Infections in the Subadult Skeletons of San Pedro de Atacama: A Case of the Osteological Paradox?

1. Infections in the Subadult Skeletons of San Pedro de Atacama: A Case of the Osteological Paradox? PEDRO JOSÉ TÓTORA DA GLÓRIA MARIA ANTONIETA COSTA WALTER ALVES NEVES

2. Objective • Main hypothesis: The influence of the Tiwanaku Empire improved the biological quality of life in San Pedro de Atacama • This hypothesis was tested in subadult skeletons from four distinct time periods of the local prehistory • Unspecific bone infections are used as indicators of biological stress

3. Study Area • San Pedro de Atacama is one of the driest regions in the world • Excellent conditions for the preservation of archaeological material

4. Salar de Atacama • The region is located at 2500 meters of altitude • The sites are near the San Pedro River • The oasis are the main locations of human settlement

5. Prehistory of San Pedro de Atacama • 7500 – 1200 B.C.Hunter-gatherers with high mobility and seasonal food resources, hunted camelids and gathered algarrobo and chañar • 1200 – 500 B.C. Beginning of agriculture, pottery production and the domestication of camelids

6. 500 B.C. – 400 A.D. Stable and diversified agriculture (mainly maize), diversification of handcraft production (textiles, metals, basketry, bone tools, pottery) • 400 – 950 A.D. Peak influence of the Tiwanaku Empire: important changes in the social organization and material culture of San Pedro de Atacama Intensification of inter-regional trade, movement of caravans and imported goods from Tiwanaku

7. Tiwanaku´s influence is both religious and economic • 950 – 1450 B.C. Collapse of Tiwanaku Empire; impoverishment of material culture in San Pedro de Atacama; construction of fortifications (pukaras) near the water sources

8. Unspecific Infections • Periostite and osteomyelite (localized or extensive) • Linked with two main factors: aggregation and populational density nutritional intake

9. Material and Methods • Sample of 88 subadult skeletons • Periods: Solcor-3 (before Tiwanaku) 250 – 480 A.D. 39 skeletons Solcor-3 (Tiwanaku) 480 – 920 A.D. 18 skeletons Coyo-3 (final influence of Tiwanaku) 910 – 960 A.D. 18 skeletons Quitor-6 (after Tiwanaku) 920 – 1240 A.D. 13 skeletons • Chi-square test (contingency table 2x2)

10. Results • Solcor-3 (Tiwanaku) shows the highest prevalence of unspecific infections • Solcor-3 (Tiwanaku) shows the highest prevalence of localized periostite and extensive osteomyelite

11. Discussion • Solcor-3 Tiwanaku has the highest prevalence and degree of infections in subadult skeletons • In adult skeletons, those from Solcor-3 Tiwanaku have the highest stature, lowest prevalence of caries and tooth wear • Adult skeletons and archaeological data point to a picture opposite to that suggested by the infections in subadults

12. Osteological paradox : “lesion frequencies cannot be interpreted in a straightforward fashion” • Better health can be made by worse skeletons

13. Conclusions • Inicial hypothesis was not corroborated • We propose that the osteological paradox explains the opposite picture presented by subadult skeletons • Other osteological markers must be analysed to support this interpretation