lecture 20: fatness & the fat: where is it...
TRANSCRIPT
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Lecture 20: Fatness & the Lecture 20: Fatness & the
Female BodyFemale Body
•• FAT FAT —— what is it for?what is it for?
•• BreastsBreasts
•• Female Body ImageFemale Body Image
•• WaistWaist--Hip RatioHip Ratio
•• Eating DisordersEating Disorders
Behavioral Biology of Women-2007
Fat: Where is it Stored?Fat: Where is it Stored?
(Pond, 1997)
““FactsFacts”” about Fatabout Fat
•• Humans are particularly Humans are particularly
fat among primatesfat among primates
““FactsFacts”” about Fatabout Fat
•• Humans are Humans are
particularly fat particularly fat
among primatesamong primates
•• Women between 16 Women between 16
and 18, 26and 18, 26--28% 28%
body fat.body fat.
““FactsFacts”” about Fatabout Fat
•• Humans are particularly Humans are particularly
fat among primatesfat among primates
•• Women between 16 and Women between 16 and
18, 2618, 26--28% body fat.28% body fat.
•• Men between 16 and 18, Men between 16 and 18,
14% body fat14% body fat
““FactsFacts”” about Fatabout Fat
•• Humans are particularly fat Humans are particularly fat
among primatesamong primates
•• Women between 16 and 18, Women between 16 and 18,
2626--28% body fat.28% body fat.
•• Men between 16 and 18, 14% Men between 16 and 18, 14%
body fatbody fat
•• Estrogen promotes deposition Estrogen promotes deposition
of fat on hips and thighsof fat on hips and thighs
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““FactsFacts”” about Fatabout Fat
•• Humans are particularly Humans are particularly fat among primatesfat among primates
•• Women between 16 and Women between 16 and 18, 2618, 26--28% body fat.28% body fat.
•• Men between 16 and 18, Men between 16 and 18, 14% body fat14% body fat
•• Estrogen promotes Estrogen promotes deposition of fat on hips deposition of fat on hips and thighsand thighs
•• Fat is laid down at Fat is laid down at puberty and during puberty and during pregnancypregnancy
Why are humans so fat?Why are humans so fat?
•• Energy depletionEnergy depletion
•• ReproductionReproduction
•• BrainBrain
(1) Fat as Protection against (1) Fat as Protection against
Energetic DepletionEnergetic Depletion
•• Humans have a high propensity to store fatHumans have a high propensity to store fat
–– Buffer against periods of low food availabilityBuffer against periods of low food availability
(1) Fat as Protection against (1) Fat as Protection against
Energetic DepletionEnergetic Depletion
•• Humans have a high propensity to store fatHumans have a high propensity to store fat
–– Buffer against periods of low food availabilityBuffer against periods of low food availability
•• Periods of low food availability may have Periods of low food availability may have
been common during human evolutionbeen common during human evolution
Famines in PreFamines in Pre--Industrial SocietiesIndustrial SocietiesSelection for Fatness in SamoansSelection for Fatness in Samoans
0
10
20
30
40
50
60
70
80
90
100
Percentage of Women
Overweight
20-24 25-34 35-44 45-54 55-64 65-74
Western Samoa Hawaii(McGarvey 1991)
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0
10
20
30
40
50
60
70
80
90
100
Percentage of Women
Overweight
20-24 25-34 35-44 45-54 55-64 65-74
Western Samoa Hawaii
(McGarvey 1991)
Selection for Fatness in SamoansSelection for Fatness in Samoans
•• Selection for fat Selection for fat storage (storage (‘‘Thrifty Thrifty GenotypeGenotype’’))
��Ocean voyagesOcean voyages
•• Increased effect with Increased effect with
modernizationmodernization
��Island faminesIsland famines
(2) Fat and the Human Baby(2) Fat and the Human Baby’’s Brains Brain
(3) Fat for Reproduction(3) Fat for Reproduction
•• Reproduction is energetically Reproduction is energetically
expensive in femalesexpensive in females
Fat for ReproductionFat for Reproduction
•• Reproduction is energetically Reproduction is energetically
expensive in females expensive in females
•• Fat is laid down in women at Fat is laid down in women at
puberty and during pregnancypuberty and during pregnancy
Fat for ReproductionFat for Reproduction
•• Reproduction is Reproduction is energetically expensive in energetically expensive in females females
•• Fat is laid down in women Fat is laid down in women at puberty and during at puberty and during pregnancypregnancy
•• Fat is mobilized during Fat is mobilized during pregnancy, but particularly pregnancy, but particularly during lactation.during lactation.
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Body weight at parturition and duration of Body weight at parturition and duration of
postpartum amenorrhea in Bangladeshpostpartum amenorrhea in Bangladesh
0
2
4
6
8
10
12
14
16
18
Duration of Lactational
Amenorrhea (mo)
>44 kg 38-43.9 kg <38 kg
(Ford et al., 1989)
Fat for ReproductionFat for Reproduction
•• Fat is laid down in women at puberty and Fat is laid down in women at puberty and
during pregnancyduring pregnancy
•• Reproduction is energetically expensive Reproduction is energetically expensive
in femalesin females
•• Fat is mobilized during pregnancy, but Fat is mobilized during pregnancy, but
particularly during lactation.particularly during lactation.
•• Increased body weight correlated with Increased body weight correlated with
increased probability of conception, increased probability of conception,
shorter intershorter inter--birth intervals, higher birth intervals, higher
neonatal weight, etc.neonatal weight, etc.
Fat for ReproductionFat for Reproduction
•• Fat is laid down in women at puberty and Fat is laid down in women at puberty and during pregnancyduring pregnancy
•• Reproduction is energetically expensive Reproduction is energetically expensive in femalesin females
•• Fat is mobilized during pregnancy, but Fat is mobilized during pregnancy, but particularly during lactation.particularly during lactation.
•• Increased body weight related to Increased body weight related to increased probability of conception, increased probability of conception, shorter intershorter inter--birth intervals, higher birth intervals, higher neonatal weight, etc.neonatal weight, etc.
•• Easier for women to put on weight and Easier for women to put on weight and more difficult to losemore difficult to lose
Sexual DimorphismSexual Dimorphism
!Kung Sexual Dimorphism!Kung Sexual Dimorphism Obesity: Men vs. Women
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Human BreastsHuman Breasts
•• Humans are Humans are uniqueunique in in
having breast having breast
development development
unassociated with unassociated with
pregnancypregnancy
Human BreastsHuman Breasts
•• Humans are unique in Humans are unique in
having breast development having breast development
unassociated with unassociated with
pregnancypregnancy
•• Breasts are the earliest sign Breasts are the earliest sign
of puberty, approximately of puberty, approximately
two years before menarchetwo years before menarche
Human BreastsHuman Breasts
•• Humans are unique in Humans are unique in
having breast development having breast development
unassociated with unassociated with
pregnancypregnancy
•• Breasts are the earliest Breasts are the earliest
sign of puberty, sign of puberty,
approximately two approximately two
years before menarcheyears before menarche
•• Obtain full size before Obtain full size before
reach reproductive reach reproductive
maturitymaturity
Human BreastsHuman Breasts
•• Humans are unique in having Humans are unique in having
breast development breast development
unassociated with pregnancyunassociated with pregnancy
•• Breasts are the earliest sign Breasts are the earliest sign
of puberty, approximately of puberty, approximately
two years before menarchetwo years before menarche
•• Obtain full size before Obtain full size before
reach reproductive reach reproductive
maturitymaturity
•• Size not related to ability to Size not related to ability to
lactatelactate
•• Humans matedHumans mated dorsodorso--ventrally ventrally beforebefore bipedalismbipedalism. . Thus, onceThus, once bipedalism bipedalism evolved, needed a mimic of evolved, needed a mimic of buttocks to promote facebuttocks to promote face--toto--face intercourse (Morris, face intercourse (Morris, 1967)1967)
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(1) (1) Buttocks MimicryButtocks Mimicry
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•• Humans matedHumans mated dorsodorso--ventrally ventrally beforebefore bipedalismbipedalism. Thus, once. Thus, oncebipedalism bipedalism evolved, needed a evolved, needed a mimic of buttocks to promote mimic of buttocks to promote faceface--toto--face intercourse face intercourse (Morris, 1967)(Morris, 1967)
•• HOWEVERHOWEVER……
�� Fleshy buttocks didnFleshy buttocks didn’’t evolve t evolve untiluntil bipedalismbipedalism, thus couldn, thus couldn’’t t have been associated with have been associated with copulation beforecopulation before bipedalismbipedalism
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(1) (1) Buttocks MimicryButtocks Mimicry
•• Mimic of buttocks, promoting faceMimic of buttocks, promoting face--toto--face face intercourse afterintercourse after bipedalism bipedalism (Morris, 1967)(Morris, 1967)
•• HOWEVERHOWEVER……
��Fleshy buttocks didnFleshy buttocks didn’’t evolve t evolve untiluntil bipedalismbipedalism, , thus couldnthus couldn’’t have been associated with t have been associated with copulation beforecopulation before bipedalismbipedalism
��The sexual attractiveness of the breast may not The sexual attractiveness of the breast may not be a human universalbe a human universal
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(1) (1) Buttocks MimicryButtocks Mimicry
��Do males really need a Do males really need a ‘‘buttockbuttock--mimicmimic’’ to to promote arousal?promote arousal?
•• Infant flotation (Morgan, 1982)Infant flotation (Morgan, 1982)
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(2) (2) Infant FlotationInfant Flotation
•• Infant flotation (Morgan, Infant flotation (Morgan,
1982) 1982)
•• HOWEVERHOWEVER……
��We didnWe didn’’t evolve in the Water!t evolve in the Water!
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(2) Infant Flotation(2) Infant Flotation
•• Infant flotation (Morgan, Infant flotation (Morgan,
1982)1982)
•• HOWEVERHOWEVER……
��We didnWe didn’’t evolve in the watert evolve in the water
��Why are large breasts seen in Why are large breasts seen in
other apes after pregnancy other apes after pregnancy
then?then?
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(2) Infant Flotation(2) Infant Flotation
•• Infant flotation (Morgan, Infant flotation (Morgan,
1982)1982)
•• HOWEVERHOWEVER……
��We didnWe didn’’t evolve in the watert evolve in the water
��Why are large breasts seen in Why are large breasts seen in
other apes after pregnancy other apes after pregnancy
then?then?
��How would it work?How would it work?
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(2) Infant Flotation(2) Infant Flotation
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•• Breasts (and buttocks) as an indicator of Breasts (and buttocks) as an indicator of
nutritional status (Cant, 1981)nutritional status (Cant, 1981)
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(3) Indicator of Nutritional Status(3) Indicator of Nutritional Status
•• Breasts (and buttocks) as an indicator of Breasts (and buttocks) as an indicator of
nutritional status (Cant, 1981)nutritional status (Cant, 1981)
•• HOWEVERHOWEVER……
��Breast size isnBreast size isn’’t highly correlated with t highly correlated with
nutritional statusnutritional status
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(3) Indicator of Nutritional Status(3) Indicator of Nutritional Status
•• Breasts (and buttocks) as an indicator of Breasts (and buttocks) as an indicator of
nutritional status (Cant, 1981)nutritional status (Cant, 1981)
•• HOWEVERHOWEVER……
��Breast size isnBreast size isn’’t highly correlated with t highly correlated with
nutritional statusnutritional status
��No correlation between motherNo correlation between mother’’s fat levels and s fat levels and
milk quantitymilk quantity
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(3) Indicator of Nutritional Status(3) Indicator of Nutritional Status
•• Breasts (and buttocks) as an indicator of Breasts (and buttocks) as an indicator of
nutritional status (Cant, 1981)nutritional status (Cant, 1981)
•• HOWEVERHOWEVER……
��Breast size isnBreast size isn’’t highly correlated with t highly correlated with
nutritional statusnutritional status
��No correlation between fat levels and milk No correlation between fat levels and milk
quantityquantity
��Breasts comprised of only 4% adipose tissue in Breasts comprised of only 4% adipose tissue in
young womenyoung women
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(3) Indicator of Nutritional Status(3) Indicator of Nutritional Status
•• Breasts (and buttocks) as an indicator of nutritional Breasts (and buttocks) as an indicator of nutritional
status (Cant, 1981)status (Cant, 1981)
•• HOWEVERHOWEVER……
��Breast size isnBreast size isn’’t highly correlated with nutritional statust highly correlated with nutritional status
��No correlation between fat levels and milk quantityNo correlation between fat levels and milk quantity
��Breasts composed of only 4% adipose tissue in young Breasts composed of only 4% adipose tissue in young
womenwomen
��Fat mostly mobilized from stores in groin (femoral) Fat mostly mobilized from stores in groin (femoral)
rather than in breast during lactation (rather than in breast during lactation (Rebuffe ScriveRebuffe Scrive, ,
1987)1987)
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(3) Indicator of Nutritional Status(3) Indicator of Nutritional Status
•• Breasts as an indicator of ovulatory status Breasts as an indicator of ovulatory status
(Gallup, 1982)(Gallup, 1982)
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(4) Indicator of Ovulatory Status(4) Indicator of Ovulatory Status
88
•• Breasts as an indicator of ovulatory Breasts as an indicator of ovulatory
potential (Gallup, 1982)potential (Gallup, 1982)
•• HOWEVERHOWEVER……
��Breasts develop before ovulation beginsBreasts develop before ovulation begins
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(4) Indicator of (4) Indicator of Ovulatory Ovulatory StatusStatus
•• Breasts as an indicator of ovulatory Breasts as an indicator of ovulatory
potential (Gallup, 1982)potential (Gallup, 1982)
•• HOWEVERHOWEVER……
��Breasts develop before ovulation beginsBreasts develop before ovulation begins
��Breast size is largest when NOT ovulating (i.e. Breast size is largest when NOT ovulating (i.e.
when pregnant)when pregnant)
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(4) Indicator of (4) Indicator of Ovulatory Ovulatory StatusStatus
•• Signal of evolution of permanent estrus Signal of evolution of permanent estrus
((Szalay Szalay and Costello, 1991): A sign of and Costello, 1991): A sign of
sexual availability instead of estrussexual availability instead of estrus
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(5) Indicator of Sexual Availability(5) Indicator of Sexual Availability
•• Signal of evolution of Signal of evolution of
permanent estrus (permanent estrus (Szalay Szalay
and Costello, 1991): A sign and Costello, 1991): A sign
of sexual availability instead of sexual availability instead
of estrusof estrus
•• HOWEVERHOWEVER……
��Breasts donBreasts don’’t indicate sexual t indicate sexual
availability in other primates.availability in other primates.
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(5) Indicator of Sexual Availability(5) Indicator of Sexual Availability
•• Signal of evolution of permanent Signal of evolution of permanent
estrus (estrus (Szalay Szalay and Costello, 1991). and Costello, 1991).
A sign of sexual availability instead A sign of sexual availability instead
of estrusof estrus
•• HOWEVERHOWEVER……
��Breasts donBreasts don’’t indicate sexual t indicate sexual
availability in other primates.availability in other primates.
��Other primates (orangutans) that Other primates (orangutans) that
have permanent estrus, donhave permanent estrus, don’’t t
have early breast developmenthave early breast development
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(5) Indicator of Sexual Availability(5) Indicator of Sexual Availability
•• Enlarged breasts Enlarged breasts evolved in hominid evolved in hominid females as an honest females as an honest signal of age and, thus, signal of age and, thus, residual reproductive residual reproductive valuevalue
(Marlowe, 1998)
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(6) The (6) The Nubility Nubility HypothesisHypothesis
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Reproductive ValueReproductive Value
•• Enlarged breasts evolved in hominid Enlarged breasts evolved in hominid females as an honest signal of age and, thus, females as an honest signal of age and, thus, residual reproductive valueresidual reproductive value
•• Large breasts are more prone to sagging Large breasts are more prone to sagging with age with age —— thus preferred by males because thus preferred by males because they are an honest signal of agethey are an honest signal of age
(Marlowe, 1998)
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(6) The (6) The Nubility Nubility HypothesisHypothesis
Breasts (inBreasts (in HadzaHadza) stay firm through the years of ) stay firm through the years of
peak fertility, even after 2peak fertility, even after 2--3 children.3 children.
––HOWEVERHOWEVER……
�� If unchanged .. DoesnIf unchanged .. Doesn’’t this contradict t this contradict that theythat they’’re a signal of age?re a signal of age?
•• Enlarged breasts evolved in hominid Enlarged breasts evolved in hominid
females as an honest signal of age and, thus, females as an honest signal of age and, thus,
residual reproductive value residual reproductive value
•• Large breasts are more prone to sagging Large breasts are more prone to sagging
with age with age —— thus preferred by males because thus preferred by males because
they are an honest signal of agethey are an honest signal of age
•• HOWEVERHOWEVER……
��Are large breasts preferred crossAre large breasts preferred cross--culturally?culturally?
��Are breasts considered sexual crossAre breasts considered sexual cross--culturally?culturally?
(Marlowe, 1998)
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(6) The (6) The Nubility Nubility HypothesisHypothesis
•• Breast development is the 1st sign of Breast development is the 1st sign of puberty ~ two years before menarchepuberty ~ two years before menarche
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(7) Breasts as a Signal of Reproductive Maturity(7) Breasts as a Signal of Reproductive Maturity
(Knott)
•• Breast development is the 1st Breast development is the 1st sign of puberty ~ two years sign of puberty ~ two years before menarchebefore menarche
•• Importance of female Importance of female reproductive value in human reproductive value in human mate choicemate choice–– Females usually chosenFemales usually chosen at peak at peak
reproductive valuereproductive value
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(7) (7) Breasts as a Signal of Reproductive MaturityBreasts as a Signal of Reproductive Maturity
(Knott)
•• Breast development is the 1st sign of Breast development is the 1st sign of puberty ~ two years before menarchepuberty ~ two years before menarche
•• Importance of female reproductive Importance of female reproductive value in human mate choicevalue in human mate choice–– Mates usually chosenMates usually chosen at peak at peak
reproductive valuereproductive value
•• Breast adipose tissue has no relation to Breast adipose tissue has no relation to milk productionmilk production
Explanations for Features of Human Breasts:Explanations for Features of Human Breasts:
(7) (7) Breasts as a Signal of Reproductive MaturityBreasts as a Signal of Reproductive Maturity
(Knott)
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Human BreastsHuman Breasts
•• All humans have breast All humans have breast
development at puberty, development at puberty,
before pregnancybefore pregnancy
•• Universal human signal Universal human signal of sexual maturityof sexual maturity
•• Unclear if universally Unclear if universally regarded as regarded as ““sexual,sexual,””but still may serve a but still may serve a signaling functionsignaling function
Female BodiesFemale Bodies
Corsets: Decreasing Waist to Corsets: Decreasing Waist to
Hip Ratio (WHR)Hip Ratio (WHR)
“Satin jacquard corset. Romantic
and timeless, the ultimate in
hourglass shaping. Flowers bloom
on satin finished in delicate lace
trim. Flexible boning and a lace-up
back cinch the waist.”
Studies Studies
of Waist of Waist
to Hip to Hip
RatioRatio
(Singh, 1993, 1994)
Waist to Hip Ratio (Waist to Hip Ratio (WHRWHR))
1.1. Measure the smallest part of your Measure the smallest part of your waist with a tape measure.waist with a tape measure.
2.2. Measure the biggest part of your Measure the biggest part of your hips (the part where your buttocks hips (the part where your buttocks stick out the most) with a tape stick out the most) with a tape measure.measure.
3.3. Divide the waist measurement by Divide the waist measurement by your hip measurement. your hip measurement.
Males use WHR to assess females Males use WHR to assess females
because:because:
•• Females have lower WHR than malesFemales have lower WHR than males
•• NonNon--pregnant women have a lower WHRpregnant women have a lower WHR
•• Lower WHR = fewer health problemsLower WHR = fewer health problems
(Singh, 1993, 1994)
1111
Studies of Waist to Hip Studies of Waist to Hip
RatioRatio
(Singh, 1993, 1994)
•• Which figure do you find most Which figure do you find most
attractive?attractive?
•• Which figure would you Which figure would you
choose for a long term mate?choose for a long term mate?
•• Which figure is healthiest?Which figure is healthiest?
Sculpture and WHR CrossCross--CulturalCultural
StudiesStudies
•• Hadza Hadza of Tanzaniaof Tanzania
(Marlowe & Wetsman, 2000)
US Men
.4 .5 .6 .7 .8 .9 1.0
(Marlowe & Wetsman, 2000)
Attractiveness AssessmentAttractiveness Assessment
2.5
3
3.5
4
4.5
5
5.5
.4 .5 .6 .7 .8 .9 1(Marlowe & Wetsman, 2000)
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Health AssessmentHealth Assessment
2
2.5
3
3.5
4
4.5
5
5.5
.4 .5 .6 .7 .8 .9 1(Marlowe & Wetsman, 2000)
Preference for a WifePreference for a Wife
2.5
3
3.5
4
4.5
5
5.5
.4 .5 .6 .7 .8 .9 1(Marlowe &
Wetsman, 2000)
However, another issue:
Attractiveness of the
buttocks
The studies that have assessed men’s
preferences for WHR have used pictures of
women viewed from the front.
Frontal pictures show the waist and hips but
NOT the buttocks.
Some termsSome terms……
Actual WHR = as measured with a tape measure
Frontal WHR= measurement of waist and hip in 2 dimensional form
Profile WHR = measurement of waist & buttocks in 2
dimensional form
1313
To get a fuller picture, we need to know
men’s preferences for profile WHR
1. Test for profile WHR
preferences in American and
Hadza men
2. Investigate whether men’s
preferences track the population mean
for actual WHR of women.
Methods: stimuliMethods: stimuli
.55 .60 .65 .70 .75 .65 .70 .75.60.55
The five drawings were placed in a horizontal row in random order in front of the subject, who was then asked to choose the female they found most attractive. After they chose, the card was removed, and the subject asked to choose the most attractive among the four that remained.
This process was repeated until all five cards were ranked.
SubjectsSubjects
American men:American men: 1818--72 yrs 72 yrs
(M=29, S.D.=13.52, n=108)(M=29, S.D.=13.52, n=108)
Hadza men:Hadza men: 1515--75 yrs 75 yrs
(M=35, S.D.=14.23, n=110)(M=35, S.D.=14.23, n=110)
The percentage of subjects who chose a given profile WHR as their first choice. Solid line indicates Hadza men (n =47), and dotted line indicates American men (n =94).
Solid Line = Hadza
Dotted = US men
The most common
1st choice on all 3
criteria:
Hadza: .60
US Men: .65
What is the What is the ““actualactual”” preferred preferred WHR for both Hadza and US men? WHR for both Hadza and US men?
US Men: US Men: US Men: US Men: preferred frontal WHR = .70 preferred frontal WHR = .70 preferred frontal WHR = .70 preferred frontal WHR = .70 (Marlowe & (Marlowe & (Marlowe & (Marlowe &
WestmanWestmanWestmanWestman, 2001), 2001), 2001), 2001)
preferred profile WHR = .65preferred profile WHR = .65preferred profile WHR = .65preferred profile WHR = .65
Hadza Men:Hadza Men:Hadza Men:Hadza Men:preferred frontal WHR = .90 preferred frontal WHR = .90 preferred frontal WHR = .90 preferred frontal WHR = .90 (Marlowe & (Marlowe & (Marlowe & (Marlowe &
WestmanWestmanWestmanWestman, 2001), 2001), 2001), 2001)
preferred profile WHR = .60preferred profile WHR = .60preferred profile WHR = .60preferred profile WHR = .60
Profile: Hadza prefer lower
ratio = larger
buttocks
Frontal:
Hadza prefer
higher ratio = larger waist
Calculated Theoretical Preference for Calculated Theoretical Preference for Calculated Theoretical Preference for Calculated Theoretical Preference for Actual WHR for U.S. & Hadza MenActual WHR for U.S. & Hadza MenActual WHR for U.S. & Hadza MenActual WHR for U.S. & Hadza Men
= .68 = .68 = .68 = .68
= .78 = .78 = .78 = .78
Their theoretical
preferences may not
be as different as previously thought…
however, they still
differ considerably.
1414
Do menDo men’’s preferences for actual WHR track the s preferences for actual WHR track the
population mean WHR?population mean WHR?
1. We measured actual WHR of Hadza women to compare to Ameri1. We measured actual WHR of Hadza women to compare to American Women: can Women:
Hadza women 17- 81n = 53Mean (WHR) = .83
Range (WHR) = 0.69 - 0.94
S.D. (WHR) = .05
Mean (age) = 37.5
S.D. (age) = 16.1)
Hadza women 17-24 yearsn = 10
Mean (WHR) = .79
Hadza Female WHR (n = 75)
Do menDo menDo menDo menDo menDo menDo menDo men’’’’’’’’s preferences for actual WHR s preferences for actual WHR s preferences for actual WHR s preferences for actual WHR s preferences for actual WHR s preferences for actual WHR s preferences for actual WHR s preferences for actual WHR track the population mean WHR?track the population mean WHR?track the population mean WHR?track the population mean WHR?track the population mean WHR?track the population mean WHR?track the population mean WHR?track the population mean WHR?
2. We compared Hadza women mean WHR to American women mean W2. We compared Hadza women mean WHR to American women mean W2. We compared Hadza women mean WHR to American women mean W2. We compared Hadza women mean WHR to American women mean W2. We compared Hadza women mean WHR to American women mean W2. We compared Hadza women mean WHR to American women mean W2. We compared Hadza women mean WHR to American women mean W2. We compared Hadza women mean WHR to American women mean WHRHRHRHRHRHRHRHR
Chapman (2004)Chapman (2004)0.730.73 ++ .04 (.65.04 (.65––.83).83)19.6 19.6 ++ 1.1 (181.1 (18––23)23)Young American Young American
Students (n = 68)Students (n = 68)
0.830.83 ++ .06 (.69.06 (.69––.94).94)37.5 37.5 ++ 16.1 (1716.1 (17––82)82)Hadza (n =53)Hadza (n =53)
0.790.79 ++ .04 (.72.04 (.72––.87).87)22 22 ++ 2.23 (172.23 (17––24)24)Hadza (n =10)Hadza (n =10)
Thornhill Thornhill & & Grammer Grammer
(1999)(1999)
0.720.72 ++ .04.0423 (1823 (18––30)30)Americans recruited for Americans recruited for
study with nude photo study with nude photo
taken (n = 92)taken (n = 92)
Hughes Gallup & Hughes Gallup &
Gordon (2003)Gordon (2003)
0.770.77 ++ .049 (.69.049 (.69––.87).87)19.6 (1819.6 (18––44)44)American Students American Students
(n = 55) (n = 55)
Singh & Singh & ZambaranoZambarano
(1997)(1997)
0.740.74 ++ .08 (.59.08 (.59––.95).95)31.7 31.7 ++ 6.4 (236.4 (23––50)50)American NursesAmerican Nurses
(n = 69)(n = 69)
ReferenceReferenceWHRWHRAgeAgeSampleSample
MenMen’’s preferences MAY map onto s preferences MAY map onto
geographic variation in the shape of geographic variation in the shape of
females, some females having a wider females, some females having a wider
pelvis and hips, and others narrower pelvis and hips, and others narrower
hips but perhaps more protruding hips but perhaps more protruding
buttocks. buttocks.
Also since WHR reaches a low soon Also since WHR reaches a low soon
after menarche, male preference for a after menarche, male preference for a
low WHR might be an age preference low WHR might be an age preference
for for nubility nubility and max. reproductive and max. reproductive
valuevalue-- Hadza prefer actual WHR of .78 Hadza prefer actual WHR of .78
and the WHR of 17and the WHR of 17--24 yr Hadza 24 yr Hadza
women is .79. women is .79.
Some wild speculations in order of Some wild speculations in order of
wildnesswildness……•• Some Hadza women may have been pregnant Some Hadza women may have been pregnant ……
•• WHR rises with parityWHR rises with parity-- perhaps Hadza WHR is higher because perhaps Hadza WHR is higher because Hadza women give birth to more children than American Hadza women give birth to more children than American women. women. (TFR for Hadza is 6.2 births per lifetime compared to 2.1 in Ame(TFR for Hadza is 6.2 births per lifetime compared to 2.1 in American rican women).women).
•• Larger gut needed to hold the amount of bulky, fibrous tubers.Larger gut needed to hold the amount of bulky, fibrous tubers.
•• Hadza women may need to be more physically active, which Hadza women may need to be more physically active, which might favor higher androgen levels that could result in more fatmight favor higher androgen levels that could result in more fatbeing deposited in the abdominal area.being deposited in the abdominal area.
•• Women who walk more may have a more maleWomen who walk more may have a more male--like pelvis like pelvis trading off optimality in parturition for more efficient trading off optimality in parturition for more efficient locomotion.locomotion.
WHR, Breast Size andWHR, Breast Size and EstradiolEstradiol
10
12
14
16
18
20
22
24
26
Salivary Estradiol (pmol/l)
Narrow waist,
large breasts
Narrow waist,
small breasts
Broad waist,
large breasts
Broad waist,
small breasts
Jasienska et al. , 2004
1515
WHR, Breast Size and WHR, Breast Size and EstradiolEstradiol
0
5
10
15
20
25
30
Salivary Estradiol (pmol/l)
Narrow waist,
large breasts
Narrow waist,
small breasts
Broad waist,
large breasts
Broad waist,
small breastsJasienska et al. , 2004
•• Women with narrow waists and large breasts had 37% Women with narrow waists and large breasts had 37%
higher mean midhigher mean mid--cyclecycle estradiol estradiol than other categoriesthan other categories
–– This level of difference in This level of difference in estradiol estradiol associated with 3x greater associated with 3x greater
probability of conception from Lipson & Ellison 1996 study.probability of conception from Lipson & Ellison 1996 study.
•• Women with larger breasts had higherWomen with larger breasts had higher estradiol estradiol
independent of WHRindependent of WHR
•• Women with low WHR had higherWomen with low WHR had higher estradiol estradiol and and
progesterone than women with high WHR.progesterone than women with high WHR.
Female Beauty CrossFemale Beauty Cross--CulturallyCulturally
•• More subsistenceMore subsistence--oriented a society and the oriented a society and the
more energetically expensive womenmore energetically expensive women’’s s
work work —— the more men will find the more men will find ‘‘fatterfatter’’
women attractive.women attractive.
Female Beauty CrossFemale Beauty Cross--CulturallyCulturally
•• 81% of cultures in the HRAF(ethnographic 81% of cultures in the HRAF(ethnographic
records) preferred plumpness as a female records) preferred plumpness as a female
body characteristicbody characteristic
Venus of Venus of Wallendorf Wallendorf ~ 25,000 y.a.~ 25,000 y.a.
Bathers - 1888
1616
1717
Boobs are Back!Boobs are Back!
Why has the Why has the ““idealideal”” female body female body
image changed in the West?image changed in the West?
Why has the Why has the ““idealideal”” female body female body
image changed in the West?image changed in the West?
•• Being thin associated with being higher Being thin associated with being higher
status, control of eating in a food abundant status, control of eating in a food abundant
societysociety
Why has the Why has the ““idealideal”” female body female body
image changed in the West?image changed in the West?
•• Being thin associated with being higher Being thin associated with being higher
status, control of eating in a food abundant status, control of eating in a food abundant
societysociety
•• Preference of fashion designers?Preference of fashion designers?
The Ideal Female Body and the The Ideal Female Body and the
Workforce ImageWorkforce Image
•• Changing role of women Changing role of women ——entry into the professional entry into the professional ““malemale”” workforceworkforce
•• Women often judged Women often judged
professionally according to professionally according to
body imagebody image
•• Women with more Women with more ‘‘femalefemale’’
bodies considered less bodies considered less
competent.competent.
1818
The Ideal Female Body and the The Ideal Female Body and the
Workforce ImageWorkforce Image
•• More More ““femalefemale”” looking women (more curvaceous, looking women (more curvaceous, bigger breasts) viewed as being less professional, bigger breasts) viewed as being less professional, less intelligent (less intelligent (Kleinke Kleinke && Staneski Staneski 1980)1980)
•• Personnel consultants: more feminine the grooming Personnel consultants: more feminine the grooming
-- less likely to judge the woman as a potential less likely to judge the woman as a potential
manager, interested in work, independent.manager, interested in work, independent.
Changes in Bust:Hip RatiosChanges in Bust:Hip Ratios
•• Question: If curvaceous/bigger breasted Question: If curvaceous/bigger breasted
women are perceived as less competent and women are perceived as less competent and
intelligent, then did the standard of bodily intelligent, then did the standard of bodily
attractiveness for women become less attractiveness for women become less
curvaceous/bigger breasted during periods curvaceous/bigger breasted during periods
when competence and intelligence was most when competence and intelligence was most
highly valued?highly valued?
(Silverstein, 1986)
Changes in Bust:Hip RatiosChanges in Bust:Hip Ratios
Silverstein et al., 1986
Peak in female professionals
Peak in female college graduates
Eating DisordersEating Disorders
Body Image & DietingBody Image & Dieting
•• 64% of women but only 23% of men who had 64% of women but only 23% of men who had
never been overweight reported a history of never been overweight reported a history of
dieting to lose weight (Jeffrey et al. 1984)dieting to lose weight (Jeffrey et al. 1984)
Body Image & DietingBody Image & Dieting
•• In SilversteinIn Silverstein’’s study the proportion of articles s study the proportion of articles
dealing with obesity peaked the following dealing with obesity peaked the following
year after each of the low points (1925) and year after each of the low points (1925) and
(1970(1970’’s).s).
1919
Body Image & DietingBody Image & Dieting
•• 64% of women but only 23% of men who had never 64% of women but only 23% of men who had never
been overweight reported a history of dieting to lose been overweight reported a history of dieting to lose
weight (Jeffrey et al. 1984)weight (Jeffrey et al. 1984)
•• In SilversteinIn Silverstein’’s study the proportion of articles s study the proportion of articles
dealing with obesity peaked the following year after dealing with obesity peaked the following year after
each of the low points (1925) and (1970each of the low points (1925) and (1970’’s). s).
•• When standard of female When standard of female ““curvaceousnesscurvaceousness”” reached reached
itit’’s lowest point, so did the proportion of very thin s lowest point, so did the proportion of very thin
college women.college women.
Body Image & Dieting in Body Image & Dieting in ‘‘NormalNormal’’ WomenWomen
•• A large majority of women report feeling fat, despite being A large majority of women report feeling fat, despite being
normal weightnormal weight
•• One survey One survey -- 75% of female respondents felt 75% of female respondents felt ‘‘too fattoo fat’’
•• Studies of nonStudies of non--eating disordered patients reveal that many eating disordered patients reveal that many
psychological traits thought to be representative of patients psychological traits thought to be representative of patients
with eating disorders are broadly spread across all womenwith eating disorders are broadly spread across all women
•• Garner: Women who were weight preoccupied similar to Garner: Women who were weight preoccupied similar to
anorexics in terms of degree of body dissatisfaction.anorexics in terms of degree of body dissatisfaction.
Eating DisordersEating Disorders
•• ““Anorexia and bulimia strike one million Anorexia and bulimia strike one million
American women every year (Wolf, 1991)American women every year (Wolf, 1991)””
•• Up to 19% of anorexic women die of their Up to 19% of anorexic women die of their
affliction (Hsu, 1980)affliction (Hsu, 1980)””
Who suffers from Eating Disorders?Who suffers from Eating Disorders?
•• 9595--99% of clinical cases of eating disorders 99% of clinical cases of eating disorders
occur in women, particularly upper middle occur in women, particularly upper middle
class white womenclass white women
•• Particularly prevalent in women who stress Particularly prevalent in women who stress academic achievements and professional academic achievements and professional careerscareers
��““In one college population, 78% of women had In one college population, 78% of women had engaged in binge eating (Hawkins & Clement, engaged in binge eating (Hawkins & Clement, 1980)1980)””
��On college campuses one in five women may On college campuses one in five women may suffer from anorexia (suffer from anorexia (BrumbergBrumberg, 1988), 1988)
Is it CrossIs it Cross--Cultural?Cultural?
•• Where observed, occurs in women of high Where observed, occurs in women of high
statusstatus
•• Malaysia: quite low, but where observed Malaysia: quite low, but where observed 67% among Chinese subpopulation which 67% among Chinese subpopulation which are:are:
–– Most EducatedMost Educated
–– WealthiestWealthiest
–– Highest # ofHighest # of professional womenprofessional women
Body Perceptions
(Thompson)
2020
Why are eating disorders Why are eating disorders
predominantly found in women?predominantly found in women?
•• Psychological studies indicate that eating Psychological studies indicate that eating
disorders have emerged because women disorders have emerged because women
seek approval through their body image seek approval through their body image
((BardwickBardwick, 1971), 1971)
But, these studies do not address But, these studies do not address WHYWHY female female
bodies should be such a focal point of bodies should be such a focal point of
attentionattention
Body Image and Eating Disorders:Body Image and Eating Disorders:
An Evolutionary HypothesisAn Evolutionary Hypothesis
•• Women in all societies have larger Women in all societies have larger
subcutaneous fat deposits than do mensubcutaneous fat deposits than do men
(Knott)
Body Image and Eating Disorders:Body Image and Eating Disorders:
An Evolutionary HypothesisAn Evolutionary Hypothesis
•• Women in all societies have larger Women in all societies have larger
subcutaneous fat deposits than do mensubcutaneous fat deposits than do men
•• Reproduction is limited by energy Reproduction is limited by energy
availability in womenavailability in women
(Knott)
Body Image and Eating Disorders:Body Image and Eating Disorders:
An Evolutionary HypothesisAn Evolutionary Hypothesis
•• Women in all societies have larger Women in all societies have larger
subcutaneous fat deposits than do mensubcutaneous fat deposits than do men
•• Reproduction is limited by energy Reproduction is limited by energy
availability in womenavailability in women
•• Women have been selected over Women have been selected over
evolutionary time to put on fat depositsevolutionary time to put on fat deposits
(Knott)
How does this effect female How does this effect female
psychology?psychology?
•• During the EEA there may have been a During the EEA there may have been a
selective advantage to maximizing food selective advantage to maximizing food
intake when possibleintake when possible
(Knott)
Fat and Female AdaptationFat and Female Adaptation
•• Thus, women have physiological and Thus, women have physiological and
possibly psychological adaptations to possibly psychological adaptations to
enable them to store excess food as fatenable them to store excess food as fat
(Knott)
2121
Female Body ImageFemale Body Image
•• Female bodies are Female bodies are
evaluated in most (all?) evaluated in most (all?)
societiessocieties
(Knott)
Female Body ImageFemale Body Image
•• Female bodies are evaluated Female bodies are evaluated
in most (all?) societiesin most (all?) societies
•• Up until the 20th century in Up until the 20th century in
the west, and still in other the west, and still in other
human societies, men prefer human societies, men prefer
women who are above women who are above
average in body weight:average in body weight:
(Knott)
Female Body ImageFemale Body Image
•• Female bodies are evaluated in most (all?) Female bodies are evaluated in most (all?)
societiessocieties
•• Up until the 20th century in the west, and still Up until the 20th century in the west, and still
in other human societies, men prefer women in other human societies, men prefer women
who are above average in body weight:who are above average in body weight:
•• Fat in women was/is viewed as denoting:Fat in women was/is viewed as denoting:
–– HealthHealth
–– Reproductive abilityReproductive ability
–– Associated with higher status (more access to Associated with higher status (more access to
resources)resources)(Knott)
The ConsequenceThe Consequence
•• Thus, throughout evolutionary Thus, throughout evolutionary
history women have been history women have been
selected to maximize food selected to maximize food
intake and store fat reserves.intake and store fat reserves.
(Knott)
The ConsequenceThe Consequence
•• Thus, throughout evolutionary Thus, throughout evolutionary
history women have been selected history women have been selected
to maximize food intake and store to maximize food intake and store
fat reserves.fat reserves.
•• This has been in This has been in
accordance with the accordance with the
desired female bodydesired female body
(Knott)
The ConsequenceThe Consequence
•• Thus, throughout evolutionary history Thus, throughout evolutionary history women have been selected to maximize food women have been selected to maximize food intake and store fat reserves.intake and store fat reserves.
•• This has been in accordance with the desired This has been in accordance with the desired female bodyfemale body
•• But, with overabundance of food But, with overabundance of food in our society and changing in our society and changing standards of ideal female body standards of ideal female body image, these no longer go image, these no longer go togethertogether
(Knott)
2222
The ConsequenceThe Consequence
•• Thus, throughout evolutionary history Thus, throughout evolutionary history women have been selected to maximize women have been selected to maximize food intake and store fat reserves.food intake and store fat reserves.
•• This has been in accordance with the This has been in accordance with the desired female bodydesired female body
•• But, with overabundance of food in our But, with overabundance of food in our society and changing standards of ideal society and changing standards of ideal female body image, these no longer go female body image, these no longer go togethertogether
•• However, female physiology However, female physiology and psychology have NOT and psychology have NOT changed. Still adapted to changed. Still adapted to maximize calories.maximize calories.
(Knott)
The ConsequenceThe Consequence
•• Thus, our physiological and Thus, our physiological and
psychological adaptations to psychological adaptations to
put on fat reserves are now put on fat reserves are now
in conflict with the current in conflict with the current
““idealideal”” body imagebody image
(Knott)
The ConsequenceThe Consequence•• Thus, our physiological and psychological Thus, our physiological and psychological
adaptations to put on fat reserves are now in adaptations to put on fat reserves are now in
conflict with the current conflict with the current ““idealideal”” body imagebody image
•• This causes psychological problems This causes psychological problems
and behaviors such as and behaviors such as
–– Fixation on food, but not eatingFixation on food, but not eating
––Binging and then purgingBinging and then purging
(Knott)
The ConsequenceThe Consequence•• Thus, throughout evolutionary history women have been Thus, throughout evolutionary history women have been
selected to maximize food intake and store fat reserves.selected to maximize food intake and store fat reserves.
•• This has been in accordance with the desired female This has been in accordance with the desired female bodybody
•• But, with overabundance of food in our society and But, with overabundance of food in our society and changing standards of ideal female body image, these no changing standards of ideal female body image, these no longer go togetherlonger go together
•• But, female physiology and psychology has not But, female physiology and psychology has not changed. Still adapted to maximize calories. changed. Still adapted to maximize calories.
•• Thus, our physiological and psychological adaptations to Thus, our physiological and psychological adaptations to put on fat reserves are now in conflict with the current put on fat reserves are now in conflict with the current ““idealideal”” body imagebody image
•• This causes psychological problems and behaviors such This causes psychological problems and behaviors such as as
–– Fixation on food, but not eatingFixation on food, but not eating
–– Binging and then purgingBinging and then purging (Knott)
Next Time...Next Time...•• Control of Female FertilityControl of Female Fertility
–– AbortionAbortion
–– InfanticideInfanticide
–– NeglectNeglect
•• Film: ChinaFilm: China’’s Only Childs Only Child
Next Time...Next Time...
•• Subsistence TransitionsSubsistence Transitions
–– Hunting & GatheringHunting & Gathering
–– HorticultureHorticulture
–– AgricultureAgriculture
•• IndustrializationIndustrialization
•• The Demographic TransitionThe Demographic Transition
•• Population GrowthPopulation Growth
•• Limiting fertilityLimiting fertility
•• PostPost--IndustrialismIndustrialism
Subsistence Transitions, Subsistence Transitions,
WomenWomen’’s Status and Biologys Status and Biology