Enamel defects at Roonka, South Australia: indicators of poor health or the osteological paradox?

Skeletal evidence of health during the Holocene in south-eastern Australia has contributed to discussions on the mobility and population size of peoples living on the Murray River. One argument is that peoples living on the Murray River experienced poor health evidenced by high frequencies of physiological stress indicators in human remains (enamel hypoplasia, cribra orbitalia, and Harris lines). However, this is not the only explanation for the high frequencies of stress indicators found in these human remains. An alternative but not mutually exclusive interpretation is that individuals with many stress markers such as enamel hypoplasia are the survivors of childhood stressors, and therefore reflect the ability of an individual to overcome periods of physiological stress. The paradoxical interpretation that better health can make for worse skeletons is part of the osteological paradox. These contradictory interpretations can be tested through the analysis of enamel hypoplasia (EH) at Roonka, a large Aboriginal burial site on the Murray River (8,000–200 BP). Survival analysis identifies the mortality consequences of having an enamel defect. This type of analysis allows for a better understanding of the risk associated with having a defect, or multiple defects, in relation to age at death. Age at death and the number of defects was recorded for 130 individuals. The results suggest that, while enamel defects are prevalent among the human remains from Roonka, EH is not associated with an increased risk of death. Results demonstrate that aspects of the osteological paradox are at play in interpretations of enamel defects at Roonka. These results provide evidence that caution is needed when using EH frequency data to argue about past population health.