Collaborative Research: Measuring leaping performance, evaluating its anatomical correlates, and reconsidering the importance of leaping in primate origins and early evolution

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Primate species display a diverse range of adaptations for moving through their environments, and hypotheses about these locomotor patterns have long played a central role in models of primate origins. In this project, the investigators will use an integrative set of analytical techniques to (1) explore the correlation of “leaping related” skeletal traits with leaping performance and (2) assess the evolutionary implications of the resulting correlations in the primate fossil record. This approach is designed to provide validated evidence capable of supporting or refuting the hypothesis that selection for powerful arboreal leaping characterized early primate locomotion. Utilizing research facilities at the Duke Lemur Center and the Cleveland Metroparks Zoo (CMZ), this study will contribute to the debate on the relevance of leaping behavior during early primate evolution by providing quantitative biomechanical data on leaping performance in 19 species of extant primates. The project will enhance K-12 education and outreach via the involvement of high school research interns at Northeast Ohio Medical University and Duke University, as well as public outreach efforts through the teaching of a short course on primate locomotor biomechanics at a local STEM academy and public science events at the CMZ, Duke University’s Darwin Day, and the North Carolina Museum of Natural Science. The project will also provide research training and opportunities for undergraduates, female graduate students, and a postdoctoral fellow. Differing hypotheses about ancestral primate locomotion have long generated strong debate about the predominant selective pressures acting during primate origins. Recent paleontological analyses have been interpreted to suggest that selection for improved leaping was particularly critical during early primate evolution. Hypotheses about the paleobiology of ancestral primates are constrained by a limited understanding of the functional significance of morphological variation in extinct lineages, as fossils currently provide only imprecise clues about behavioral capacity. Robust correlations between morphology and performance are needed to more precisely infer locomotor transitions during primate origins from the anatomical transformations revealed by fossils. Fortunately, leaping biomechanics are relatively easy to characterize, making this a particularly tractable locomotor behavior to study. This research is organized into two specific aims. (AIM 1) Investigators will use high-speed video and force plates to study leaping performance in a diverse sample of extant primates, squirrels, and treeshrews. These data will be combined with morphometric datasets to test hypotheses relating variation in leaping performance to variation in skeletal morphology. (AIM 2) Armed with a deeper understanding of the functional morphology of leaping performance, investigators will use phylogenetic comparative analyses and evolutionary modeling to investigate the selective importance of leaping at the origin of crown primates and during their subsequent evolution. This two-pronged approach will ground interpretations of primate “leaping” morphology with transformational functional specificity, permitting assessment of how morphological changes in the primate fossil record quantitatively affected leaping performance and informing long-standing debates on the ecological context of primate origins. This project is jointly supported by the NSF SBE-BCS-Biological Anthropology and BIO-IOS-Physiological Mechanisms and Biomechanics programs.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.