Geometric Morphometric Study of ear Shape in Four Chinese Ethnic Minority Populations

This study aimed to investigate how ear shape in adults changes with age and ethnicity among four Chinese minority groups: Buyi, Tibetan, Tu, and Salar.

We employed a combined approach using linear measurements and 2D geometric morphometrics to comprehensively assess ear shape variation.

Our findings revealed a significant effect of age on ear shape, independent of overall size. Specifically, older adults exhibited a slender helix and antihelix especially in the lower region. Interestingly, the helix showed elongation, while the antihelix became shorter, and the tragus position shifted upwards. While linear measurements increased with age, the overall size (centroid size) remained constant. Although ethnicity displayed greater variability in ear shape compared to age and size, our analysis using Principal Component Analysis and random forest models did not reveal statistically significant differences between the four ethnic groups.

This study suggests that genetic factors play a relatively minor role in shaping ear variation, similar to other cranial features.