Ecogeographic variation across morphofunctional units of the human nose.
Although the internal nose is overwhelmingly responsible for heat and moisture exchange during respiration, external nasal morphology is more commonly cited as evincing climatic adaptation in humans. Here, we assess variation across all four morphofunctional units of the complete nasorespiratory tract (external pyramid, nasal aperture, internal nasal fossa, and nasopharynx) to determine which units provide the strongest evidence of climatic adaptation.



We employ 20 linear measurements collected on 837 modern human crania from major geographic (Arctic Circle, Asia, Australia, Europe, Africa) and climatic (polar, temperate, hot-arid, tropical) zones. In conjunction with associated climatic and geographic data, these morphological data are employed in multivariate analyses to evaluate the associations between each of these functional nasal units and climate.



The external pyramid and nasopharynx exhibit virtually no evidence of climate-mediated morphology across the regional samples, while apparent associations between climate and nasal aperture morphology appear influenced by the geographic (and likely genetic) proximities of certain populations. Only the internal nasal fossa exhibits an ecogeographic distribution consistent with climatic adaptation, with crania from colder and/or drier environments displaying internal nasal fossae that are longer, taller, and narrower (especially superiorly) compared to those from hotter and more humid environments.



Our study indicates that the internal nasal fossa exhibits a stronger association with climate compared to other aspects of the human nose. Further, our study supports suggestions that regional variation in internal nasal fossa morphology reflects demands for heat and moisture exchange via adjustment of internal nasal airway dimensions. Our study thus provides empirical support for theoretical assertions related to nasorespiratory function, with important implications for understanding human nasal evolution.
Center for Anatomical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX, 76107, USA.|Department of Pathology and Anatomical Sciences, University of Missouri, M263 Medical Sciences Building, Columbia, MO, 65212, USA.
Scott D
SD
Maddux
Department of Anatomy, Des Moines University, 3200 Grand Avenue, Des Moines, IA, 50312, USA.
Lauren N
LN
Butaric
Department of Sociology and Anthropology, Metropolitan State University of Denver, Campus Box 28, P.O. Box 173362, Denver, CO, 80217, USA.
Todd R
TR
Yokley
Department of Anthropology, University of Iowa, 114 Macbride Hall, Iowa City, IA, 52242, USA.|Department of Orthodontics, University of Iowa, 114 Macbride Hall, Iowa City, IA, 52242, USA.
Robert G
RG
Franciscus
D000220:Adaptation, Biological; D000389:Air Conditioning; D000885:Anthropology, Physical; D000886:Anthropometry; D005075:Biological Evolution; D001833:Body Temperature Regulation; D002980:Climate; D006801:Humans; D015233:Models, Statistical; D009295:Nasal Bone / Q000033:anatomy & histology* / Q000502:physiology; D009296:Nasal Cavity; D009666:Nose / Q000033:anatomy & histology* / Q000502:physiology; D044469:Racial Groups / Q000706:statistics & numerical data*
air conditioning; climatic adaptation; human evolution; respiration; thermoregulation