Investigating the case of human nose shape and climate adaptation

PLoS Genet. 2017 Mar 16;13(3):e1006616. doi: 10.1371/journal.pgen.1006616. eCollection 2017 Mar.

Abstract

The evolutionary reasons for variation in nose shape across human populations have been subject to continuing debate. An import function of the nose and nasal cavity is to condition inspired air before it reaches the lower respiratory tract. For this reason, it is thought the observed differences in nose shape among populations are not simply the result of genetic drift, but may be adaptations to climate. To address the question of whether local adaptation to climate is responsible for nose shape divergence across populations, we use Qst-Fst comparisons to show that nares width and alar base width are more differentiated across populations than expected under genetic drift alone. To test whether this differentiation is due to climate adaptation, we compared the spatial distribution of these variables with the global distribution of temperature, absolute humidity, and relative humidity. We find that width of the nares is correlated with temperature and absolute humidity, but not with relative humidity. We conclude that some aspects of nose shape may indeed have been driven by local adaptation to climate. However, we think that this is a simplified explanation of a very complex evolutionary history, which possibly also involved other non-neutral forces such as sexual selection.

MeSH terms

  • Adaptation, Physiological / genetics*
  • Africa
  • Asia
  • Asian People / genetics
  • Black People / genetics
  • Climate*
  • Europe
  • Female
  • Genetic Drift
  • Genetics, Population*
  • Geography
  • Humans
  • Humidity
  • Male
  • Nose / anatomy & histology*
  • Selection, Genetic
  • Temperature
  • White People / genetics

Grants and funding

This work was supported in part by the United States National Institute of Justice, the United States Department of Defense, the University of Illinois Interdisciplinary Innovation Initiative Research Grant, the Flemish Institute for the Promotion of Innovation by Science and Technology in Flanders (IWT Vlaanderen), the Research Program of the Fund for Scientific Research - Flanders (Belgium), and the Center for Human Evolution and Development at Penn State. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.