Demographic, temporal and environmental effects on the frequency of cribra orbitalia in three Early Medieval populations from western Slovakia

The frequency of cribra orbitalia was examined in Early Medieval skeletal samples from Devín and Borovce (Slovakia). The effects of environmental and socio-economic factors on the distribution of orbital lesions are explored and discussed. The frequency of cribra orbitalia was lowest in Devín-Hrad (11th-12th c. A.D.), followed by Devín-Za kostolom (9th c. A.D.) and Borovce (8th-beginning of 12th c. A.D.). The increased frequency of cribra orbitalia at Borovce can be attributed to inadequate sanitation and increased pathogen load at this rural site compared to urban Devín. Borovce (BO) sub-adults displayed orbital lesions significantly more frequently than BO adults and sub-adults in the Devín-Za kostolom (FR) and Devín-Hrad (DH) samples. Although the total mortality of sub-adults did not differ between the sites, BO sub-adults with cribra orbitalia showed a considerably higher mortality. Their counterparts from FR and DH showed similar mortality patterns irrespective of the presence of orbital lesions. As in most reference samples, no significant sex differences in the frequency of cribra orbitalia were observed in BO, DH and FR. However, a considerably increased mortality was observed in young males from Devín-Hrad irrespective of the presence of orbital lesions. This finding can be attributed to their involvement in violent conflicts. Reference data from Medieval Central European skeletal samples suggest that an increased occurrence of cribra orbitalia was associated with crop failures, migration and interpersonal conflicts. These factors favour the spread of and vulnerability to infectious diseases, which are considered to be the major cause of iron deficiency anaemia.