Data from: Geographic variation in chin shape challenges the universal facial attractiveness hypothesis

The universal facial attractiveness (UFA) hypothesis proposes that some facial features are universally preferred because they are reliable signals of mate quality. The primary evidence for this hypothesis comes from cross-cultural studies of perceived attractiveness. However, these studies do not directly address patterns of morphological variation at the population level. An unanswered question is therefore: Are universally preferred facial phenotypes geographically invariant, as the UFA hypothesis implies? The purpose of our study is to evaluate this often overlooked aspect of the UFA hypothesis by examining patterns of geographic variation in chin shape. We collected symphyseal outlines from 180 recent human mandibles (90 male, 90 female) representing nine geographic regions. Elliptical Fourier functions analysis was used to quantify chin shape, and principle components analysis was used to compute shape descriptors. In contrast to the expectations of the UFA hypothesis, we found significant geographic differences in male and female chin shape. These findings are consistent with region-specific sexual selection and/or random genetic drift, but not universal sexual selection. We recommend that future studies of facial attractiveness take into consideration patterns of morphological variation within and between diverse human populations.普遍面部吸引力（Universal Facial Attractiveness，UFA）假说提出，部分面部特征因可作为配偶质量的可靠信号而受到全球范围内的普遍偏好。该假说的核心证据来自针对面部感知吸引力的跨文化研究，但此类研究并未直接探讨种群层面的形态变异模式。因此存在一个尚未解答的问题：如UFA假说所暗示的那样，受普遍偏好的面部表型是否在地理分布上保持恒定？本研究旨在通过分析颏部形态的地理变异模式，对这一常被忽视的UFA假说维度进行验证。我们从覆盖9个地理区域的180件现代人类下颌骨（其中男性90件、女性90件）中采集了颏联合轮廓数据；采用椭圆傅里叶函数（Elliptical Fourier Functions）分析量化颏部形态，并通过主成分分析计算形态描述指标。与UFA假说的预期相悖，本研究发现男性与女性的颏部形态均存在显著的地理差异。上述结果与区域特异性性选择或随机遗传漂变的理论相符，但与普遍性性选择的预测不符。我们建议未来的面部吸引力研究应将多样化人类种群内部及种群间的形态变异模式纳入考量范畴。