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

OBJECTIVES: This study explores variation, covariation, and ecogeographic pattern of the nasal cavity, maxillary sinuses, and external midfacial skeleton across 15 populations of east Asian origin inhabiting the Far East, Siberia, Alaska and Greenland. MATERIALS AND METHODS: We have collected linear measurements of the internal nasal cavity, maxillary sinus and external midfacial skeleton as well as volumes and surface areas of three-dimensional models of the cavity. A set of seven climatic variables, mtDNA and Y-chromosome genetic matrices and a matrix of geographic distances were also utilized. RESULTS: A strong association between form of the nasal cavity and climate was found, whereby all north Asian groups display increased volumes, areas and lengths of the cavity, and surface area to volume ratios (SA/V). Most of Siberian groups exhibit not only large and long, but also wide and tall nasal cavity. The Eskimo-Aleutian speaking groups possess cavities that are vertically short and narrow but of a high SA/V ratio. The sinuses exhibit an exceptionally high level of within- and between-group variation which supports the views on the sinus as an architectural byproduct. Both volume and area of the nasal cavity can be reliably estimated based on a set of simple and repeatable linear measurements. DISCUSSION: While the nasal cavity and maxillary sinus are both larger in a larger facial skeleton, there is a strong inverse relationship between them at a given facial size. Our results do not support the notion that the shape of the internal nasal cavity is more strongly associated with climate compared to the external midfacial morphology.

The association between mid-facial morphology and climate in northeast Europe differs from that in north Asia: Implications for understanding the morphology of Late Pleistocene Homo sapiens.

The climate of northeastern Europe is likely to resemble in many ways Late Pleistocene periglacial conditions in Europe, but there have been relatively few studies exploring the association between climate and morphology in the mid-face of modern northeastern European populations. To fill this gap, we sampled 540 male skulls from 22 European and Near Eastern groups, including 314 skulls from 11 populations from northeastern Europe, to test for possible climate-morphology association at the continental scale. Our results found a moderate and highly significant association (R = 0.48, p = 0.0013, Mantel test) between sets of 23 mid-facial measurements and eight climatic variables. A partial least squares analysis revealed this association to be mostly driven by differences between groups from northeastern Europe and populations from the Mediterranean and the Caucasus. Matrices of between-group genetic distances based on Y-chromosome and mtDNA markers, as well as cranial non-metric and geographic distance matrices, were used to control for the possible influence of shared population history. Irrespective of which measure of neutral between-population distances is taken into account, the association between cranial variables and climate remains significant. The pattern of association between climate and morphology of the mid-face in western Eurasia was then compared to that in east and north Asia. Although differences between the two were found, there were also similarities that support existing functional interpretations of morphology for the bony parts of the upper airways. Last, in a preliminary analysis using a reduced set of measurements, mid-facial morphology of several Upper Paleolithic European Homo sapiens specimens was found to be more similar to groups from northern and northeastern Europe than to southern European populations. Thus, the population of northeastern Europe rather than east and north Asian groups should be used as a model when studying climate-mediated mid-facial morphology of Upper Paleolithic European H. sapiens.

Testing the association between human mid-facial morphology and climate using autosomal, mitochondrial, Y chromosomal polymorphisms and cranial non-metrics.

OBJECTIVES: To figure out which and how many systems of genetic markers should be used to control for the effects of shared population history in studies examining the association between morphology and climate and to test cranial non-metric traits as an additional source of neutral distances for such studies. MATERIALS AND METHODS: We employed three systems of genetic markers (mtDNA, Y-chromosome and autosomal SNPs) and cranial non-metrics to control for potential impact of population history on apparent associations between climatic variables and mid-facial morphology found in a set of seven North Asian and one East Asian populations. RESULTS: A significant association between morphology and climate remained, independent of which of the four neutral distance matrices were used as a control. Matrices of neutral distances based on different systems of genetic markers show just one case of significant correlation among each other namely between the mtDNA and autosomal SNPs matrices. The correlation between the autosomal SNP and cranial non-metrics matrices is also fairly high but does not reach significance. DISCUSSION: A combination of several sources of genetic information could provide a more robust control for the effect of shared population history compared to just one type of markers since each of them has its own sources of bias and each provides a slightly different view of genetic relationships among the populations. Use of cranial non-metrics in researches examining the association between morphology and climate appears promising as they produce results that are generally consistent with those obtained using genetic markers.