Systemic Physiological Stress at Chelechol ra Orrak, Palau: Linear Enamel Hypoplasia and Porotic Hyperostosis

Greg C. Nelson* and Scott M Fitzpatrick

The cemetery at Chelechol ra Orrak (ca. 3,000-1,700 Cal BP), Republic of Palau, provides an excellent opportunity to investigate the health of the earliest inhabitants of the archipelago. Here we explore systemic stress as recorded by two pathologies: linear enamel hypoplasia (LEH) and porotic hyperostosis, both cranial (PH) and orbital (cribra orbitalia, CO). A nonspecific stress indicator, LEH develops when the cells producing dental enamel slow, or cease, production, resulting in areas of thin enamel most frequently expressed as lines across the surface of teeth. Unlike LEH, PH has been linked to a single disease process, iron deficiency anaemia, appearing as perforations of the outer table of cranial vault, and can record response to disease from childhood onward. Results reveal a dichotomy in expression between childhood and adult stress. For the childhood markers, LEH appears in 6 of 18 individuals (33.33%) with four recording only one event and only one of 28 “orbital” individuals exhibiting a definite case of CO. In contrast, 19 of 20 crania (95%) exhibit lesions consistent with PH. In general, PH severity is light to moderate and may be indicative of chronic, stabilized, anaemia possibly due to intestinal parasites common in prehistoric peoples consuming marine resources. Although the relatively low rate and light severity of LEH and CO indicates low to moderate levels of systemic stress during early childhood, chronic anaemia in adults can lead to myriad other health problems such as heart and pregnancy related conditions. Implications of the dichotomy will be explored.