lecture 20: fatness & the fat: where is it...

11

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


•• 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.


•• 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


•• 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

22


•• 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)

33

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


•• 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.

44

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 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 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

55

Human BreastsHuman Breasts

•• Humans are Humans are uniqueunique in in

having breast having breast

development development

unassociated with unassociated with

pregnancypregnancy


•• Humans are unique in Humans are unique in

having breast development having breast development


pregnancypregnancy

•• Breasts are the earliest sign Breasts are the earliest sign

of puberty, approximately of puberty, approximately

two years before menarchetwo years before menarche


•• Humans are unique in Humans are unique in

having breast development having breast development


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


•• 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

66

•• 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



•• Mimic of buttocks, promoting faceMimic of buttocks, promoting face--toto--face face intercourse afterintercourse after bipedalism bipedalism (Morris, 1967)(Morris, 1967)


��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



��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)


(2) (2) Infant FlotationInfant Flotation

•• Infant flotation (Morgan, Infant flotation (Morgan,

1982) 1982)


��We didnWe didn’’t evolve in the Water!t evolve in the Water!


(2) Infant Flotation(2) Infant Flotation


1982)1982)


��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?




1982)1982)


��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?



77

•• Breasts (and buttocks) as an indicator of Breasts (and buttocks) as an indicator of

nutritional status (Cant, 1981)nutritional status (Cant, 1981)


(3) Indicator of Nutritional Status(3) Indicator of Nutritional Status




��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








��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



•• Breasts (and buttocks) as an indicator of nutritional Breasts (and buttocks) as an indicator of nutritional

status (Cant, 1981)status (Cant, 1981)


��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)



•• Breasts as an indicator of ovulatory status Breasts as an indicator of ovulatory status

(Gallup, 1982)(Gallup, 1982)


(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)


��Breasts develop before ovulation beginsBreasts develop before ovulation begins


(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)


��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)


(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


(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


��Breasts donBreasts don’’t indicate sexual t indicate sexual

availability in other primates.availability in other primates.



•• 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


��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



•• 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)


(6) The (6) The Nubility Nubility HypothesisHypothesis

99

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)



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


��Are large breasts preferred crossAre large breasts preferred cross--culturally?culturally?

��Are breasts considered sexual crossAre breasts considered sexual cross--culturally?culturally?

(Marlowe, 1998)



•• Breast development is the 1st sign of Breast development is the 1st sign of puberty ~ two years before menarchepuberty ~ two years before menarche


(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


(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


(7) (7) Breasts as a Signal of Reproductive MaturityBreasts as a Signal of Reproductive Maturity

(Knott)

1010


•• 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)

1212

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

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?



•• 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



•• 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)


•• 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


•• 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)





•• Reproduction is limited by energy Reproduction is limited by energy

availability in womenavailability in women

(Knott)





•• 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 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 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)


•• 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)


•• 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


•• 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)


•• 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

lecture 20: fatness & the fat: where is it...

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