title: Is the area of the orbital opening in humans related to climate?
abstract: OBJECTIVE
  The aim of this study was to evaluate whether climatic conditions impact the size of the anterior orbital opening in humans. The previous research has shown that morphology of the human orbit, a trait strongly related to the shape of the cranium, varies significantly among populations. However, the mechanisms of this variation are still debatable. Besides such evolutionary forces as genetic drift, climatic conditions may be involved. Thermoregulatory processes affect skull shape, and thus may also influence orbital morphology.
  
  
  METHODS
  A total of 846 dry skulls of male and female adults from three climatic areas (i.e., warm, temperate, and cold) of Europe were evaluated. The areas of the left and right orbital openings were measured using the three-dimensional contact scanner MicroScribe G2L, and analyzed with regard to climate.
  
  
  RESULTS
  The results reveal a statistically significant association with climatic conditions on the area of orbital opening in accordance with Bergmann's rule. The anterior orbital opening area was smaller in male individuals from the cold climate, and larger in individuals from the warm climate areas.
  
  
  CONCLUSIONS
  These data may support the hypothesized association between size of the orbital opening and adaptation to different climatic conditions, but only in males.
authors.affiliation: Department of Anthropology, Institute of Biology, Wroclaw University of Environmental and Life Sciences, Wrocław, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Tomaszewska
authors.affiliation: Department of Anthropology, Institute of Biology, Wroclaw University of Environmental and Life Sciences, Wrocław, Poland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Kwiatkowska
authors.affiliation: Department of Anatomy, Histology, and Anthropology, Faculty of Medicine, Vilnius University, Vilnius, Lithuania.
authors.forename: Rimantas
authors.initials: R
authors.lastname: Jankauskas
mesh_terms: D002980:Climate; D005060:Europe; D005260:Female; D006801:Humans; D008297:Male; D009915:Orbit / Q000033:anatomy & histology*; D012737:Sex Factors; D012886:Skull / Q000033:anatomy & histology; D013696:Temperature