This study used cross-sectional CT data of three morphologically distinct samples (African, European, Arctic) spanning from infancy to adulthood (total n = 321) to capture 18 landmarks of external and internal regions of the face and nose, using generalized Procrustes and form-space principal component analyses (separately conducted on global and individual samples) to ascertain when adult-specific nasal morphology emerges during ontogeny.
Although internal nasal cavity morphology has long been thought to reflect respiratory pressures related to heating and humidifying inspired air, despite the widely recognized importance of ontogeny in understanding climatic and thermoregulatory adaptations, most research on nasal variation in modern and fossil humans focuses on static adult morphology. Across the global sample, PC1 (67.18 percent of the variation) tracks age-related size changes regardless of ancestry, while PC2 (6.86 percent) differentiates between the ancestral groups irrespective of age. Growth curves tracking morphological changes by age-in-years indicated comparable growth trajectories across all three samples, with the majority of nasal size and shape established early in ontogeny (<5 years of age). Sex-based trends were also evident, with females exhibiting a more truncated growth period than males, particularly for nasal height dimensions. Differences are also evident between the anterior and posterior nose, with the height and breadth dimensions of the anterior nasal aperture and nasal cavity showing differential ontogenetic patterns compared to the choanae. Cumulatively, these results suggest that multiple selective pressures influence human nasal morphology through ontogenetic processes, including metabolic demands for sufficient oxygen intake and climatic demands for adequate intranasal air conditioning. (publisher abstract modified)