Male And Female Attractiveness

Female Attractiveness

Male and Female Attractiveness

Female Attractiveness • What sort of cues might be available to distinguish fertility? – Cues to young age (post-pubertal and pre-menopausal) • After menopause, fat distribution tends to shift and produce distinctive body type; before puberty, secondary sex characteristics are undeveloped • Smooth, unwrinkled skin tied to youth (esp in hunter-gatherer societies)

– Cues of health (lack of parasitism/disease) • No visible sores/blemishes • Whiteness of eyes • Luster/body of hair

– Sufficient energy stores • Evidence of body fat (no evidence of anorexia or malnutrition) • Body size/height

– Parity

• Clearly strong selection pressure on ancestral men to choose fertile vs. infertile females as mating partners – Especially true if males are designed for long-term mating, where investment in a single female increases costs of choosing poorly – Would expect mechanisms in male brain to look for cues related to these factors and to have preferences for those that correlate with fertility

Female Attractiveness • Even among the class of fertile women, are there cues that mark some as more chronically fertile than others? • Males who were able to distinguish these women and differentially pursue them as partners would enjoy reproductive advantage – Shorter birth spacing – Higher rates of offspring survival?

• First need to establish these individual differences in fertility do exist – Determine what causes these differences – Map what cues might be associated with fertility differences

• Not currently pregnant

Female Attractiveness

Menstrual Cycle

• Estrogen one likely candidate

Estrogen

– Estrogen (estradiol) levels are known to be decreased with: • • • •

Progesterone

Increasing age Negative energy balance Lactation/(stages of) pregnancy Stress ovulation

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Estrogen as Fertility Index

Estrogen and Fertility

• Are there physical cues that predict individual differences between women in estrogen concentrations? • Facial cues – Young women (~undergrad age, 18-24) – Facial photographs – Urine samples (for estrogen assays) • Late follicular estrogen correlated with ratings of: – Facial attractiveness (r = .48), – Femininity (r = .48), – Health (r = .52)

Lipson & Ellison (1996)

(Law-Smith et al. 2006)

WHR as possible cue to:

Estrogen as Fertility Index

Age Sex

• Are there physical cues that predict individual differences between women in estrogen concentrations?

Pregnancy status Health/Energy status Fertility (estrogen)

• Body features – Waist-to-hip ratio (WHR) • Estrogen levels are thought to influence how/where body fat is stored • More hip/thigh fat vs. abdominal (visceral) fat

– Breast size • Tissue growth influenced by presence of estrogens • Why males do not develop breasts Singh (1993)

Estrogen and Body Shape

Body Shape – Alternative to Estrogen

Polish women, 24-37 years old. Daily saliva samples for one cycle.

• Perhaps more to fat distribution than just where it is stored

Breast size and WHR split into top and bottom quartiles.

– If qualitatively different types of fat are stored at different locations on the body, then selection might favor finding certain body shapes more attractive because they contain more of specific and valuable types of fat than other body shapes – Alternative mechanism to WHR as fertility indicator argument • Both still hold that low WHR attractive because it rewards designs in male brains that seek out mates with that body shape

Jasienska 2004

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WHR and Neurodevelopment

Early Evidence for Neurodevelopment Argument

• Proposed by Gaulin; argument goes: Mother’s WHR predicts child’s IQ:

– LCFAs important for brain development • make up 20% of dry weight of brain • positive relationship between LCFA intake by mothers (prenatal vitamins associated with higher IQ in children)

– Gluteofemoral (butt and thigh) fat is primary storage site of LCFA in women (low WHR should predict high LCFA) – Most of LCFA in breast-milk comes from mothers’ fat stores instead of from current diet – LCFA are scarce in diet and have to be acquired over periods of time and then stored in gluteofemoral fat; this fat is protected and generally only used during late pregnancy and lactation

Fake it ‘till you make it • Are beauty enhancements random?

WHR increases as parity (# of births) increases:

Lassek & Gaulin (2006)

Lassek & Gaulin (2008)

Fitness Indicators and Androgens • Proposal that many traits indicate genetic quality due to their association with androgens like testosterone

– Signals of health • Symmetry, averageness (long-term) • Eyes, hair (short-term)

– Signals of fertility (estrogen-dependent) • Clear, vascularized skin • Exaggerated secondary sex characteristics • Low WHR

Testosterone Fitness Indicator in Humans? • In humans, some evidence that higher testosterone associated with more masculine facial features (Penton-Voak & Chen, 2004; Roney et al. 2006)

– Facial masculinity might be serving as a cue that can be used to estimate testosterone levels – Effects of testosterone on other features (such as secondary sex characteristics) or behaviors could also act as signal

• However, the most masculine faces not typically perceived as more attractive relative to other less masculine faces – Possible masculinity not really good cue of testosterone – Perhaps testosterone in humans does not act as fitness indicator (honest signal) – Fitness (good genes) might not be only things important in mate selection

• Testosterone appears to act as a signal that allocates energy to reproductive effort (including growth of secondary sex traits) vs. survival functions (e.g., immune responses) • Physical cues associated with higher testosterone may therefore signal that males in good enough condition to afford higher testosterone (could indicate better immune system for local environment)

Mixed Strategy Model – Females • Masculinized faces rated lower on qualities like “good father” or “quality as parent” (Johnston et al. 2001; Perrett et al. 1998)

• When choosing most “attractive” face, women generally select faces that have slightly feminized relative to the average male face (Perrett et al. 1998) – However, when women are tested near ovulation, they shift their preference toward the masculine end of the continuum (Johnston et al. 2001; Penton-Voak et al. 1999)

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The Costs of Masculinity • While masculinity might be a useful cue for estimating testosterone (which itself is a cue to good genes), it is not always found to be most attractive – Highly masculine males might be poor partners in other respects, such as in providing social support and investing resources in the relationship

Costs of Testosterone • While most studies have used masculinity, real variable of interest is testosterone – Subjects judging faces manipulated to have high vs low apparent T

Swaddle & Rierson, 2002

Other Correlates of Facial Masculinity • Thornhill & Gangestad (2006) – Men with more masculine faces self-reported fewer respiratory infections over past three years – Facial asymmetry also predicted more respiratory infections • Recall facial symmetry as index for developmental stability

• Gangestad & Thornhill (2003): – Men with more masculine faces also had more symmetrical bodies – Body symmetry another measure of developmental stability

Body Fluctuating Asymmetry • Body FA computed by measuring left and right sides of a series of traits (e.g., feet width, elbow width, ear length, etc.) and then computing overall index of asymmetry – These traits expected to be symmetrical if developmental program proceeds without problems

• No evidence that FA can itself be detected by observers – Cannot simply look at someone and estimate their FA – Observable cues may include muscularity, facial attractiveness, odor, more aggressive behaviors – all correlate with FA

• Men with lower FA report greater lifetime # of sex partners – Still true if facial attractiveness held constant

Body Fluctuating Asymmetry

Body Composition • Waist-to-chest ratio (WCR) though to be important in male attractiveness – Rough index of upper body muscularity

Suggests that men with low body FA are chosen more often by women as partners; unclear whether this is for purely sexual relations or long-term relationships Maisey et al., 1999

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Body Muscularity

Body Muscularity

• Correlated with chronic testosterone levels – If attractiveness mechanisms use facial masculinity as proxy for T, can use body muscularity as well – Should see positive relationship between muscle mass and attractiveness

Frederick & Haselton, 2007

Men’s FA and Women’s Orgasms • Some evidence that women may retain more sperm when they experience orgasm vs. when they don’t (flowback studies) – “Upsuck hypothesis”

• If so, orgasm could function as form of “cryptic female choice”: increase retention of sperm from men with indicators of good genes

Motion Cues of FA? •

Brown et al. (2005): First measured body FA in Jamaican young men and women (mean age ~ 18) – Proposed that fluidity of motion might be another cue to FA – Low FA/high quality men will have better calibrated nervous systems, muscles, etc

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Videotaped subjects dancing and used motion capture technology: subjects wore 41 infrared reflectors and 8 cameras captured the motion; computer program mapped it onto a standard animation

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Using motion capture, can isolate movement cues from physical appearance of person dancing

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Subjects watched animations and rated on scale from ‘bad dancer’ to ‘good dancer’

Men’s FA and Women’s Orgasms • Test of the theory: – Thornhill et al. (1995): measured body FA of men and recorded couples’ reports of frequency of women’s orgasm: • More frequent reports of women’s orgasm when male partner was more symmetrical • No evidence that women’s symmetry predicted their partners’ orgasm frequency • Their interpretation: some unknown cue perceived by women triggers orgasm as female choice mechanism (odor, penis morphology, something that cues body FA)

• What are alternative explanations for FA/orgasm relationship?

Physical Attractiveness Summary • Recent data suggests perceptual stimuli found attractive may not be arbitrary, but instead signal components of health and fertility – Facial symmetry and averageness as possible markers of developmental stability/heterozygosity – Face (femininity) and body shape (WHR/breast size) markers of women’s estrogen and thus likely fertility – Facial masculinity as possible marker of testosterone/immune quality – Body symmetry as further marker of developmental stability

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