A comparative study of activity-related skeletal changes in 3rd-2nd millennium BC coastal fishers and 1st millenium AD inland agriculturists in Chile, South America

Abstract

The reconstruction of patterns of physical activities, behaviour, and lifestyle in past populations is one of the goals most often pursued by bioarchaeologists. This study considers the presence of a group of markers of occupational stress (MOS) that are accepted by many in bioarchaeology as representing the impact of physical activity. To examine their presence, two past populations from northern Chile who practised two contrasting subsistence economies such as marine hunting and gathering with agricultural farmers were compared. The skeletal markers analysed were enthesophytes, osteoarthritis, spondylolysis, os acromiale, osteochondritis dissecans as well as changes in size, shape and robusticity of long bones. The aim of this study was to compare the pattern of these MOS in archaic coastal fishers (3rd-2nd millennium BC) with inland agriculturalists (1st millennium AD). One hundred and seventy-five skeletons of adult males and females curated at the Museo Arqueológico San Miguel de Azapa in Arica, Chile were analysed. It was found that early coastal populations were in general significantly more affected by these MOS when compared with later inland agriculturalists thus suggesting that the archaic way of life based on marine hunting and gathering was more physically demanding than that practised by later agricultural and farming populations. The intra-group analysis between sexes revealed that coastal males showed higher prevalence rates of these markers compared with coastal females but comparisons between agricultural males and females failed to demonstrate any significant difference in the prevalence rates for these markers. Thus suggesting a more marked sexual division of labour among the former group compared to the latter. Inter-group sex comparisons revealed that males from both groups were generally similarly affected by the MOS whereas females displayed a more varied pattern. Assuming that these markers result from physical activity and occupation, regardless of the subsistence economy practised, men from both populations performed the most physically demanding activities. Women on the other hand, would have changed their roles in society with the arrival of agriculture, thus getting progressively more involved and participating more in the demanding tasks required by the agricultural way of life. In conclusion, this study showed that the arrival of agriculture in northern Chile resulted in differences in the patterns and prevalence of activity-related pathological conditions.