Jacobus SaersVisiting Assistant Professor
I received my PhD in Biological Anthropology from the University of Cambridge, where I subsequently worked as a postdoctoral researcher and lecturer in human evolution. I then spent two years as a Marie-Curie Research Fellow in Vertebrate Evolution, Development, and Ecology at Naturalis Biodiversity Center in the Netherlands before joining Emory University as a Visiting Assistant Professor.
Research
My research integrates evolutionary developmental biology (Evo-Devo), comparative anatomy, and virtual anthropology to explore the evolutionary origins of human morphology and behavior. Building on my doctoral work, where I focused on human variation and skeletal biomechanics, my current research investigates how intersections between evolution, development, and ecology shaped key aspects of human biology, such as locomotion, life history, and skeletal fragility.
Evolution of human locomotion
I am deeply fascinated by the evolution of locomotion. Specifically, my research focuses on understanding how humans became the only apes that do not depend on arboreal locomotion—a skill that is crucial for the survival of all other known living and extinct apes. I use a virtual anthropology approach, CT scanning the fossils of extinct human relatives (hominins) and analyzing aspects of their size and shape to reconstruct their behavior during life. To do this, I have developed new virtual anthropology methods such as an R package to calculate and visualize 3D variation in internal spongy (trabecular) bone structure from CT scans.
Evolutionary and developmental origins of human skeletal fragility
Humans have unusually fragile skeletons, even after accounting for modern sedentary lifestyles. This fragility is most evident in the trabecular (spongy) bone that forms the internal scaffolding of bones and predisposes humans to osteoporosis. By combining developmental and evolutionary evidence that human trabecular fragility is a consequence of delayed motor development —a consequence of slow (secondarily altricial) life history which, in turn, is a byproduct of the evolution of our large brains. Due to our slow acquisition of locomotor ability, humans are essentially born into bedrest during the first year of life. Remarkably, bone loss during this period exceeds that which occurs during spaceflight, leaving humans with a relatively fragile skeletal foundation that increases susceptibility to osteoporosis later in life. Understanding the developmental constraints on human locomotor, brain, and skeletal development allows us to appreciate the evolutionary origins of such health issues and informs strategies for treatment and prevention in contemporary populations.
Selected Publications
Saers, J.P.P., Gordon, A.D., Ryan, T.M., Stock, J.T. (2022). Trabecular bone ontogeny tracks neural development and life history among humans and non-human primates. Proceedings of the National Academy of sciences.,119, (49), e2208772119.
Nishimura, T., Tokuda, I., Miyachi, S., Dunn, J.C., Ishimura, K., Kaneko, A., Kinoshita, Y., Koda, H., Saers, J.P.P., Imai, H., Matsuda, T., Larsen, O., Jürgens, U., Hirabayashi, H., Kojima, S., Fitch, T. (2022). Evolutionary loss of complexity in the human vocal anatomy as an adaptation for human speech. Science. 377, (6607), 760-763.
Saers, J.P.P., DeMars, L.J., Stephens, N.B., Jashashvili, T., Carlson, K.J., Gordon, A.D., Ryan, T.M., Stock J.T. (2021) Combinations of trabecular and cortical bone properties distinguish various loading modalities between athletes and controls. American Journal of Physical Anthropology. 174, (3), 434-450.
DeMars, L.J., Stephens, N.B., Saers, J.P.P., Gordon, A.D., Ryan, T.M., Stock J.T. (2020) Using point clouds to investigate the relationship between trabecular bone phenotype and behavior: An example utilizing the human calcaneus. Journal of Human Biology. 33, 2, 1-16.
