While the mid-face (the nose and the region around it) is argued to be an aspect of anatomy that is highly constrained by the need to function in respiration, there are obvious differences in mid-facial form between both fossil human species and populations of living humans. The cause of this variation is still not entirely understood. One nasal trait in particular, a distinctly depressed shape to the bottom of the inside of the nose (the internal nasal floor), has previously been argued to be a Neanderthal adaptation to cold climates to help warm inhaled air. Recent research, however, has cast this into doubt. The bones which makes up the majority of the nasal capsule, the paired maxillae, also house the upper dentition and must respond to the competing biological constraints that respiration and mastication place on them. Pilot data for this project indicate that the development of the front teeth during childhood may be the ultimate cause for shape differences in the internal nasal floor. This project by doctoral student Christina Nicholas (University of Iowa), under the supervision of Dr. Robert Franciscus, tests the hypothesis that aspects of the shape of the internal nose, such as internal nasal floor depression versus the lack of depression, are correlated with variation in anterior dental traits. If so, this may imply that some internal nasal traits are a secondary result of evolutionary factors acting upon anterior dental traits (e.g., tooth root size, and timing of tooth eruption). A sample of CT scans of recent humans and 3D surface scans of fossil humans will be analyzed to examine the relationship between internal nasal traits and anterior dental traits.
This research project takes a developmental perspective to investigating mid-facial evolution, with a sample composed of individuals from birth through young adulthood. Little is currently known about the development of internal nasal floor shape, despite the fact that the internal nasal floor plays an important role in pediatric facial surgeries such as the realignment of deviated nasal septa. The results of this project thus have clear relevance not only for biological anthropology, but also clinical areas such as pediatric maxillo-facial surgery and orthodontia. This project also will contribute to training a female scientist.
