Doctoral Dissertation Research: Hard tissue correlates of primate growth rate variation

Arizona State University, Scottsdale AZ

Investigators

Abstract

Growth is a central aspect of a species’ biology, and modern humans are fundamentally different in the timing, duration, and pace of our growth compared to other primates. Understanding when and why the modern human growth pattern evolved is key to understanding part of what makes modern humans unique among primates. This doctoral dissertation project examines the links between variation in primate growth rates and hormonal underpinnings via the pituitary gland and a bony structure, the sella turcica. In doing so, it will develop a novel, non-destructive method for estimating individual growth rates and will investigate the effects of ecology and environment on living primates’ growth rates. The insights into pituitary and sella turcica growth and evolution provided by these data also have the potential to inform diagnoses of abnormal pituitary conditions and the etiology of growth deficiencies or diseases related to pituitary hormones. This project will support graduate training and undergraduate research experiences at Arizona State University (ASU), expanding educational opportunities and providing undergraduates with advanced visualization and 3D processing skills that can be applied to fields as varied as engineering and medicine. In addition, the researcher will communicate project findings through science education outreach activities for student and public audiences. Given the importance of growth, the ultimate causes (or selective pressures) that shape growth rates have long been the subject of research, but the proximate mechanisms that underpin variation in growth rates are less well studied. At the proximate level, body growth is the direct result of hormones produced by endocrine glands such as the pituitary. This project builds upon the relationship between the size of the pituitary, which is positively correlated with growth rate across mammalian taxa, and the sella turcica, the bony structure within which the pituitary gland is housed, to first test whether the size of the nonhuman primate sella turcica reflects body growth rate. This goal will be achieved by pairing 3D cranial morphology data with growth data from well-studied primate populations. Second, this research will assess how aspects of ecology and demography (i.e., ultimate causes such as resource availability, food quality, mortality) relate to living primates’ body growth rates both within the study populations and across a comparative sample of 51 species. It will then assess whether these ecological variables also explain variations in relative sella turcica size. Together, the complementary components of this project will contribute to a better understanding of primate growth. 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.