1Department of Orthodontics, The University of Iowa, 2Department of Anthropology, The Univeristy of Iowa, 3Department of Sociology and Anthropology, Metropolitan State University of Denver
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Recent studies of the adult human nasal region have documented key differences in nasal capsular form between males and females. These differences are potentially tied to sexually dimorphic differences in body size and energetics. As such, absolute and relative increases in male nasal capsular size are thought to allow for greater oxygen consumption to meet greater daily energy expenditure relative to females. If nasal capsular size is developmentally linked to body size and energetics, we would predict that the sexual dimorphism present in adult nasal form is manifest via different scaling relationships between the nasal capsule and the postcranium during ontogeny. To examine potential male-female scaling differences in nasal capsular size relative to body size, we utilized a combination of cephalometric and anthropometric measurements taken from the Iowa Growth Study at The University of Iowa. We examined male (n=20) and female (n=19) growth allometries of nasal capsular size and facial size relative to upper body dimensions from ages 3-20+ (n=290 total observations). With respect to facial size, there was no significant difference in reduced major axis regression slopes between males and females (P=0.08). In contrast, nasal capsular size in males was characterized by significantly greater positive allometry relative to females as evidenced by significantly different regression line slopes (P<0.001). Thus, as body size increases, males exhibit a disproportionately larger nasal capsule during ontogeny indicating that aspects of nasal capsular size are linked to sexual dimorphism in body size and are potentially associated with differences in oxygen consumption and energetics.