General Research Themes and Projects
Trabecular Bone Structure and Function
The three-dimensional structure of trabecular bone and its relationship to skeletal loading have been of significant interest to morphologists for some time. Ongoing research in our lab seeks to understand the functional significance of inter- and intraspecific variation in 3D trabecular bone structure in primates and other mammals. Of particular interest is the relationship between trabecular bone architecture and the loads engendered during locomotion in primates. In addition to understanding the functional morphology of trabecular architecture, we have been focusing on the allometric scaling patterns with primates as a way to address the effects of body size on bone structure.
Funding: NSF BCS-0617097
- Ryan, T. M. & Shaw, C. N. (2015) Gracility of the modern Homo sapiens skeleton is the result of decreased biomechanical loading. Proceedings of the National Academy of Sciences, USA. 112:372-377.
- Ryan, T. M., and Shaw, C. N. (2013). Trabecular bone microstructure scales allometrically in the primate humerus and femur. Proceedings of the Royal Society B: Biological Sciences 280:20130172.
- Ryan, T. M., and Shaw, C. N. (2012). Unique suites of trabecular bone features characterize locomotor behavior in human and non-human anthropoid primates. PLoS ONE 7(7):e41037, 11.
- Shaw, C. N., and Ryan, T. M. (2012). Does skeletal anatomy reflect adaptation to locomotor patterns? Cortical and trabecular architecture in human and non-human anthropoids. American Journal of Physical Anthropology 147:187-200.
Ontogenetic Development of the Human Postcranial Skeleton
The ontogenetic development of the human postcranial skeleton is a potentially rich source of information regarding bone functional adaptation and human evolutionary morphology. In collaboration with colleagues from Ohio State University (James Gosman) and the University of Arizona (David Raichlen), our lab is currently analyzing the ontogenetic development of cortical and trabecular bone in the human and nonhuman primate (Pan troglodytes, Macaca mulatta) postcranial skeleton. The relative contributions of locomotor loading, body mass, sex, and age on the development of trabecular and cortical bone structure are being examined, as are the kinematics and kinetics of locomotion during ontogeny in a sample of juvenile modern humans to relate structural changes to changes in locomotion in humans. By quantifying the ontogenetic changes in bone structure across three different primates with divergent locomotor behaviors and developmental trajectories, the role of general developmental processes, genetic patterning, and the mechanical loading environment on bone structure can be more clearly defined. The simultaneous analysis of locomotor development, bone structural and mechanical adaptations, and within and between species variation is unique and should produces a more concrete understanding of bone functional morphology.
Funding: NSF BCS-1028904
Example publications:
- Raichlen, D., Gordon, A., Foster, A., Webber, J., Sukhdeo, S., Scott, R., Gosman, J., & Ryan, T. M. (in press) An ontogenetic framework linking locomotion and trabecular bone architecture with applications for reconstructing hominin life history. Journal of Human Evolution.
- Gosman, J. H., Hubbell, Z. R., Shaw, C. N., and Ryan, T. M. (2013) Development of cortical bone geometry in the human femoral and tibial diaphysis. Anatomical Record 296:774-787.
- Ryan, T. M. and Krovitz, G.E. (2006) Trabecular bone ontogeny in the human proximal femur. Journal of Human Evolution 51:591-602.
Hominin Postcranial Morphology
This project seeks to integrate 3D geometric morphometric approaches to understanding shape variation with biomechanical analyses of diaphyseal cortical bone structure to produce insight into whole bone form and function in the hominin post cranial skeleton. Analyses of cortical bone cross-sectional geometry provide valuable insights into bone structure and associated behavioral patterns in hominins and other primates. Three-dimensional morphometric shape analyses produce insights into shape variation. The goal of this project is to integrate these two types of analyses to generate insights into the structure, function, and evolutionary morphology of the entire hominin lower limb, producing more information than either method provides in isolation. Work on this project is ongoing with collaborators from the University of Cambridge (Colin Shaw, Jay Stock), the Max Planck Institute (Stefano Benazzi), and the University of Bologna (Melanie Frelat).
Funding: NSF IIA-1158603
Example publications:
- Ryan, T. M. & Sukhdeo, S. M. (in press) KSD-VP 1/1 Analysis of the Postcranial Skeleton Using High-Resolution Computed Tomography. In Geology, Chronology, and Anatomy of KSD-VP-1/1, Woranso-Mille, Ethiopia. (Y. Haile-Selassie and Denise Su, eds). Springer Publishing.
3D Imaging and Scientific Visualization
Our research relies heavily on high-resolution computed tomography (microCT) image data to non-destructively access the internal structure of bones, fossils, and other objects. We make use of the industrial high-resolution CT scanner in the Penn State Center for Quantitative Imaging to collect image data at a variety of length scales. These image data allow us to quantitatively characterize a variety of morphological structures in 3D, reconstruct and analyze fossil specimens, and create effective visualizations.
Example publications:
- Ryan, T.M., D.A. Burney, L.R. Godfrey, U.B. Göhlich, W.L. Jungers, N. Vasey, Ramilisonina, A. Walker, and G.W. Weber. (2008) A reconstruction of the Vienna skull of Hadropithecus stenognathus. Proceedings of the National Academy of Sciences. USA 105:10699-10702.
- Simons, E.L., E.R. Seiffert, T.M. Ryan, and Y. Attia. (2007) A remarkable female cranium of the early Oligocene anthropoid Aegyptopithecus zeuxis (Catarrhini, Propliopithecidae). Proceedings of the National Academy of Sciences USA 104:8731-8736.
- Ryan, T.M. and G.R. Milner. (2006) Osteological applications of high-resolution computed tomography: A prehistoric arrow injury. Journal of Archaeological Science 33:871-879.