About

I am a biological anthropologist and an Assistant Professor of Anthropology at the University of Massachusetts Boston. Congrats to UMass for being ranked among the top universities worldwide and to UMass Boston for recently cohosting the Behavioral Epigenetics conference with the NY Academy of Sciences!

And, while you’re at it, check out my fantastic UMB colleague and fellow biological anthropologist Dr. Patrick Clarkin’s wonderful blog.

My research is primarily focused on understanding how our dynamic ecological, cultural, and psychosocial environments “get under the skin” to affect health and well-being. I completed my doctoral studies in anthropology at Northwestern University, under the mentorship of members of the Laboratory for Human Biology Research and Cells to Society, The Center on Social Disparities and Health, an affiliate of the Institute for Policy Research. My NSF-funded dissertation research on “Market integration, stress, and health: an exploration of hypothalamic-pituitary-adrenal dynamics among the Tsimane’ of the Bolivian Amazon” is the first to document HPA activity in a foraging population and in the context of a high pathogen, nutritionally marginal environment. My research revealed that although within population variation was consistent with the established correlates of time of day, age, and sex, Tsimane’ cortisol levels are dramatically lower than levels reported in U.S. and industrialized populations (Nyberg 2012, Psychoneuroendocrinology). Moreover, various indices of market integration and acculturation are predictors of variation in cortisol profiles, and demonstrate how factors such as rapid lifestyle change, entry into debt relationships with river traders, and emergent income inequality can increase stress hormones and impact quality of life. Together, these findings reflect the importance of considering political-economic dimensions of globalization and health, and their mediation through unequal social relationships, within a localized cultural and ecological context.

My research also investigates how the HPA axis serves as a key driver of developmental plasticity, coordinating allostasis in diverse ecologies, and mediating competing life-history demands across the developmental trajectory. Informed by related research on reproductive ecology and HPG energetic sensitivity, these findings also raise questions about whether ‘typical’  U.S. diurnal patterns reflect the relatively recent phenomenon of high levels of stress exposures coupled with a positive energy balance, and have important implications for understanding the etiology of stress related disorders such as depression, obesity, and the metabolic syndrome. Population differences in cortisol levels may arise from a variety of factors, (stress exposures? metabolic programming? lower Tsimane’ cortisol as a developmental adaptation to facilitate immune activity in a high pathogen environment? epigenetics? birthweight? exclusive breastfeeding and lots of alloparenting?), and may hold critical insight into why the social gradient in health, now replicated in a diverse array of populations, is relative, especially if stress exposures are calibrated in part, by energy balance. I hope to begin to disentangle this complex nexus of factors in my future research, but at the very least, these findings underscore the contingency of developmental systems, and emphasize that although HPA activity is often used as a proxy of stress, the array of early life, metabolic, nutritional, immunological, psychosocial, and cultural factors that mediate and exert dialectical effects on this hormonal axis are remarkable.

Finally, my research has demonstrated a somatic cost to psychosocial stress in Tsimane’ children, indicating that elevated HPA predicts reduced linear growth rates among children, with downstream consequences for maturation, fertility, and adult health. A manuscript detailing my 2010 HBA presentation of these findings is in preparation and documents that diurnal cortisol rhythms predict differential growth patterns, even when children stunted at baseline (a rough proxy for low birth weight) are excluded from the analyses. From a life history perspective, I also argue that stress should be reframed as a major component of the maintenance energetic budget.

You can find more information about the Tsimane’ Amazonian Panel Study (TAPS) here.

Future directions:

First, the comparatively lower profiles of stress hormones among the Tsimane’ raise the possibility that distinct social, metabolic, and immunologic exposures in early life have lasting impacts on the allostatic regulation of the stress response. To evaluate this, I plan to pursue methods to detect stress hormone receptors on leukocytes from whole blood spots, which will enhance our understanding of how the epigenetic programming of HPA sensitivity is contingent on early immunological priming.

Second, I plan to develop a model of stress of the maternal-fetal dyad that augments my preliminary work on the adaptive role of HPA activity throughout pregnancy, delineates the thresholds at which stress exceeds maternal and fetal buffering capacity, and considers the associated risk for maternal postpartum depression and infant brain development. Given the human pattern of secondarily altricial birth and rapid postnatal brain growth, the HPA axis is well position to have distinct effects in promoting fetal tissue maturation and initiating parturition in a species with considerable metabolic and mechanical stress during the birth process—the ultimate naturalistic reactivity paradigm. And,  considering the role of GCs in shifting the timing of developmental transitions, there is compelling impetus to evaluate the role of the HPA axis in signaling the duration of gestation across primate species, and how these shifts relate to metabolic programming and brain development. This research will appear in a chapter on “HPA activity in pregnant and lactating Tsimane’ women: implications for maternal health and infant brain development” in the forthcoming comparative volume entitled Building Babies: Primate Development in Proximate and Ultimate Perspective (Edited by K. Hinde, K. Clancy, and J. Rutherford, link to review in the International Journal of Primatology June 2013Volume 34Issue 3pp 641-643:  http://link.springer.com/article/10.1007/s10764-013-9676-x#page-1).

Finally, the integration of hierarchical quantitative methods will facilitate the ability to (a) link nested levels of analysis in understanding culture, biology, and differential health outcomes and (b) assess individual change over time. Together, this approach will provide insight into how the HPA axis serves as a key driver of developmental plasticity, coordinating homeostasis in diverse ecologies, and mediating competing life-history demands across the developmental trajectory. This approach is promising in both revealing the depth to which the stress response is regulated at multiple levels, ranging from the ecological, to psychosocial, to hormonal, to epigenetic, and in illuminating the breadth to which macrolevel processes such as market integration and lifestyle change articulate with the interface of health and well-being in contemporary small scale societies such as the Tsimane’.

Degrees:

2009, PhD- Northwestern University

2004, MA – University of Missouri  

2001, BA – Beloit College

Research Interests:  Biocultural anthropology, human biology, evolutionary medicine, acculturation and health in the Global South, psychobiology of stress and HPA function, neuroendocrine-immune interactions, social inequalities and health disparities, growth and development, life history theory, developmental plasticity, human evolutionary biology, statistical methods to assess hierarchical data and longitudinal change

 Geofferey’s ocelot, the Beni, Bolivia

 
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