product of homogamy: tendency to marry from own socieconomic stratum • why does this happen?

– Which group of individuals tends to marry out of their socioeconomic group?

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Mate Preferences – minimum acceptable percentiles

Mate Preferences - Ranking

Kenrick 1990 data

Physical attractiveness

Earning capacity

Kind and understanding

Intelligence (Buss & Barnes, 1986)

Self-Report Surveys • Although physical attractiveness and resource provisioning preferences show sex differences, neither is rated very important by either sex (near middle or bottom of ranking lists)

Kindness? • Is kindness actually more important than resources, physical attractiveness, etc.? • Target of kindness matter? – Kindness to self – Kindness to others/strangers

• Kind-understanding and Intelligent rated consistently most important by both men and women across many studies • Question: are the most kind and intelligent people the most desirable as potential mates?

Intelligence

• Possible that people choose partners based on other characteristics, but then desire more kindness in partners once chosen? • Kindness only attractive if combined with other traits? – Wimpy and kind preferable to strong and less kind? – Issue of trait combination not addressed by self-report surveys

Schematic Model of Specialized Mechanisms Morphological Cues

Self-report surveys: men rate intelligence much higher than physical attractiveness What if cues to very high attractiveness but also very low intelligence? Men find it unattractive?

Behavioral patterns (kindness, status, r possession) Brain structures

Behavioral output

Problem for Self-Report Surveys: Input-output mapping may occur without subjects having conscious access to what properties made them attracted to someone else

Feelings of attraction Courtship behaviors Receptivity cues (smiling)

Surveys test our theories about our mate preferences and those theories may be wrong How do we get around these issues and investigate the mechanisms themselves?

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