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Climate change linked to the collapse of the first Andean states

Climate change continues to pose ever-increasing challenges, extending beyond wildfires and threatening crop growth. But another impact raises concern - the apparent surge in interpersonal violence and homicide rates amid temperature hikes.


What does climate change have to do with the collapse of some of the first Andean states? You would probably say nothing, but experts form the University of California beg to differ. Today’s climate change effects are manifold, leading not only to devastating wildfires and shorter staple crop seasons but also resonating in our economies. Disturbingly, mounting evidence, found in published literature, links elevated temperatures to a spike in violence and homicides.

Climate Change and the Collapse of Andean States

Historically, climate change has been an instigator of conflict. Research out of the University of California, Davis, uncovers a pattern of escalated violence during climatic shifts in the south central Andes from A.D. 470 to 1500. This era, encompassing the Medieval Climatic Anomaly (ca. A.D. 900-1250), experienced rising temperatures, droughts, and the first collapse of Andean states.

In a new study, researchers hypothesize that climate change and the ensuing competition for scant resources likely spurred violence among highland inhabitants in the south central Andes. The evidence? They assessed the rate of head injuries, an archaeological indicator of interpersonal violence, among these populations.

Climate Change and Violence

“Decreased precipitation directly connects to a surge in cranial trauma rates,” states Thomas J. Snyder, a doctoral candidate in the Department of Anthropology’s Evolutionary Wing and the study’s lead author. This observation signifies the significant influence of precipitation-reducing climate change on interpersonal violence rates in the region.


Published on June 5 in Quaternary Research, Cambridge University Press, the study includes co-author Randall Haas, a former member of the same UC Davis lab and current professor at Wayne State University.

Geographical Variations

The findings did not apply to coastal and mid-elevation regions, suggesting their choice of nonviolent adaptations to climate change, or possibly a lack of its impact. These regions also displayed more agricultural and economic diversity, potentially cushioning the impact of climate change. Yet, the researchers propose drought-induced resource scarcity in the highlands as a plausible trigger for their witnessed violence.

Emphasizing the value of studying historical interactions between people and nature, Snyder advocates for this approach to comprehend potential implications of current climate change challenges. If climate change is linked to the collapse of the Andean States, what does that tell us for the future?

“This research highlights the vulnerability of those living in already marginal environments to climate change’s severe impacts,” Snyder notes. “Archaeological research can guide us in predicting and effectively addressing the challenges of those most susceptible to a rapidly changing climate.”

Unearthing Violence in the Andes’ Early History

The UC Davis researchers delved into the early Andean history of violence by analyzing nearly 3,000 skeletal fractures from humans discovered at 58 archaeological sites. They correlated these findings with ice accumulation data from the Quelccaya glacier in present-day Peru, Chile, and Bolivia. Concurrently, the widespread abandonment of Wari and Tiwanaku sites signaled a sociopolitical unraveling following the onset of global climate changes.


The researchers believe the Andean archaeological records, renowned for their exceptional preservation and robustness, present an excellent opportunity to explore human responses to climate variability. Their study revealed a startling correlation: for every 10-centimeter annual decrease in ice accumulation at the Quelccaya glacier, the likelihood of interpersonal violence more than doubled.

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Written by Ivan Petricevic

I've been writing passionately about ancient civilizations, history, alien life, and various other subjects for more than eight years. You may have seen me appear on Discovery Channel's What On Earth series, History Channel's Ancient Aliens, and Gaia's Ancient Civilizations among others.

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