Doctoral Dissertation Research: Encephalic Arterial Canals and their Functional Significance

Duke University, Durham NC

Investigators

Abstract

The cost of evolving a large brain, like the human brain, is hypothesized to require energetic trade-offs, such that increases in brain metabolism may require reductions in energy used for growth and reproduction. However, additional comparative data on brain metabolism (the rate at which energy is used) are needed to better investigate these potential trade-offs. Because direct measurements are difficult to obtain for most living species and impossible for extinct ones, this doctoral dissertation project will use measurements obtained from skeletal features affected by brain metabolic demands to infer rates of brain metabolism in a broad group of mammals. Comparing how and why mammals may vary in the energy they expend on the brain relative to their body's metabolism will advance knowledge in primate and human biology and brain evolution. This project will generate numerous 3D scans of skulls that will be used for student mentoring and public outreach at Duke University and the North Carolina Museum of Natural Sciences. These data will also be released for public access on the digital archive MorphoSource, which will yield further research and educational utility. Previous studies suggest that the size of foramina that transmit the brain's arteries may be used to predict brain glucose utilization rates in euarchontans. This project aims to further evaluate the use of these foramina to test energetic hypotheses of brain size evolution. Diameters of the transverse foramina (which transmit the vertebral artery) and carotid canals (which transmit the internal carotid artery) will be measured from osteological and 3-D digitized specimens obtained from high-resolution computed tomography scans, respectively, in a broad taxonomic sample of marsupials, glirans, afrotheres, xenarthrans, and some carnivorans. A study of bony canal area and predicted blood flow rate change through ontogeny in a cadaveric osteological sample of humans will also be conducted to further elucidate the relationship between foramen size, brain size, and brain metabolism. Using these data, this project will test the extent to which large brains in primates and other mammals are sustained by increasing the body's metabolic rate. This research will further the understanding of human brain evolution within the context of mammalian brain evolution. 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.