Doctoral Dissertation Research: Oxygen transport and the evolution of high-altitude adaptation in humans

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Several human populations, each with distinct histories, have adapted to harsh high-altitude environments over the course of thousands of years. This doctoral dissertation research project compares the physiologies of two high-altitude populations and assesses the extent to which they have adapted similarly or differently to the same environmental stressor – low oxygen. Using the same methods, measured in populations thousands of miles apart at the same elevation thousands of feet above sea level, the project takes a new approach by measuring how high-altitude adaptations work in people during physical activity. The results of the research build on a large body of previous research on this topic and provide important information about how the high-altitude adaptations in both populations have contributed to their survival over time in low-oxygen environments. The project investigators provide scientific outreach among a local community and incorporate feedback and ideas from study participants into the project. This project also provides training for undergraduate and graduate students from groups historically underrepresented in STEM disciplines.Some highland populations have resided in hypoxic environments for thousands of years, promoting stable evolutionary changes in aspects of their biology related to oxygen transport and delivery. Though exposed to the same selective pressure, these populations exhibit some distinct physiological adaptations, suggesting that certain historical contingencies have shaped different trajectories of trait evolution across geographic space and time. The overall objective of this project is to compare the mechanisms of improved oxygen delivery at high altitude. The central hypothesis that this study tests is that one population improves oxygen delivery primarily through increased blood oxygen content, while the other improves oxygen delivery primarily through increased blood flow. Using refined and carefully matched protocols, this project employs exercise testing, respiratory gas analysis, and hematological measurements in 70 individuals from each population to test this hypothesis. The results of this research contribute to a large body of research on human biological variation in relationship to environmental stressors, importantly through the added perspective of oxygen delivery during the stress of physical activity at high-altitude.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.