Health and disease in the prehistoric Pacific Islands

Abstract

The main impetus of this research was to assess the role of infectious disease, particularly malaria, on the success of human settlement in the prehistoric Pacific Islands. A significant difference in the disease environments of the Pacific Islands is the presence of malaria in most of Melanesia and its absence in Polynesia. This research is the first attempt to assess the impact of malaria on the health of prehistoric Pacific Islanders. The materials used were two samples of human skeletal remains from different regions of the Pacific Islands; one from Taumako, an island in the malarial zone of the Solomon Islands, Melanesia and one from Tongatapu, the Kingdom of Tonga, Polynesia where malaria has always been absent. The objectives of this research were to record several different parameters of health and disease in these samples. Firstly, the demographic profile of each population was compiled to test whether the mortality rates of the Taumako people may have been affected by the presence of malaria. Secondly, non-specific indicators of growth disruption in dental material were recorded to assess whether levels of childhood stress were greater at Taumako. The stature of adults was also compared between Taumako and Tonga as a measure of the individual ability to achieve a genetic potential for growth. Finally, the skeletal indicators of iron deficiency anaemia and infectious disease were recorded to test whether the prevalence of disease differed and whether these differences may be attributed to malaria. The results of the analyses of these parameters of health and disease showed significantly higher prevalences of prenatal and childhood growth disturbance at Taumako compared to Tonga. The stature of adults was similar between the two regions but the range of heights was greater at Taumako. Similarly, a higher prevalence and more severe expression of iron-deficiency anaemia and significantly more proliferative skeletal lesions were found at Taumako. However, a significantly greater number of subadults were affected with postcranial proliferative lesions at Tonga than Taumako, although, the affected children were older at Tonga. The mortality rates of the two populations were similar, although males were more vulnerable to early death than females at Taumako. A differential diagnosis proposed that endemic yaws was the most likely infectious disease causing the skeletal lesions at Taumako; while at Tonga a more non-specific pattern of disease was proposed. The possibility of multiple causes for the skeletal lesions was also proposed for some individuals at both sites. The discussion of the results found they were consistent with the premise that the presence of malaria in Melanesia may have caused chronic growth disturbance and exacerbated the expression of anaemia and infectious disease in prehistory. However, it is also argued that differences in diet may have had an equally strong role in the observed patterns of health and disease. In conclusion, the results of this research did not unequivocally demonstrate the role of malaria on the health of prehistoric populations. However, this study is an initial step in the investigation of the impact of malaria on human populations, while not excluding other factors such as diet.