Ongoing Research with Native American Tribes:

Restoring Indigenous Socio-Environmental Systems in the Bear River Basin and in the Bears Ears National Monument (RISES) (NSF-DISES). 

Ecological conditions are influenced by exogenous forces, like drought, and by endogenous factors, like human-environment interactions. Over the long-term these dynamics create integrated socio-ecological systems (SES), which have influenced plant and animal distributions across the planet for millennia. The outcomes of long-term SES dynamics are evident today among contemporary Indigenous societies where long-term interactions endure. However, many Indigenous SES have been disrupted by European settler-colonial invasion, forced removal, and genocide, leading to the collapse of Indigenous populations and coupled ecosystems. Understanding Indigenous SES dynamics is crucial for restoring ecosystems. Critically, restoring these dynamics requires active engagement with Indigenous communities, who are typically left out of restoration projects. Our projects (NSF DISES, $600,000 awarded), focused on the Bear River Valley and the Bears Ears National Monument, collaborates with the Northwest Band of the Shoshone Nation, the White Mesa Ute, and the non-profit organization Indigenous Led to quantify long-term SES dynamics, evaluate the drivers of change within these systems, and provide educational opportunities to community members, Indigenous K-12, and university students, all within a collaborative framework of shared knowledge and problem solving.

Ongoing Research in the North American Southwest:

Quantifying long-term exogenous climate and endogenous socio-demographic drivers of conflict in the Precontact Southwest. 

Understanding the socio-climatological conditions that drive conflict is a key scientific initiative and can contribute to developing interventions to mitigate violence. To do so, we need theory to disentangle causes from spurious correlations and case studies to estimate interactions between driving forces. Here, we couple theory from evolutionary ecology with a machine learning statistical approach to evaluate the conditions driving conflict in the precontact Southwest. We leverage a new archaeological dataset from the Bears Ears National Monument to evaluate the direct and interactive effects of precipitation, temperature, climate shocks, demography, and inequality on habitation site defensibility, our proxy for inter-group conflict. We find that conflict peaked during dry, warm conditions when population density and inequality were highest. Results support our theoretical predictions, and suggest cascading effects, whereby xeric conditions favored population aggregation into an increasingly small, heterogenous area, which increased resource stress and inequality and promoted inter-group conflict over limited productive patches. This dynamic likely initiated positive feedbacks, whereby conflict exacerbated shortfalls and fostered mistrust, which drove further aggregation and competition. Results reveal complex interactions among socio-climatological conditions that combined to promote conflict, all of which may have contributed to regional depopulation during the 13^th century AD.  

Intensification, Inequality, and Resilience: The Dynamic Responses of Human-Environment Systems to Climate Change (HNDS-R in-prep). 

Current and future climate change is poised to significantly destabilize the planet’s physical, biological, and social systems forcing humanity to adapt or face widespread crises. Ongoing and future climate crises will impact marginalized subsistence farming communities first, limiting the adaptive resilience options, which are centered in the local natural capital and the latent social capital of their community networks, for these vulnerable populations. However, studies on adaptive resilience are limited by focusing on non-subsistence populations during the last few centuries, when climate was relatively stable. To address these limitations, we will develop a rigorous, network-based framework capable of assessing adaptive capacity under dynamic conditions. To do this, we leverage approaches from the SBE fields of Geography and Archaeology. We apply this framework to a case study on indigenous subsistence farmers, capturing 1750 years of human adaptation to severe climate change; thereby identifying key characteristics in how socio- environmental networks change and respond to impact community resilience. Specifically, we will couple social and climatological factors within a novel, replicable, network-based analysis, to evaluate four key hypotheses about how people utilize investment, exchange, and migration to become more resilient to damaging climate changes. Crucially, this project will create new methodological tools to advance research on how human network connectivity impacts societal resilience and will provide unique insights into past small-scale farmer adaptive responses to climate change similar in scope to our projected climate future. 

Ongoing Research in Mesoamerica:

Climate and Cycles of Collapse and Regeneration in the Central Maya Lowlands. 

Charting the rise and fall of Classic Maya kingdoms has garnered substantial attention but the precise timing of socio-political decline at the end of the Classic period remains one of the least understood aspects of the ‘Classic Maya collapse’. These efforts are especially needed to compare paleoclimate records to archaeological data to identify the coupled effects of climate on political centralization and decentralization. Here we report high-precision AMS ¹⁴C dates on human skeletal remains from ceremonial and residential burials (n=144) to identify the timing of political and demographic changes associated with the rise and fall of regional centers in the Upper Belize River Valley of western Belize. These data offer an unprecedented view of multiple cycles of growth, collapse, and regeneration that spanned the Preclassic to Postclassic periods (age range here). We identify three cycles of population growth and collapse in the 2,000-year sequence that show strong correlations between population change and climatic fluctuations. Political networks, assessed using temporal social network analysis, indicate decline prior to the initiation of multi-decadal drought, though they terminated during a period of severe drought in the ninth century. Terminal Classic decline was more rapid at the site of Cahal Pech, with populations abandoning the center by the ninth century. The riverine settlements of Baking Pot and Lower Dover were more resilient, with populations persisting to the end of the tenth century CE. The Belize Valley remained sparsely populated thereafter until the mid-thirteenth century when burials indicate a cycle of previously unidentified population growth.

The Population Ecology of Early Classic Maya Cities 

The high costs of urbanization in early cities raise the question of why cities first emerged, or more precisely, what socio-ecological conditions favored early urbanization? We draw on simple population ecology models to help illustrate why human populations aggregate into cities. These models describe three non-mutually exclusive pathways to sustained aggregations: 1) environmental heterogeneity coupled with exogenous shocks, 2) returns to scale via protection from inter-group conflict, and 3) realizing latent economies of scale. These models also suggest conditions under which population aggregation may be sufficiently large and sustained to scale to urbanization, and socio-ecological mechanisms that may trigger the reverse process of deurbanization. We test model predictions by coupling paleoclimatological, paleodemographic, and historic data from Classic Maya lowlands city-states (300 – 1000 CE) with piecewise structural equation models. While lowland Classic Maya centers were not the first cities in the region, this paper focuses on developing and testing a general theory of early city formation and dissolution among largely rural agrarian populations - processes that define Classical Maya lowland urbanization and collapse.  

Ongoing Research in the Andes:

Climate stability and low population pressure predict peaceful interactions over 10,000 years of Central Andean history 

As anthropogenic climate change threatens to destabilize global societies and ecosystems, anticipating likely human responses becomes ever more urgent. A key global initiative and U.N. Sustainable Development Goal is the promotion of peaceful interactions and institutions. Nonetheless, studies that systematically quantify and evaluate factors that promote peace are limited, and research focuses on recent centuries when climatic conditions were relatively stable. Here, we couple evolutionary ecological theory with machine learning models to investigate the relative effects of changing climatological, demographic, and socio-political conditions on the persistence of peace over the Central Andean Holocene sequence. We find that stable climate conditions and low population density best predict peaceful interactions, even when average climate conditions are subpar. Given that many climate projection models predict increasing climate volatility in the coming decades, our results suggest that future climate instability may weaken peaceful interactions, particularly among vulnerable subsistence populations in marginal environments. 

Identifying a Starvation Signature in the Nazca Highlands of Peru during the Late Intermediate Period (1000 - 1450 CE)

While the physical effects of interpersonal violence are well-documented in archaeology, its broader impacts on population health and survival strategies are less understood. In modern contexts, chronic warfare is linked with persistent food insecurity and at times population-wide starvation. Identifying harmful outcomes such as starvation in the archaeological record remains a substantial challenge but can be accomplished through the use of coupled biological and isotopic data. This study integrates isotopic, osteological, and paleoclimatic data to assess the interplay between resource acquisition and violence avoidance in the Nazca Highlands during the Late Intermediate Period (LIP; 1000–1450 CE). By analyzing δ¹⁵N, δ¹³C, and δ³⁴S values from 149 radiocarbon-dated individuals, we identified elevated nitrogen isotope levels indicative of population-wide protein shortages, commonly known as the "Starvation Signature." These findings, supported by climate proxies and dietary baselines, align with osteological markers of violence and physical stress, suggesting prolonged resource scarcity and chronic nutritional stress driven by internecine conflict. Our results underscore the complex relationships between conflict, mobility constraints, and resource acquisition, offering insights into how past populations managed sustained stressors.

Publications:

2024, Noe, Sarah J., Weston C. McCool, Kurt M. Wilson. The political and subsistence economic roles of camelid agropastoralism over 2000 years of Andean History. Plos One. https://doi.org/10.1371/journal.pone.0306205

2024, Vernon, Kenneth B., Weston C. McCool, Peter J. Yaworsky, Jerry Spangler, Brian F. Codding. The Fremont Frontier: Living at the Margins of Maize Farming. American Antiquity 89(3), 440 - 458.

2024, McCool, Weston C., Brian F. Codding. U.S. homicide rates increase when resources are scarce and unequally distributed. Evolutionary Human Sciences. doi.org/10.1017/ehs.2023.31.

2023, Arkush, Elizabeth, Weston C. McCool, Ryan Smith. The Late Intermediate period in the south-central highlands: Key problems in timing. In: Leveraging Radiocarbon in the Central Andes: From Chronologies to Research Agendas (Eds., Contreras, D., Marsh, E., Rademaker, K.), Quaternary International. doi.org/10.1016/j.quaint.2023.10.002.

2023, Yaworsky, Peter M., Kenneth B. Vernon, Weston C. McCool, Brian F. Codding. Land use patterns of the west Tavaputs Plateau driven by population expansion and contraction during the Formative Period. In: The Dynamic Influences of Climate Change on Prehistoric Lifeways in the Americas (Eds., Wilson, K.M., McCool, W.C.), Quaternary International Special Issue. doi.org/10.1016/j.quaint.2023.12.003.

2023, McCool, Weston C. Migration, settlement, and warfare in the Nasca highlands of Peru. In: Papers is Memory of Bradley J. Parker (Eds., Kennedy, J., Mullins, P.). Sidestone Press. 

2023, Wilson, Kurt M., Weston C. McCool, Joan Brenner Coltrain. Climatic influences on subsistence intensification along the coasts of the prehispanic Central Andes. Special Issue: The Dynamic Influences of Climate Change on Prehistoric Lifeways in the Americas (Eds., Wilson, K.M., McCool, W.C.). Quaternary International. doi.org/10.1016/j.quaint.2023.07.002.

2023, McCool, Weston C., Amy S. Anderson, Alexis J. Baide, Brian F. Codding. Population pressure and agricultural intensification mediate climatological drivers of chronic childhood stress in the ancient central Andes. Special Issue: The Dynamic Influences of Climate Change on Prehistoric Lifeways in the Americas (Eds., Wilson, K.M., McCool, W.C.). Quaternary International, doi.org/10.1016/j.quaint.2023.06.003.

2023, Macfarlan, Shane J., Ryan Schacht, Weston C. McCool, Connor A. Davis, Anahi D. Yerman, Francisco Javier Higuera Landeros, Maximo Amador Amador. Decision-making under climate shocks and economic insecurity: Ranching in rural Baja California Sur, Mexico. Special Issue: Dispatches from the Field. Evolution and Human Behavior. doi.org/10.1016/j.evolhumbehav.2023.07.001.

2023, Wilson, Kurt M., Weston C. McCool. The Environmental Null: Documenting the changing influence of physical and social environments on prehistoric Andean diets. In: Foodways of the Ancient Andes: Transforming Diet, Cuisine, and Society (Eds., Alfonso-Durruty, M.P., Blom, D.E.). University of Arizona Press.

2022, McCool, Weston C., Kurt M. Wilson, Kenneth B. Vernon. Ecological constraints on violence avoidance tactics: An explanation for high rates of lethal and sublethal violence in the Prehispanic Andean highlands. Environmental Archaeology doi.org/10.1080/14614103.2022.2137652.

2022, Kennett, Douglas J., Marilyn Masson, Carlos Peraza Lope, Stanley Serafin, Richard George, Thomas Spencer, Julie Hoggarth, Brendan J. Culleton, Thomas Harper, Keith M. Prufer, Susan Milbrath, Stanley Russell, Eunice Uc González, Weston C. McCool, Valorie V. Aquino, Jason H. Curtis, Victor Polyak, Norbert Marwan, Mingua Zhang, Andrew Mason, Gideon Henderson, Gerald H. Haug, Mark Brenner, Yemane Asmerom, James U.L. Baldini, Sebastian F. M. Breitenbach, David A. Hodell. Drought induced civil conflict among the Maya. Nature Communications 13: 3911.

2022, McCool, Weston C., Kenneth B. Vernon, Peter M. Yaworsky, Brian F. Codding. Subsistence strategy mediates ecological drivers of human violence. PLoS One 17(5): e0268257.

2022, McCool, Weston C., Brian F. Codding, Kenneth B. Vernon, Peter M. Yaworsky, Kurt M. Wilson, Norbert Marwan, Douglas J. Kennett. Climate change induced population pressure drives high rates of lethal violence in the Prehispanic central Andes. Proceedings of the National Academy of the Sciences 119(17): e2117556119.

2022, Wilson, Kurt M., Weston C. McCool, Daniel A. Contreras, Simon C. Brewer, Joan Brenner Coltrain, Nicole Zamora-Wilson, Ashlyn M. Huggard, Percy J. Schryver, Roxanne F. Lois Lamson, Brian F. Codding. Climate and demography drive 7000 years of dietary change in the Central Andes. Nature Scientific Reports 12(1): 1-16.

2021, McCool, Weston C., Amy S. Anderson, Douglas J. Kennett. Using a multimethod life history approach to navigate the osteological paradox: A case study from Prehispanic Nasca, Peru. American Journal of Biological Anthropology 175(4): 816-833.

2021, McCool, Weston C., Joan Brenner-Coltrain, Aldo Accinelli, Douglas J. Kennett. The character of conflict: A bioarchaeological study of violence in the Nasca highlands of Peru during the Late Intermediate Period (950 – 1450 C.E.). American Journal of Biological Anthropology 174(4): 614-630.

2020, Daniel M. Fernandes, et al., Weston C. McCool, and David Reich. A Genetic history of the pre-contact Caribbean. Nature 590: 103-110.

2020, McCool, Weston C., Daniel C. McCool. We must either protect him or destroy him. In: Vision and Place: John Wesley Powell and reimagining the Colorado River Basin (Eds., Robison, J., McCool, D.C., Minckley, T.). University of California Press. 

2019, McCool, Weston C., Aldo Accinelli, Joan Brenner-Coltrain. Patrones osteológicos de guerra endémica en la Sierra de Nasca durante el Intermedio Tardío (1000-1450 d.C.). In: Actas del VI Congreso Nacional de Arqueología. Lima, Perú: Ministerio de Cultura. 

2019, McCool, Weston C., Peter J. Yaworsky. Fight or Flight: Assessing Fremont territoriality in Nine Mile Canyon, Utah. Special Issue: Territorial Behavior and Ecology (Eds., Codding, B.F., Whitaker, A.R., Stevens, N.E.). Quaternary International 518: 111-121.  

2018, McCool, Weston C., Joan Brenner-Coltrain. A potential oxygen isotope signature of maize beer consumption: An experimental pilot study. Journal of Ethnoarchaeology 10(1): 56-67.  

2017, McCool, Weston C. Coping with Conflict: Defensive strategies and chronic warfare in the Prehispanic Nasca region. Latin American Antiquity 28(3): 373-393. 

2015, Parker, Bradley J., Weston C. McCool. Indices of household maize beer production in the Andes: An ethnoarchaeological investigation. Journal of Anthropological Research 71(3): 359-400. 

In-Review, McCool, Weston C., Kenneth B. Vernon, Ishmael D’Angelo Medina, Joan Brenner Coltrain, Kurt M. Wilson, Brian F. Codding. Socio-climatological drivers of violent conflict in the pre-contact Bears Ears National Monument, Utah. PNAS: Nexus. 

In-Review, McCool, Weston C., Kurt M. Wilson, Brian F. Codding. Socio-climatological drivers of peaceful interactions over 10,000 years of Andean deep history. Science Advances.

In-Prep, Hoggarth, Julia A., Claire E. Ebert, Weston C. McCool, Jaime J. Awe, Brendan J. Culleton, Michael Holton Price, Carolyn Freiwald, John P. Walden, Rafael A. Guerra, Christophe Helmke, Rodney Sturdivant, Matthew Looper, Pete Akers, Sebastian F.M. Breitenbach, Kirsten Green-Mink, and Douglas J. Kennett. Climate and Cycles of Collapse and Regeneration in the Central Maya Lowlands. Target journal: Proceedings of the National Academy of the Sciences. 

In-Prep, McCool, Weston C., Brian F. Codding. Human violence indirectly modifies ecosystems by influencing economic landscape engineering in the pre-contact Southwest. Target Journal: Environmental Archaeology.