Exploring sexual dimorphism of ancestral cranial nonmetric traits in modern European Americans
Mills, Savannah Rae
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The present study analyzes cranial nonmetric traits used in forensic ancestry estimation on contemporary skeletal remains of modern European Americans in order to determine if there are statistically significant differences between males and females in trait expression. Research on cranial nonmetric traits for ancestry estimation has largely ignored the effects of sexual dimorphism on trait expression; however, there is growing evidence that some traits may be impacted by sex, among other variables. The 17 macromorphoscopic traits described in Hefner and Linde (2018) and the six mandibular morphoscopic traits described in Berg (2008) were scored on 97 females and 113 males from the Texas State University Donated Skeletal Collection in San Marcos, Texas. Chi-square tests were used to analyze if there are statistically significant cranial nonmetric trait expressions between males and females. From these tests, the results indicate that 14 out of the 23 cranial and mandibular nonmetric traits are statistically significantly different between the sexes, with a p-value less than 0.05. Gonial angle flare is the most significant feature, while the zygomaticomaxillary suture is the least significant feature. Additionally, correspondence analyses (CA) show the relationship between each cranial nonmetric trait score, that demonstrated significance, and both sexes. Ultimately, this research demonstrates that several nonmetric traits used in ancestry estimation are affected by sex; thus, it may be beneficial to develop sex-specific ancestry models for nonmetric traits.