Doctoral Dissertation Research: Evolution of the forelimbs of suspensory primates

Biological adaptations are often observed to have evolved multiple times within a group of species. This phenomenon may be related to the occurrence of particular co-occurring traits within a group of species that make the evolution of some adaptations more likely than others. Among primate groups that use suspensory locomotion, this pattern of movement seems to have evolved multiple times independently.

This doctoral dissertation project investigates how covariation among biological traits within the forelimbs of primates affected the trajectory of their evolution. The project contributes to an emerging understanding of how covariation of traits impacts the evolution of new body plans, in particular the evolution of humans’ distinct form of upright walking.

In addition to training a graduate student, this project generates a large dataset that can be used to train undergraduate and high school students in study design, statistics, and computer coding. The doctoral student plans to publish short, public-oriented video abstracts of this project’s results, creating a direct link between active scientists and the public.

This project studies how changes in the way biological traits covary can affect the trajectory of evolution, potentially making specific adaptive suites more common in certain clades while inhibiting their evolution in other groups. The investigator plans to collect 3-dimensional data on the forelimb bones of primates from across the order, use evolutionarily informed statistics to identify traits that are associated with frequent suspensory behaviors, and examine how these traits covary in suspensory taxa and their close relatives using matrices.

Different hypotheses about the evolution of suspension in primates predict different strengths and patterns of trait covariation in suspensory vs non-suspensory groups. The extent to which the common ancestors of humans, chimpanzees, and other apes were adapted for suspension is under active debate. By studying how suspension evolved in primates, this study will contribute to our understanding of early human 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.