Porotic Hyperostosis as stress indicator: the state of the art

For well over a century, porosity of the cranial vault and of the orbital roofs have been interpreted by bioarchaeologists as stress indicators. These conditions are commonly reported as Porotic Hyperostosis (PH), but other terms such as cribra cranii and cribra orbitalia have also been utilized. In recent research, cribra orbitalia is considered a distinct phenomenon probably with different etiology, while PH is used to indicate porosity and thinning of the outer cranial table associated with hypertrophy of the diploe. PH has been reported as stress indicator and the nature of this condition is still debated: from the interpretation of PH as nutritional stress marker, as indicator of chronic iron deficiency, or as environmental pathogen load and bad hygienic conditions, up until to consider PH as the expression of well-defined diseases such as anemia and scurvy. The last lines of research provide convincing evidence that hemolytic and acquired anemias are the most relevant disorders causing PH. In particular, acquired forms of anemia can be related to several factors such as dietary deficiency, parasitism, infections, hemorrhage, or other disorders, thus providing the basis for conclusions that PH can be considered an indicator of lifestyle and health conditions. In this research, a re-examination of the literature regarding PH was performed to achieve the state-of-the-art of PH as stress indicator in ancient populations and taking stock of the methodology addressed to record this pathological condition. The most evident criticism is that PH is not characteristic of a specific disease but rather it represents a morphological feature; the porosity on the cranial vault or in the orbital roofs are thus not a sufficient condition to diagnose PH. X-ray, and in some cases histological examination, are need to perform an appropriate differential analysis. For these reasons, the relationship between porosity on the ectocranial surface or on the orbital roofs and environmental stress or poor life conditions should be better evaluated.