A three-dimensional study of sexual dimorphism in the human face

The sexual dimorphism in three-dimensional facial form (size plus shape) was investigated in a sample of 40 men and 36 women by using Euclidean-distance matrix analysis. Subjects ranged in age from 19 to 32 years, had excellent dentitions, and had no craniocervical disorders. For each subject, 16 facial landmarks were automatically collected using a computerized system consisting of two infrared CCD cameras, real-time hardware for the recognition of markers, and software for the three-dimensional reconstruction of landmarks' x, y, z coordinates. Euclidean-distance matrix analysis confirmed the well-known size difference between adult male and female faces (men's faces being 6% to 7% larger than women's faces), while it demonstrated no significant gender differences in three-dimensional facial shape. This result contrasted with the shape differences previously found when separate two-dimensional frontal and sagittal plane projections were analyzed. It could be explained by a relative three-dimensional compensation between the different facial dimensions.