title: Developmental response to cold stress in cranial morphology of Rattus: implications for the interpretation of climatic adaptation in fossil hominins.
abstract: Adaptation to climate occupies a central position in biological anthropology. The demonstrable relationship between temperature and morphology in extant primates (including humans) forms the basis of the interpretation of the Pleistocene hominin Homo neanderthalensis as a cold-adapted species. There are contradictory signals, however, in the pattern of primate craniofacial changes associated with climatic conditions. To determine the direction and extent of craniofacial change associated with temperature, and to understand the proximate mechanisms underlying cold adaptations in vertebrates in general, dry crania from previous experiments on cold- and warm-reared rats were investigated using computed tomography scanning and three-dimensional digitization of cranial landmarks. Aspects of internal and external cranial morphology were compared using standard statistical and geometric morphometric techniques. The results suggest that the developmental response to cold stress produces subtle but significant changes in facial shape, and a relative decrease in the volume of the maxillary sinuses (and nasal cavity), both of which are independent of the size of the skull or postcranium. These changes are consistent with comparative studies of temperate climate primates, but contradict previous interpretations of cranial morphology of Pleistocene Hominini.
authors.affiliation: Evolutionary Anthropology Research Group, Department of Anthropology, University of Durham, 43 Old Elvet, Durham DH1 3HN, UK. t.c.rae@durham.ac.uk
authors.forename: Todd C
authors.initials: TC
authors.lastname: Rae
authors.forename: Una Strand
authors.initials: US
authors.lastname: Vidarsdóttir
authors.forename: Nathan
authors.initials: N
authors.lastname: Jeffery
authors.forename: A Theodore
authors.initials: AT
authors.lastname: Steegmann
mesh_terms: D000220:Adaptation, Biological; D000818:Animals; D002508:Cephalometry; D003080:Cold Temperature; D005145:Face / Q000033:anatomy & histology; D015186:Hominidae / Q000033:anatomy & histology; D025341:Principal Component Analysis; D051381:Rats; D012886:Skull / Q000033:anatomy & histology* / Q000254:growth & development*; D013045:Species Specificity