Collaborative proposal: Experimental testing of thermoregulatory principles: Re-evaluating ecogeographic rules in living humans

Human morphology varies widely around the world, but claims that adaptive benefits of certain physical features contribute to this variation have rarely been experimentally tested. This research will evaluate how differences in head, trunk, and limb anatomy influence the ability of individuals to regulate their internal body temperature when exposed to different environmental conditions, thereby, experimentally testing long-held assumptions regarding patterning of human body form. The investigators will share the results of this project through publications, STEM outreach activities, public talks, and interviews on a nationally recognized podcast. Graduate, undergraduate, and medical students will be trained in data collection and analysis, and field trip demonstrations of the project equipment and methods will be used to expose economically disadvantaged Texas high school students to potential careers in science and medicine. This project will also produce high-quality, whole body CT scans which will be made readily available to other researchers through an online data archive. Finally, this research will shed light on issues important to both the broader scientific community and the general public, including the significance of human biological diversity and the potential implications of global environmental change.

This research will experimentally test proposed relationships between thermoregulatory benefits and environmentally patterned variation in human anatomy. While climatic pressures are widely cited as contributing to global variation in human head shape, torso dimensions, limb proportions, and overall body size, specific links between physical features and body function in different environmental conditions have not been experimentally established. Furthermore, studies of adaptation to climate have historically focused on separate regions of the body (e.g. braincase, nose, torso, upper limb, lower limb), with minimal attention to how these different anatomical structures interact with one another to function as a whole. To remedy this, the research uses state-of-the-art technologies, including computed tomography imaging and an environmental chamber simulating different climactic conditions, to measure the physiological responses of physically diverse living participants. Validation of proposed thermoregulatory benefits of specific body forms is essential for guiding future research on adaptation. Further, by employing a whole-body approach, this study will clarify the role of different anatomical regions in overall thermoregulatory function. In sum, this study will explicitly link hard and soft tissue morphology to physiological outcomes, permitting more confident assessment of environmental adaptation in both modern populations and the fossil record.

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.