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Climate change intensified violence in the south-central Andean highlands from 1.5 to 0.5 ka

Published online by Cambridge University Press:  05 June 2023

Thomas J. Snyder*
Affiliation:
Department of Anthropology, Evolutionary Wing, University of California, Davis, One Shields Avenue, Davis CA, 95616, USA
Randall Haas
Affiliation:
Department of Anthropology, Wayne State University, 656 W Kirby St, Detroit, MI 48202
*
Corresponding author: Thomas J. Snyder; Email: tjsnyder@ucdavis.edu
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Abstract

The archaeology of the pre-contact Andes provides an ideal study of human responses to climate change given the region's extreme climatic variability, excellent archaeological preservation, and robust paleoclimate records. We evaluate the effects of climate change on the frequency of interpersonal violence in the south-central Andes from ca. 1.5–0.5 ka (AD 470–1540) by comparing incidents of skeletal trauma observed among 2753 crania from 58 sites to rates of ice accumulation at the Quelccaya Glacier. We find that, in the highlands, the odds of identifying inter-personal violence increase on average by a multiplicative factor of 2.4 (1.8–3.2; 95% C.I.) for every 10-centimeter decrease in annual ice accumulation. Our statistical analysis does not detect a relationship between ice accumulation and interpersonal violence rates among coastal or mid-elevation populations. This disparity likely resulted from variable economic and sociopolitical strategies at different elevations. The failure of rain-fed agriculture during periods of drought and concomitant dissolution of organizing polities likely predisposed highland populations to socioeconomic stress and violent competition for limited resources. Conversely, diversity among lowland and midland economies may have buffered against the effect of drought.

Information

Type
Research Article
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.
Copyright
Copyright © University of Washington. Published by Cambridge University Press, 2023
Figure 0

Figure 1. The south-central Andes and sites included in this study. Contour lines present at 500 m asl and 3000 m asl, defining the coastal, mid-elevation, and highland samples (U.S. Geological Survey, 2010).

Figure 1

Figure 2. Quelccaya snow accumulation rates over time (Thompson et al., 1985). Dashed black line indicates average yearly ice accumulation. EIP = early intermediate period, MH = middle horizon, LIP = late intermediate period, and LH = late horizon/Inka imperial period.

Figure 2

Table 1. Cranial trauma and precipitation by archaeological period. EIP = early intermediate period, MH = middle horizon, LIP = late intermediate period, LH = late horizon/Inka Imperial period.

Figure 3

Figure 3. Generalized linear mixed model results, predicting cranial trauma as a function of mean annual precipitation by altitudinal zone. We observe an inverse relationship between interpersonal violence and precipitation within highland contexts, but not mid-elevation or coastal contexts. The frequency of violence ranges from 0–1, where 0 = total lack of violence and 1 = evidence of violence throughout the entirety of the skeletal assemblage. Dots indicate archaeological sites, with dot size indicating sample size, which ranges from 5–277. Lines represent relationship between annual ice accumulation the frequency of cranial trauma, with gray ribbons represent standard error ranges, and dot sizes represent sample size per archaeological site.

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