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.