title: Environmental stress increases variability in the expression of dental cusps.
abstract: Teeth are an important model for developmental studies but, despite an extensive literature on the genetics of dental development, little is known about the environmental influences on dental morphology. Here we test whether and to what extent the environment plays a role in producing morphological variation in human teeth. We selected a sample of modern human skulls and used dental enamel hypoplasia as an environmental stress marker to identify two groups with different stress levels, referred to as SG ("stressed" group) and NSG ("nonstressed" group). We collected data on the occurrence and the relative development of 15 morphological traits on upper molars using a standard methodology (ASU-DAS system) and then we compared the frequencies of the traits in the two groups. Overall, the results suggest that (a) stressors like malnutrition and/or systemic diseases have a significant effect on upper molar morphology; (b) stress generates a developmental response which increases the morphological variability of the SG; and (c) the increase in variability is directional, since individuals belonging to the SG have more developed and extra cusps. These results are consistent with the expectations of the current model of dental development.
authors.affiliation: Department of Biological, Geological and Environmental Sciences, University of Bologna, 40126, Bologna, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Riga
authors.forename: Maria Giovanna
authors.initials: MG
authors.lastname: Belcastro
authors.forename: Jacopo
authors.initials: J
authors.lastname: Moggi-Cecchi
mesh_terms: D000704:Analysis of Variance; D000885:Anthropology, Physical; D016022:Case-Control Studies; D002908:Chronic Disease; D003744:Dental Enamel Hypoplasia / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008963:Molar / Q000473:pathology*; D009748:Nutrition Disorders; D013312:Stress, Physiological / Q000502:physiology*
keywords: dentition; development; phenotypic plasticity; variation