Pax Lambayeque? Trauma, interpersonal violence, and environment over 3,000 years in the Lambayeque Valley Complex, Peru

Previous research at archaeological sites in the coastal desert of northern Peru suggests strong human behavioral responses to environmental shifts. For example, at the Huaca de la Luna, Sicán, and the Huanchaquitos-las Llamas sites, paleopathological and stratigraphic analyses suggest that sociopolitical elites organized mass human sacrifices between 550−1450 CE in response to sudden intense increases in precipitation, possibly caused by El Niño-Southern Oscillation events. However, there has not yet been quantitative research into the relationship between non-ritualized violence and precipitation over the longue durée . To investigate the role climate change may have had on driving violence in the Peruvian desert coast outside of episodic sacrifice events, as well as accidental injuries, we modeled the relationship between highland precipitation, El Niño flood frequency, and osteological trauma in the Lambayeque Valley Complex. We pull paleoclimate data from the CHELSA climate simulations, and paleopathological data from the extensive work of the Lambayeque Valley Biohistory Project, yielding a total sample size of 1,659 individuals from a period of over 3,000 years. Ultimately, we detect no strong evidence for an association between environmental factors and interpersonal violence and find that non-ritual violence in the Lambayeque Valley Complex was rare (1.6%). These findings support previous meta-analytical work in the south central Andes, which found similar results in coastal and middle elevation communities. This study not only adds to our understanding of the range of human behavioral responses to climate changes but also proposes the hypothesis that mass sacrifice in the Lambayeque Valley Complex was politico-religious in nature rather than a Malthusian consequence of resource stress.