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

PEDRO JOSÉ TÓTORA DA GLÓRIAMARIA ANTONIETA COSTA

WALTER ALVES NEVES

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

• San Pedro de Atacama is one of the driest regions in the world

• Excellent conditions for the preservation of archaeological material

Study Area

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

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

• 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

• 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

Tiwanaku´s influence is both religious and economic

Unspecific Infections

• Periostite and osteomyelite (localized or extensive)

• Linked with two main factors:

aggregation and populational density

nutritional intake

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)

Results

• Solcor-3 (Tiwanaku) shows the highest prevalence of unspecific infections

• Solcor-3 (Tiwanaku) shows the highest prevalence of localized periostite and extensive osteomyelite0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

Solcor-3(pre)

Solcor-3(Tiw)

Coyo-3 Quitor-6

Infections

localizedperiostite

extensiveperiostite

localizedosteomyelite

extensiveosteomyelite

0

0,5

1

1,5

2

2,5

3

3,5

4

Solcor-3 (pre) Solcor-3 (Tiw) Coyo-3 Quitor-6

Infections

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

• Osteological paradox : “lesion frequencies cannot be interpreted in a straightforward fashion”

• Better health can be made by worse skeletons

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