Life span and physiological perturbations: assessment of demographic parameters and linear enamel hypoplasia in past populations

Stress during childhood can be detected by analysing dental enamel defects since they record the occurrence of events that changed the physiological b alance. Strong perturbations can also decrease the individual's resistance to further stressors, or can be more easily scored on individuals whose res istance was low. This load could also lead to shorter life expectancy. Sinc e death may be regarded as the ultimate stress indicator, the present study focuses on the effects of childhood stress on mortality in several Italian samples spanning from the 3rd millennium BC to the Middle Ages (15(th) c. AD). Demographic parameters as life expectancy at age 20, percentage of dea ths in the classes 30-39, 40-49 years and after 50 years of age are correla ted to the mean number of enamel defects from the mandibular canine of both the whole population and the adult segment only. No significant correlatio n can be found between stress and adult mortality when samples are consider ed together, even though a negative trend can be noted when samples are con sidered only in their chronological contexts. Differently, subadults show h igher values of stress than adults. This suggests a more direct effect of s tress on mortality during development, while those individuals who were cap able of reaching the adult age are less influenced by what they suffered fr om during childhood.