The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

The effects of locomotor category on the ontogeny of skeletal robusticity in two strepsirrhine species


1Department of Anthropology, George Washington University, 2Department of Orthopaedics, Washington University, 3Department of Orthopaedics, Yale University School of Medicine, 4Department of Surgery, Yale University School of Medicine

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This project investigated skeletal development in nonhuman primates, specifically searching for locomotor and sex differences. We searched for a relationship between bone shape (“robusticity”) and bone quality (density) in Lemur catta and Propithecus verreauxi. A compensatory relationship between bone shape and quality has been shown in humans and mice, whereby gracile bones maintain functional equivalence by increasing tissue mineral density, so we investigated whether it is also present in two species of lemur. Because the pattern has been shown to be sexually dimorphic in humans, we tested for sex differences in adult lemurs, which are less sexually-dimorphic than humans in their body mass. Finally, since the pattern was seen in infant mice, indicating that it is genetic, rather than activity-mediated, we looked for the pattern in infant lemurs.

We microCT scanned eight bones from 11 L. catta and 10 P. verreauxi, which ranged from 0 to 96 months of age. We compared robusticity (i.e., total periosteal area / length) to the tissue mineral density of the bones. The variables were significantly positively correlated due to ontogenetic allometry, but due to small sample sizes, we could not identify the predicted inverse relationship within infants or adults separately. However, Lemur femora were consistently more gracile with higher tissue mineral density than Propithecus femora at all ages, but the reverse was true for the ulna. The site-specific, and at times age-specific nature of the relationship indicates activity patterns may be contributing to the development of both shape and quality aspects of bone strength.

"Funding support for the purchase and analysis of samples from NSF-DGE IGERT 0801634 (PI: B. Wood), and the Lewis N. Cotlow fund at GWU (C. Payette).

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