Ashly N. Romero

The right and left side of any primate head can and will likely differ. These differences are called bilateral asymmetry. The random deviations from symmetry that are present in the cranium (fluctuating asymmetry) can tell us how well a primate was able to deal with problems occurring during their development (developmental instability). Using geometric morphometric techniques, I calculate levels of fluctuating asymmetry in primate crania to answer questions about developmental instability in primate taxa and provide better context for primate craniofacial evolution.

Though many articles have been written about stress and asymmetry, no one has used a comprehensive stress measurement to evaluate the relationship between these two factors. Allostatic load is a measure of wear and tear on the body provided by multiple biomarkers from various physiological systems. Myself and my collaborators are among the first to investigate how stress affects skeletal growth and development from the relationship between allostatic load and fluctuating asymmetry. Further, we will be the first to measure a true allostatic load index in rhesus macaques.

How asymmetry changes as an individual ages remains unclear. Does asymmetry increase over the lifespan? Does it decrease due to an ability to compensate through directed bone growth? How does rate of growth and duration of growth influence the amount of asymmetry an individual has? My collaborators and I aim to answer these questions by looking at levels of asymmetry in gorillas and chimpanzees of varying ages. This will help us understand a few of the many influences on asymmetry in the skeleton and even provide insight into how primates handle stress during growth and development.

Pathology occurs commonly in primate populations. Tooth abscesses, tooth loss, osteoarthritis, and many other factors surely influence bone growth and absorption over time leaving differences in shape from the typical cranium structure. But how? How does craniofacial shape change with these pathologies? We are analyzing craniofacial shape in adult olive baboons, which have high rates of craniofacial pathologies, to better understand this relationship. 

Tablet and phone use in recent decades has increased exponentially, which adds frequent strains on the neck as it accommodates the postures required for device viewing. To assess how neck position changes with tablet use, my colleagues and I are investigating variation in cervical vertebrae position related to particular postures associated with tablet use. These same individuals provide the perfect opportunity to assess changes in hyoid position with neck extension and flexion in humans. We are additionally characterizing how the hyoid moves during these postures for tablet use.