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Comparison of the Patterns and Degrees of Sexual Dimorphism Among Crania From Late 19th to Early 20th Century West Africans, African Americans, and European Americans

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This study tested the degree and patterns of sexual dimorphism in the crania of West Africans, African Americans, and European Americans who lived in the late 19th to early 20th century, hypothesizing that the degree of sexual dimorphism would be reduced in West Africans living under colonial imperialism compared to marginalized, low-income U.S. populations.
Humans exhibit moderate-to-minimal, and population-specific variance of sexual dimorphism, despite significant size differences between sexes. Nutritional and environmental stresses often influence the degree of sexual dimorphism-especially in the crania. Populations with restricted nutritional access are expected to exhibit less sexual dimorphism. West African data were collected from three museums (male=87; female=47). African- Americans (male=48; female=59) and European Americans (male=22; female=53) were obtained from the Terry collection. The index of sexual dimorphism (ISD) for seven standard measurements of vault and facial dimensions was calculated for each population. The ISD values between populations were analyzed; correlation analyses of the ISDs quantified the degree of similarity in sexual dimorphism patterns for each population. The populations did not significantly vary in their degree of sexual dimorphism (p>0.05), likely due to size overlap between males and females, and high nutritional stress levels in all sampled populations. The populations were also not significantly correlated (p>0.05), suggesting that the overall pattern of sexual dimorphism is unique to each population, and due to genetic and environmental contributions. This research contributes both to practical applications of measuring sexual dimorphism to identify historical stresses, and to theoretical debates on craniometric population variation. (publisher abstract modified)
Date Created: January 28, 2021