Human Variation Sexual Dimorphism 1

KIN-Scale Proportionality Profile KIN-Scale data composed of data from Kin 303 students Means and SEMs of z-values for KIN-Scale Males (n=230) and Females (n=336) Visual test of significance allows for a lot of information to be portrayed in one figure

Sexual Dimorphism in KIN-Scale subjects No difference in proportional weight Male-Female difference greatest in: Triceps, Biceps, Front Thigh and Medial Calf Skinfolds Secondary sexual adiposity

Sexual Dimorphism in KIN-Scale subjects

Representative Measures  Muscle Mass  Muscle X-sectional Area  Skinfold-Adjusted Arm Girth – Muscularity Indicator G Ga = G - (3.14xS) S = Skinfold Thickness G = Girth Ga = Skinfold adjusted Girth Ga S G

Girth adjusted for Skinfold at that site GirthSkinfold s.a. Arm girthRelaxed Arm GirthTriceps s.a. Chest girthChestSubscapular s.a. Thigh girthThighFront Thigh s.a. Calf girthCalfMedial Calf s.a. Forearm girthMaximum ForearmForearm s.a. Girth (cm) = Girth (cm) - (Π x Skinfold (mm) / 10)

Sexual Dimorphism in KIN-Scale subjects s.a. Girths are Muscularity indicators Greatest differences between the sexes in the upper body Greatest potential for hypertrophy in the upper body Muscularity profile is very sensitive to the specific activity of the individual

Sexual Dimorphism in KIN-Scale subjects Proportionally larger sitting height in females Males tend to have proportionally longer limbs. Biggest difference in distal segments

Sexual Dimorphism in KIN-Scale subjects Humerus to Femur Width differences reflects muscularity differences Males have broader and deeper chests proportionally. Classic hip-shoulder dimorphism: Males proportionally wider shoulders Females have proportionally wider hips

Shoulder-Hip Dimorphism 10 SexNMean Std. Deviation Biacromial/Biiliocristal BreadthMale Female

11 2D:4D Ratio (2 nd digit length to 4 th digit length ratio) SexNMeanStd. Deviation Male Female D 4D a Allison A. Bailey, Peter L. Hurda, Department of Psychology, University of Alberta. 2004

2D:4D Ratio  Ratio determined in utero  2D:4D is negatively correlated with prenatal testosterone and positively correlated with prenatal estrogen  Larger ratio in females  Married women had higher 2D:4D ratios than unmarried women  Significant negative associations were found between 2D:4D in men and reproductive success and significant positive relationships between 2D:4D in women and reproductive success  Found to be related to:  Aggression  Competitive success  Sexual orientation

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Ethnicity and Race  Ethnic group  a socially defined category of people who identify with each other based on common ancestral, social, cultural or national experience.  Race  a group of people identified as distinct from other groups because of supposed physical or genetic traits shared by the group. 14

15 Racial/Ethnic and Individual Differences Chinese South Asian European

MANUS – Papua New Guinea 16 Most naturally mesomorphic group yet measured with Heath-Carter somatotype

DINKA - Sudan 17 Most naturally ectomorphic group yet measured with Heath- Carter somatotype Manute Bol (7’ 7” Dinka) Spud Web (5’ 7” African-American) Both former NBA players