Meeting Abstract
Physiological climate adaptability is of growing concern given the dramatic increase in human migration over the last two decades. While a narrower nose enhances inspiratory air-conditioning in cold-dry climates, such environments are also metabolically expensive, requiring greater oxygen intake than tropical environments. Accordingly, it has previously been hypothesized that volumetric restriction of oxygen intake due to nasal narrowing may necessitate an increase in nasal height to meet energetic demands. To test this, we employed 17 linear measurements from the nasal skeleton of modern humans from 10 climatically diverse geographic areas (Arctic Circle, Europe, Iran, Australia, North Africa, South Africa, East Africa, West Africa, Papua New Guinea). Femoral head diameter (FHD) was further employed to estimate body size and basal metabolic rate (BMR). In conjunction with climatic data, these morphological data were employed in multivariate analyses to examine the relationship between nasal dimensions, climate, and metabolic demand. Our results indicate that most breadth measurements of the nasal aperture and internal cavity are significantly correlated with climate, but not FHD. Conversely, height and length measurements of the aperture and cavity were found to be more strongly correlated with FHD compared to climate. Further, overall nasal passage area was found to be positively associated with FHD, while nasal passage shape retained a significant relationship with climate. Collectively, these results support the assertion that airway height represents a compensatory mechanism for ensuring a metabolically sufficient intake of oxygen. Additional studies employing more direct measures of metabolic demands are accordingly warranted.
