Sexual Dimorphism and Regional Variation in Tibetan Head Morphology
Hua Zhong1, Yin Wang2, Hailong Ren3
1Department of Anatomy, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan.
Background:
Human head morphology shows considerable diversity due to evolutionary and environmental factors. Tibetan populations, native to the high-altitude Tibet Plateau, provide a unique context for studying morphologic adaptation. However, comprehensive anthropometric data on their head shape, particularly regarding sexual dimorphism and regional variation in living populations, are lacking.
Methods:
A cross-sectional study was conducted with 508 healthy Tibetan adults (233 men, 275 women) aged 18 to 25 from 4 prefectures. Standard anthropometric instruments were used to measure head length (HL), head breadth (HB), and auricular height (AH). Cephalic indices included the cephalic index (CI), vertical cephalic index (VCI), and transverse cephalic index (TCI). Data were analyzed using nonparametric tests, general linear model analyses adjusting for age, and χ 2 tests.
Results:
Men had significantly greater HL (median: 18.80 versus 17.61 cm), HB (median: 15.60 versus 14.45 cm), and AH (median: 12.00 versus 11.79 cm) compared with women (all P <0.01). Women showed significantly higher VCI and TCI values. Regional heterogeneity was notable in men, particularly in HB and AH in Shigatse and Shannan. Head type distribution differed significantly by sex ( P <0.05): brachycephaly (33.9%) and tapeinocephaly (72.5%) predominated in men, while mesocephaly (32.7%) and brachycephaly (28.4%) were more common in women. Both sexes were predominantly hypsicephalic.
Conclusion:
Young Tibetan adults predominantly exhibit brachycephaly and hypsicephaly, with distinct sexual dimorphism and male-biased regional variation. These patterns likely reflect a combination of cold-climate adaptation, genetic history, and sexual selection. These findings provide clinically relevant morphometric standards for the region.
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