“It is certainly not true that there is in the mind of Man any universal standard of beauty with respect to the human body” The Descent of Man, and Selection in Relation to Sex (p. 584) by Charles Darwin, 1871 ExamplesExamples ofof ArbitraryArbitrary CulturalCultural StandardsStandards ArbitraryArbitrary CulturalCultural StandardsStandards ArbitraryArbitrary CulturalCultural StandardsStandards BeautyBeauty isis inin thethe eyeeye ofof thethe beholder,beholder, oror isis it?it? ►►TheThe standardstandard claimclaim isis thatthat conceptionsconceptions ofof beautybeauty areare culturallyculturally determineddetermined andand thereforetherefore arbitrary.arbitrary. ►►ResearchResearch overover thethe lastlast dozendozen yearsyears oror soso revealsreveals thatthat howhow wewe evaluateevaluate beautybeauty inin thethe humanhuman bodybody appearsappears toto bebe basedbased onon aa universaluniversal setset ofof standards.standards. Therefore,Therefore, somesome conceptionsconceptions ofof beautybeauty areare notnot culturallyculturally determined.determined. WhatWhat isis Beautiful?Beautiful? RelativeRelative andand AbsoluteAbsolute StandardsStandards inin AttractivenessAttractiveness

► UniversalUniversal modelmodel:: holdsholds thatthat therethere areare absoluteabsolute standardsstandards thatthat peoplepeople useuse toto assessassess attractivenessattractiveness ► AssortativeAssortative modelmodel (like(like attractedattracted toto like):like): holdsholds thatthat standardsstandards areare relativerelative toto thethe viewer.viewer. ThatThat is,is, wewe areare attractedattracted toto thosethose whowho areare similarsimilar toto us.us. AlsoAlso knownknown asas positivepositive assortativeassortative mating.mating. ► WeWe willwill beginbegin withwith thethe universaluniversal (or(or absolute)absolute) andand followfollow withwith thethe assortativeassortative (or(or relative)relative) ► Finally,Finally, mostmost ofof thethe researchresearch hashas focusedfocused onon femalefemale attractivenessattractiveness UniversalUniversal basesbases forfor femalefemale physicalphysical attractivenessattractiveness ¾General ƒSymmetry: low fluctuating asymmetry (applies to males also) ¾Body form ƒWaist to hip ratio of approximately 0.7 (?) ¾Face ƒAverage (applies to males also) ƒsmall lower jaw (nasion to chin) ƒhigh upper and lower lips ƒsmall mouth (width) ƒlarge eyes ƒlight skin ƒhomogenous skin texture SymmetrySymmetry HowHow symmetrysymmetry isis measuredmeasured SymmetrySymmetry measures:measures: 11 SymmetrySymmetry measures:measures: 22 SymmetrySymmetry measures:measures: 33 SymmetrySymmetry measures:measures: 44 SymmetrySymmetry measures:measures: ““What?What? MeMe Worry?Worry?”” PhysicalPhysical developmentdevelopment andand symmetrysymmetry areare regulatedregulated by:by: ƒgrowth rates ƒhormone levels ƒnutrition ƒdisease 9The level of symmetry is a measure of developmental stability. 9Developmental stability is an indication of an individual's ability to withstand genetic and environmental stress during growth. 9High FA is very weakly and perhaps inconclusively associated with increased morbidity and decreased heterozygosity 9It may be the case that modern medicine has broken the relationship between symmetry and health. Research needs to be done on populations with poor access to health care to evaluate the utility of symmetry as a sign of fitness. SymmetrySymmetry isis positivelypositively associatedassociated withwith ► StatureStature ƒ Tall males less asymmetrical (positive association) ƒ Small females less asymmetrical (negative association) ► IQIQ ► NumberNumber ofof lifetimelifetime partnerspartners andand RSRS (males(males && females)females) ► RunningRunning speedspeed ► AggressionAggression ► DepressionDepression

Source: JT Manning et al., 2002, Evolution and Human Behavior FacialFacial AveragenessAverageness

“Attractive faces are only average”. Langlois & Roggman. Psychological Science (1990) ComputingComputing AveragenessAverageness

Source: The Evolutionary Psychology of Facial Beauty. Annual Review of Psychology (2006) Gillian Rhodes Examples:Examples: creatingcreating anan averageaverage faceface (Asian)(Asian) CreatingCreating anan averageaverage faceface (N.(N. Amer.)Amer.) AverageAverage plusplus reducereduce jawjaw andand peakedpeaked lipslips leadsleads toto anan eveneven moremore attractiveattractive faceface

Length of nasion to chin in red to indicate smaller lower face. AveragenessAverageness isis associatedassociated withwith

high levels of heterozygosity which, in turn, is associated with enhanced pathogen resistance. That is, average looking people tend to be healthier. But the effect is very moderate and needs further study. OtherOther FactorsFactors AssociatedAssociated withwith AttractivenessAttractiveness

►►FacialFacial SmoothnessSmoothness ►►SkinSkin colorationcoloration ►►SpecificSpecific facialfacial featuresfeatures FacialFacial smoothness:smoothness: absenceabsence ofof blemishesblemishes andand lineslines indicativeindicative ofof youth.youth. InIn addition,addition, skinskin darkensdarkens withwith age.age.

Subject on left retouched to enhance facial homogeneity MaleMale andand FemaleFemale DifferencesDifferences inin SkinSkin ColorColor ►►MenMen areare darkerdarker thanthan womenwomen ƒƒ ResultResult ofof heavierheavier concentrationconcentration ofof hemoglobinhemoglobin inin bloodblood andand melaninmelanin inin skinskin andand thickerthicker subcutaneoussubcutaneous fatfat layerlayer inin womenwomen ƒƒ Universally,Universally, menmen preferprefer womenwomen whowho areare lighterlighter thanthan averageaverage (relative(relative toto locallocal population)population) andand womenwomen preferprefer menmen whowho areare darkerdarker thanthan averageaverage (relative(relative toto locallocal population).population). ƒƒ ButBut oneone cancan bebe tootoo darkdark oror tootoo lightlight inin locallocal populationpopulation SkinSkin ColorColor andand AttractivenessAttractiveness

►►FrostFrost reportsreports thatthat outout ofof 5151 differentdifferent culturescultures inin thethe HRAF,HRAF, 4444 culturescultures favoredfavored lighterlighter complexionscomplexions onon eithereither onlyonly womenwomen (30)(30) oror onon bothboth sexessexes (14).(14). InIn onlyonly 33 culturescultures waswas fairfair skinskin preferredpreferred onon menmen only,only, andand inin justjust 44 culturescultures waswas darkerdarker skinskin desireddesired inin women.women. MaleMale Attractiveness,Attractiveness, Masculinity,Masculinity, andand SpecificSpecific FacialFacial FeaturesFeatures

► ProminentProminent cheekcheek bonesbones andand longerlonger lowerlower facesfaces areare bothboth judgedjudged asas attractiveattractive inin males.males. ► WhenWhen thesethese twotwo factorsfactors areare combinedcombined aa masculinitymasculinity indexindex isis created,created, andand thisthis indexindex isis moremore stronglystrongly correlatedcorrelated withwith attractivenessattractiveness thanthan cheekbonecheekbone oror longerlonger lowerlower faceface alone.alone. ► Finally,Finally, malemale facialfacial symmetrysymmetry andand thethe masculinitymasculinity indexindex werewere correlated.correlated.

Source: Scheib, Gangstead, and Thornhill “Facial attractiveness, symmetry and cues of good genes. Proc. R. Soc Lond. B (1999) FeminineFeminine andand MasculineMasculine FacesFaces

►►MalesMales favorfavor womenwomen withwith femininefeminine facesfaces ƒƒ SmallSmall chinchin andand highhigh cheekcheek bonesbones ƒƒ FullerFuller andand moremore peakedpeaked lipslips ƒƒ LargeLarge eyeseyes (relative(relative toto face)face) ►►FemalesFemales favorfavor malesmales whowho areare slightlyslightly toto moderatelymoderately faciallyfacially masculinemasculine butbut notnot extremelyextremely soso ƒƒ ChinsChins broaderbroader andand longerlonger ƒƒ LargeLarge browbrow ridgeridge BodyBody Form:Form: WaistWaist toto hiphip ratioratio

WHR is a reliable index of age, hormonal status, parity, fecundity, and health. Before puberty boys and girls have similar ratios. However, with females pelvis widens and fat is deposited on hips and thighs at puberty. Healthy women have ratios of 0.67 to 0.80 while healthy men have 0.80 to 0.95. For attractiveness, ideal for men is 0.90 and female ideal is 0.7 (for Western populations only). WaistWaist toto HipHip Ratio:Ratio: standardstandard stimulusstimulus setset WHRWHR andand femalefemale matemate valuevalue

WHR increases with each pregnancy and increases slightly with age. However, a 17 year old will have nearly the same WHR as a 22 year woman and at menopause it reaches the level of a male's WHR (about 1). High WHR is strongly negatively associated with the probability of conception and positively associated with age. MaleMale andand femalefemale evaluationsevaluations areare parallelparallel butbut malesmales placeplace greatergreater emphasisemphasis onon WHRWHR

Streeter, S.A. & McBurney, D.H. (2003) Waist– hip ratio and attractiveness: New evidence and a critique of "a critical test", Evolution and Human Behavior, 24, 88-98. WHRWHR ratioratio andand healthhealth correlatescorrelates

High WHR in women is a sign of: • menstrual irregularity • hirsutism (abnormal growth & distribution of hair) • elevated plasma triglycerides • diabetes and insulin intolerance • hypertension •stroke • gall bladder disease • reproductive cancers (endometrial, ovarian, and breast) WHRWHR andand BehavioralBehavioral CorrelatesCorrelates inin WomenWomen

►►PositivelyPositively correlatedcorrelated withwith ageage ofof firstfirst intercourse.intercourse. ►►NegativelyNegatively correlatedcorrelated withwith numbernumber ofof lifelife-- timetime sexualsexual partnerspartners andand EPCEPC’’s,s, Examples:Examples: bothboth figuresfigures havehave aa 0.70.7 WHRWHR (the(the moremore thingsthings change,change, thethe moremore theythey staystay thethe same)same) FurtherFurther exampleexample ofof WHRWHR’’ss WHRWHR ofof 0.70.7 aa reflectionreflection ofof WesternWestern standards?standards?

► Recent research by anthropologists reveals that a WHR ratio of about 0.8 is preferred in the following ethnic groups: ƒ Hadza ƒ Shuar ƒ Machiguenga ► Greater than 0.7 WHR may be a consequence of living in a food short environment which suggests that men are concerned with energy status when it is relevant (i.e., not relevant in the West but relevant in tribal populations) ► BMI: additional research in the West suggests that BMI is more important. The problem with BMI and WHR is that they are strongly correlated with each other. Thus, it is unclear which is the signal of reproductive potential. BMI/WHRBMI/WHR Brits & SA Zulus andand CultureCulture

“Changing perceptions of Brit Zulu & attractiveness as SA Zulus observers are exposed to a different cultures” B. Martin J. Toveé et al. Evolution and Human Behavior (2006)

Brits of African Origin & Brit Zulus LocalLocal conditionsconditions maymay mattermatter Poverty & Hunger: People in rural South Africa are living in a low-resource, economically deprived society. Fifty-six percent report going hungry, and most households do not have electricity, running water, or significant amounts of household durable goods. In South Africa a higher female body weight is perceived to reflect affluence, high status, and good health. It is therefore not surprising that our results suggest that a higher female BMI is regarded as attractive. Health Problems: These preferences may be reinforced by the current health problems prevalent in South Africa. There are long-standing problems with infectious diseases, including lower respiratory tract infections, meningitis, diarrhea, septicemia and TB, which, when combined with low levels of immunization, make potential infection a serious possibility. The health consequences linked to these serious diseases include weight loss, and this is reflected in the perception that a lower body mass may signal potential parasitic infection or disease SHR:SHR: shouldershoulder toto hiphip ratioratio anan introductionintroduction toto aa malemale signsign ►►Measurement:Measurement: ƒƒ hiphip measuredmeasured asas largestlargest circumferencecircumference aroundaround thethe hipships andand buttocks.buttocks. ƒƒ ShoulderShoulder measuredmeasured asas greatestgreatest widthwidth ofof shouldshould bladesblades withwith armsarms atat sides.sides. ►►Results:Results: ƒƒ MenMen rangedranged fromfrom 1.031.03 -- 1.40,1.40, meanmean ofof 1.181.18 ƒƒ WomenWomen rangedranged fromfrom 0.90.9 -- 1.22,1.22, meanmean ofof 1.031.03

SHR 1 of 2 SHRSHR inin men:men: behavioralbehavioral correlatescorrelates

►►NegativelyNegatively correlatedcorrelated withwith ageage atat firstfirst sexualsexual intercourseintercourse (narrow(narrow shoulders=latershoulders=later firstfirst sex)sex) ►►PositivelyPositively correlatedcorrelated with:with: ƒƒ reportedreported numbernumber ofof sexualsexual partners;partners; andand ƒƒ EPCEPC (extra(extra pairpair copulations)copulations) oror cheatingcheating onon youryour ownown partnerpartner (broad(broad shoulders=moreshoulders=more sex)sex)

SHR 2 of 2 HeightHeight andand AttractivenessAttractiveness

► InIn thethe westwest malesmales preferprefer femalesfemales whowho areare shortershorter thanthan averageaverage whilewhile femalesfemales preferprefer malesmales whowho areare tallertaller thanthan average.average. ► InIn thethe westwest talltall menmen havehave higherhigher RSRS thanthan shortershorter malesmales andand shortershorter femalesfemales havehave higherhigher RSRS thanthan tallertaller females.females. ► ButBut inin ruralrural GambiaGambia thisthis relationshiprelationship seemsseems notnot toto hold.hold. ƒ Tall women had higher fertility & higher survivorship of their children ƒ While taller men were only very slightly more likely to have higher RS than shorter men

Sear “Height and Reproductive Success”. Human Nature 17(4) 2006. HeightHeight inin GambiaGambia

► InIn GambiaGambia talltall womenwomen areare moremore reproductivelyreproductively successfulsuccessful (higher(higher fertility)fertility) thanthan shortshort women.women. ► ThereThere isis nono correlationcorrelation betweenbetween heightheight andand fertilityfertility amongamong men.men. ► However,However, tallertaller menmen contractcontract moremore marriagesmarriages thanthan shortershorter men.men. ► NoNo correlationcorrelation betweenbetween heightheight andand healthhealth forfor GambianGambian menmen andand ► forfor GambianGambian womenwomen thethe relationshiprelationship isis invertedinverted UU-- shaped.shaped.

Sear “Height and reproductive success: how a Gamian population compares to the West” (2005) AssortativeAssortative oror relativerelative models:models: ““SelfSelf seekingseeking likelike””

► PeoplePeople marrymarry thosethose whowho resembleresemble themselvesthemselves ► KnownKnown asas positivepositive assortativeassortative matingmating ► CorrelationsCorrelations forfor mostmost physicalphysical traitstraits (height,(height, weight,weight, hairhair color,color, etc.)etc.) andand manymany behavioralbehavioral traitstraits (interests,(interests, personality,personality, etc)etc) ► TwoTwo potentialpotential explanationsexplanations forfor thisthis relationship:relationship: ƒ Optimizes outbreeding to avoid excessive genetic variance that would interfere with coadaptive gene complexes ƒ Competition and matching hypotheses

Self seeking 1 of 2 SelfSelf perceptionperception andand matemate choicechoice inin WesternWestern societysociety

►►TheThe standardstandard evolutionaryevolutionary argumentargument isis thatthat menmen areare attractedattracted toto beauty,beauty, youthfulness,youthfulness, sexualsexual fidelity,fidelity, andand healthhealth whilewhile ►►WomenWomen areare attractedattracted toto menmen whowho areare ambitious,ambitious, wealthywealthy andand havehave highhigh socialsocial statusstatus ►►ButBut asas MickMick andand KeithKeith notenote ““YouYou cancan’’tt alwaysalways getget whatwhat youyou wantwant””

Self perception and mate choice in Western society: Buston and Emlen PotentialsPotentials attractattract

►►ThisThis hashas ledled manymany toto successfullysuccessfully predictpredict thatthat matemate choicechoice wouldwould bebe basedbased onon reproductivereproductive potentialpotential.. ThatThat isis ►►attractiveattractive women,women, forfor example,example, wouldwould matchmatch upup withwith wealthywealthy men.men. ►►TheThe problemproblem withwith thisthis argumentargument isis thatthat itit ignoresignores thethe problemproblem ofof stabilitystability inin marriage,marriage, aa keykey toto RSRS

Self perception and mate choice in Western society: Buston and Emlen MaritalMarital StabilityStability

►►IfIf matemate choicechoice werewere basedbased onon reproductivereproductive potentialpotential thenthen ƒƒ ReproductionReproduction mightmight bebe delayeddelayed waitingwaiting forfor anan exceptionallyexceptionally beautifulbeautiful oror wealthywealthy mate.mate. ƒƒ Furthermore,Furthermore, thesethese marriagesmarriages wouldwould bebe unstableunstable ifif aa moremore beautifulbeautiful oror moremore wealthywealthy matemate camecame along.along. OneOne wouldwould bebe temptedtempted toto ““tradetrade upup””..

Self perception and mate choice in Western society: Buston and Emlen RelativismRelativism inin matemate choicechoice

►►WomenWomen lowerlower theirtheir selfself--assessedassessed beautybeauty whenwhen exposedexposed toto beautifulbeautiful womenwomen andand menmen lowerlower theirtheir selfself--assessedassessed attractivenessattractiveness whenwhen exposedexposed toto sociallysocially dominantdominant males.males. ►►InIn addition,addition, eacheach sexsex lowerslowers theirtheir assessmentassessment ofof thethe otherother whenwhen theirtheir matesmates werewere comparedcompared toto moremore highlyhighly ratedrated membersmembers ofof thethe oppositeopposite sexsex

Self perception and mate choice in Western society: Buston and Emlen TheThe questionquestion

► PotentialsPotentials attract:attract: areare choiceschoices basedbased onon absoluteabsolute criteriacriteria (e.g.,(e.g., beautybeauty andand wealth)?wealth)? oror dodo ► likeslikes attract,attract, aa relativerelative criteria:criteria: howhow similarsimilar areare theythey toto thethe seekerseeker inin aa numbernumber ofof crucialcrucial dimensions?dimensions? ► TenTen questionsquestions askedasked thatthat cancan bebe divideddivided intointo 44 evolutionaryevolutionary categories:categories: ƒ Wealth and status ƒ Physical attractiveness ƒ Fidelity ƒ Family commitment

Self perception and mate choice in Western society: Buston and Emlen ResultsResults II

►►IfIf thethe potentialspotentials modelmodel isis correctcorrect thenthen attractiveattractive womenwomen wouldwould havehave hadhad strongerstronger preferencespreferences forfor wealthierwealthier menmen andand vicevice versaversa ►►ThisThis patternpattern waswas observedobserved toto bebe statisticallystatistically significantsignificant butbut itit explainedexplained veryvery littlelittle ofof thethe variancevariance (around(around 5%)5%)

Self perception and mate choice in Western society: Buston and Emlen ResultsResults IIII

►►IfIf thethe likeslikes attractattract thenthen therethere shouldshould bebe aa positivepositive correlationcorrelation betweenbetween selfself perceptionperception (e.g.,(e.g., fidelityfidelity oror attractiveness)attractiveness) andand importanceimportance ofof thatthat samesame factorfactor inin aa mate.mate. ►►ThisThis patternpattern waswas foundfound andand thethe correlationscorrelations werewere muchmuch stronger:stronger: ~35%~35% forfor womenwomen andand ~12%~12% forfor men.men.

Self perception and mate choice in Western society: Buston and Emlen ConclusionsConclusions

►►HumanHuman matemate choicechoice inin WesternWestern societysociety seemsseems toto bebe moremore stronglystrongly basedbased onon preferencepreference forfor longlong--termterm partnerspartners whowho areare similarsimilar toto oneone’’ss perceptionperception ofof selfself acrossacross aa numbernumber ofof evolutionarilyevolutionarily relevantrelevant categoriescategories ofof traits.traits.

Self perception and mate choice in Western society: Buston and Emlen AA FinalFinal ThoughtThought onon Beauty,Beauty, Similarity,Similarity, andand MateMate ChoiceChoice

► In the EEA potential mates are in short supply because females tend to be married immediately after puberty. ► Furthermore, the pool of potential mates is very small relative to modern populations ► Consequently, to maximize fitness males must marry the first available female or face the consequence of delayed competition. ► This makes choice based on beauty or similarity difficult, or impossible.