Climatic adaptation in human inferior nasal turbinate morphology: Evidence from Arctic and equatorial populations

Abstract

Objectives: The nasal turbinates directly influence the overall size, shape, and surface area of the nasal passages, and thus contribute to intranasal heat and moisture exchange. However, unlike the encapsulating walls of the nasal cavity, ecogeographic variation in nasal turbinate morphology among humans has not yet been established.Here we investigate variation in inferior nasal turbinate morphology in two populations from climatically extreme environments.Materials and methods: Twenty-three linear measurements of the inferior turbinate, nasal cavity walls, and airway passages were collected from CT scans of indigenous modern human crania from Equatorial Africa (n = 35) and the Arctic Circle (n = 35).MANOVA and ANCOVA were employed to test for predicted regional and sex differences in morphology between the samples.Results: Significant morphological differences were identified between the two regional samples, with no evidence of significant sexual dimorphism or region-sex interaction effect. Individuals from the Arctic Circle possessed superoinferiorly and mediolaterally larger inferior turbinates compared to Equatorial Africans. In conjunction with the surrounding nasal cavity walls, these differences in turbinate morphology produced airway dimensions that were both consistent with functional expectations and more regionally distinct than either skeletal component independently. Conclusion:This study documents the existence of ecogeographic variation in human nasal turbinate morphology reflecting climate-mediated evolutionary demands on intranasal heat and moisture exchange. Humans adapted to cold-dry environments exhibit turbinate morphologies that enhance contact between respired air and nasal mucosa to facilitate respiratory air conditioning. Conversely, humans adapted to hothumid environments exhibit turbinate morphologies that minimize air-to-mucosa contact, likely to minimize airflow resistance and/or facilitate expiratory heat-shedding. K E Y W O R D S conchae, human variation, nose, respiratory tract, thermoregulation

Nasal cavity and maxillary sinuses form variation among modern humans of Asian descent

“…Importantly, however, these variables cannot provide any information regarding the role of the nasal septum and turbintes, which might be very important (see Holton et al, ; Yokley, ). But form of these structures can only be reliably quantified in CT scans of living subjects (but see Marks, Maddux, Butaric, & Franciscus, ) because in archeological collections the septum and, particularly, the turbinates are severely damaged post‐mortem in most individuals.…”

Ancestry‐based variation in maxillary sinus anatomy: Implications for health disparities in sinonasal disease

“…All CT scans were processed and analyzed using 3D Slicer 4.9.0 (Fedorov et al, 2012). CT-scan processing included the digital rendering of 3D models and reorientation of scans into the Frankfort horizontal position following established protocols (see Butaric, 2015;Butaric & Maddux, 2016;Marks, Maddux, Butaric, & Franciscus, 2019). A total of 29 three-dimensional coordinate landmarks of the MS and surrounding nasofacial skeleton were then collected on each specimen (Figure 2 and Table 2).…”

Common evolutionary patterns in the human nasal region across a worldwide sample

“…The nasal cavity plays a functional role in respiration by humidifying and warming air to facilitate air exchange in the lungs during inspiration in addition to assisting in the retention of moisture during expiration (Bailie et al, 2009; Churchill et al, 2004; Elad et al, 1993; Fukase et al, 2016; Keck et al, 2000; Marks et al, 2019; Naftali et al, 2005; Noback et al, 2011; Yokley, 2009; Zaidi et al, 2017). These functions are determined by the amount of contact between the air and mucosal tissue in the nose, which is dependent on the surface area to volume ratio, residence time (i.e., duration of time when the air is within the nasal cavity), and turbulence (Bailie et al, 2009; Churchill et al, 2004; Marks et al, 2019; Naftali et al, 2005; Noback et al, 2011; Yokley, 2009). The initial inflow tract, consisting of the vestibulum, isthmus and anterior cavum, manages the flow of air toward the consequent turbinates, circulates the air across the surface area of the nose, and decreases the velocity of airflow by adding turbulence (Bastir et al, 2020; Mlynski et al, 2001).…”

“…The initial inflow tract, consisting of the vestibulum, isthmus and anterior cavum, manages the flow of air toward the consequent turbinates, circulates the air across the surface area of the nose, and decreases the velocity of airflow by adding turbulence (Bastir et al, 2020; Mlynski et al, 2001). Since these functions are directly impacted by the form of the external skeletal structures of the anterior cavum, their morphology can influence the operation of the nasal region (Marks et al, 2019; Naftali et al, 2005; Noback et al, 2011).…”