In Latin America, changing socio-political systems, economic, and ecological circumstances are influencing the transition from more traditional subsistence-level lifestyles to more "modern" ones that are characterized by greater integration into the global market economy. This study will investigate how ecological factors and market integration influence energy balance and reproductive function in an indigenous lowland Bolivian population. This will allow a better understanding of the effects of culture change and the integration of traditional groups into the larger market economy. The specific objectives of this study are as follows: 1) explore the impact of market integration on seasonal changes in energetics through measures of nutritional status, dietary composition, physical activity levels, and leptin (an energetic hormone) levels among the Tsimane, 2) examine the changing rates of fertility and fecundity (reproductive capacity) in response to seasonally varying ecological conditions among Tsimane women and 3) evaluate the role of leptin as a mechanism linking reproductive function to various energetic conditions. To pursue these objectives, fieldwork will be conducted for one year, in order to capture seasonal variation, among the Tsimane, an indigenous lowland South American population currently undergoing varying levels of market integration. The following data will be collected to address the goals of the research project: demographic data, ethnographic data, socio-economic data, anthropometrics (height, weight, body composition), basal metabolic rate, total energy expenditure, dietary intake, leptin levels, and ovarian steroid levels (estrogen and progesterone). The scientific merit of this proposal is that it examines questions that cross multiple fields. This project will provide a clear picture of how culture change and market integration affect indigenous people. This research will also contribute to the fields of demography and reproductive science by helping us to better understand the influences of ecological and hormonal factors on measures of reproductive health and fertility in non-westernized populations. In particular, the examination of the hormone leptin adds to our limited understanding of the hormone across various physiological and ecological conditions. The broader impacts of this project have significance across many levels. A greater understanding of the effects of market integration could potentially lead to a decrease in the disruptive effect such integration may have upon indigenous groups worldwide. A greater understanding of energetics and changing adiposity levels could have wide-ranging effects, considering the ever increasing rate of obesity not only in developed countries, but developing areas as well.
