1College of Veterinary Medicine, Department of Veterinary Biomedical Sciences, Long Island University, 2Department of Biology, Winthrop University
April 16, 2020 8:00AM, Diamond 2
A fundamental question related to human evolution is when hominins became bipeds and what was the locomotor behavior of humans and chimpanzees’ last common ancestor. Previous research demonstrated that external and internal bone morphology can serve as a source of functional information. The aim of this study was to find whether the size and morphology of secondary osteons, the product of intracortical remodeling, can differentiate between cortical bone regions loaded in compression vs. tension. To this end, we used cross-sections from the proximal diaphysis of seven white tailed deer humeri, a bone that is loaded in bending, as a test case. In each cross-section we quantified the extent of intracortical remodeling and secondary osteon, and central canal size and morphology (circularity). Altogether, 865 and 604 osteons were analyzed in the cranial (loaded in tension) and caudal (loaded in compression) cortices respectively. Our results revealed that except for small periosteal and endosteal areas that contained primary bone tissue, both the cranial and caudal cortices were fully remodeled. While secondary osteon and central canal circularity did not differ significantly between cortices, both were significantly smaller in the caudal (compressive) cortex. Secondary osteonal area was 8,233 µm2 and 14,106 µm2, and central canal area was 354 µm2 and 454 µm2 in the caudal and cranial cortices respectively. These results demonstrate that intracortical remodeling in the compressive cortex forms significantly smaller secondary osteons and central canals, a fact that may help us to infer the locomotion behavior of extinct species.
Study was supported by grants from the National Center for Research Resources and the National Institute of General Medical Sciences from the National Institutes of Health.