Matsigenka and Colonos – Lowland, Peru

John studies cultural dynamics in the Matsigenka and Colono populations. He is particularly interested in cultural norms, i.e., peoples’ beliefs about what constitutes appropriate behavior in contexts such as child-rearing, inheritance, labor, healthcare, and education. We have shown, unsurprisingly, that Matsigenka and Colonos tend to hold different norms in many such contexts. However, the distributions of these norms will almost certainly change over time, especially for the Matsigenka, as their interactions with Colonos outside the park in contexts such as commerce, wage labor, and education steadily increase. Our research suggests that certain types of Matsigenka-Colono inter-ethnic interaction, such as boarding secondary-school education, may have a stronger effect on the loss of Matsigenka-typical cultural norms than do other forms of inter-ethnic interaction, such as wage labor. We developed several hypotheses to explain the observed pattern of norm distributions, including differences in the bargaining power of Matsigenka relative to Colonos during individual-level coordination interactions. To test these hypotheses, we are conducting a longitudinal study of cultural norms and inter-ethnic interaction in the Matsigenka and Colono communities, as well as among Matsigenka boarding-school students and their teachers in Colono towns. One goal of this work is to contribute to a robust mechanistic theory of cultural change at ethnic boundaries. A second, and equally important, goal is to empower minority ethnic groups, like the Matsigenka, to develop strategies for the sustainability of cultural norms that they, collectively, would like to preserve, while at the same time facilitating desired inter-ethnic engagement.

Caissa’s research interests are related to human conceptualizations of, and interactions with, the environment. In particular, her study among the Matsigenka of Manu explores cultural understandings of non-human beings and the role of these understandings in people’s environmental behavior. Her research employs mixed methods, combining qualitative ethnographic and quantitative data collection, to examine the population-level variability and distributions of Matsigenka notions of plants, animals, and other non-human beings, as well as the dynamics of cultural change. She plans to complement her current research by studying these notions among residents of the non-Matsigenka Colono towns around Manu National Park, as well as by studying the processes of acquisition and transmission of environmental conceptualizations, in order to explore the mutual cultural influence of Matsigenka and Colonos. Caissa is also interested in exploring how environmental conflicts that emerge in particular socio-political contexts may be related to encounters between people with conflicting conceptions of the world, and the practices associated with such conceptions. 

A common theme for the research agenda we have developed at this field site relates to gaining a deeper understanding of the complex interactions between changing cultural norms, environmental knowledge, and behaviors, particularly in societies with low-intensity integration into the global market economy. 

With this goal in mind, in November 2020 we established the Culture, Environment, and Health Research Group, with our postdoc Dr. Catalina Fernández, who started at the end of 2020 (with a 1-year gap due to maternity leave). Prior to joining our group, Catalina conducted research on the topic of the evolutionary mismatch between long-term adaptations and changing environmental conditions among contemporary indigenous communities in Chile. She continues this work in parallel with our current projects.

In our group, we investigate how the dynamics of cultural norms, perceptions of the environment, and subsistence practices impact health and concepts of wellbeing. Our first objective is to understand how inter-group interaction affects health, as mediated through environmental perceptions, thereby shedding light on its important role in the evolutionary history of our species. A second objective is to better understand the healthcare needs of local communities, paying attention to their particular conceptions of wellbeing. This work, however, requires long-term ethnographic fieldwork, which was unfeasible until the end of 2022 due to travel and local restrictions imposed by the COVID-19 pandemic. In January 2023, John and Caissa were able to return to the Matsigenka communities, where we began a new empirical study of energy expenditure, caloric intake, and perceptions of dietary change and wellbeing, testing new data collection techniques tailored to the Matsigenka context. For this project, Catalina contributes her particular expertise, and a comparative perspective, on the foodways, nutrition, health and wellbeing of diverse human populations.

Figure 23. Estimated height and weight trajectories. Shown are posterior estimates from the composite height (upper row) and weight (lower row) growth models fit to temporally-dense measurements from U.S. children (red), and temporally-sparse measurements from Matsigenka children (blue). Thin lines are mean posterior trajectories for each individual. Thick red and blue lines are mean posteriors for the mean cumulative trajectories of each ethnic group, as well as the trajectories within each of the three growth phases: infancy, childhood, and adolescence. Corresponding mean posterior mean cumu-lative velocity trajectories in green and orange are decreasing (after age 14) from left to right. From Bunce, Fernández and Revilla Minaya (2022 preprint)

Simultaneously, John, Caissa, and Catalina developed new hypotheses and theoretical mathematical models to study physiological traits that may reflect environmental conditions and cultural changes particular to individual human populations. Using data on age, weight and height collected in previous field seasons among the Matsigenka, together with previously published data from other populations, we developed new models to estimate and compare growth trajectories within and across populations according to growth phase-specific genetic and environmental factors. We interpret these results in light of particular dietary and lifestyle factors of each population. This analysis is currently in the preprint stage. In the coming months, our plan is to apply these models to a worldwide cross-cultural comparison of growth trajectories, collaborating with a network of anthropological fieldworkers to incorporate data from small-scale populations in a wide range of ecologies and market integration contexts. Our aim is to better understand causes of global variation in the tempo and magnitude of growth in our species. Such an understanding will, ideally, allow us to suggest strategies to design better healthcare and nutritional interventions that are effective, culturally sensitive, and population-specific.