Facial Shape Analysis Identifies Valid Cues to Aspects of Physiological Health in Caucasian, Asian, and African Populations

Abstract

Facial cues contribute to attractiveness, including shape cues such as symmetry, averageness, and sexual dimorphism. These cues may represent cues to objective aspects of physiological health, thereby conferring an evolutionary advantage to individuals who find them attractive. The link between facial cues and aspects of physiological health is therefore central to evolutionary explanations of attractiveness. Previously, studies linking facial cues to aspects of physiological health have been infrequent, have had mixed results, and have tended to focus on individual facial cues in isolation. Geometric morphometric methodology (GMM) allows a bottom-up approach to identifying shape correlates of aspects of physiological health. Here, we apply GMM to facial shape data, producing models that successfully predict aspects of physiological health in 272 Asian, African, and Caucasian faces - percentage body fat (21.0% of variance explained), body mass index (BMI; 31.9%) and blood pressure (BP; 21.3%). Models successfully predict percentage body fat and blood pressure even when controlling for BMI, suggesting that they are not simply measuring body size. Predicted values of BMI and BP, but not percentage body fat, correlate with health ratings. When asked to manipulate the shape of faces along the physiological health variable axes (as determined by the models), participants reduced predicted BMI, body fat and (marginally) BP, suggesting that facial shape provides a valid cue to aspects of physiological health.

Keywords: evolutionary psychology; face perception; facial appearance; geometric morphometrics; health perception.

FIGURE 1

Locations of the 138 delineated landmark points. A composite face is shown for illustrative purposes. Faces used in both modeling and rating parts of the study were real individuals.

FIGURE 2

Visualization of linear regression equations: top row is +1 SD and bottom row is -1 SD. Columns correspond (from left to right) to: inverse BMI, normalized percentage fat, blood pressure factor, and health rating.

FIGURE 3

Amount of manipulation (in SD of predicted values) based on regression models chosen by participants to enhance healthy appearance. Error bars show standard error of the mean.