The Influence of Leaping Frequency on Secondary Bone in Cercopithecid Primates.

Bone remodeling is at least partially mediated by the mechanical environment created by an animal's behavior. Here, we test the hypothesis that bone remodeling is primarily induced by high magnitude loads, likely encountered during leaping/bounding behaviors. Osteon population density (OPD), osteon cross-sectional area (On.Ar), and relative osteonal area (%HAV) were measured from femoral and humeral midshaft thin sections of four cercopithecids (N = 5 per species) from Taï Forest, Côte d'Ivoire: Colobus polykomos, Piliocolobus badius, Cercopithecus diana, and Cercocebus atys. All species are generalized quadrupeds but vary in leaping frequency and overall activity budget. Differences between taxa with high (C. polykomos and P. badius) and low leaping frequency (C. diana and C. atys) were assessed via a phylogenetically informed generalized linear mixed model using Markov Chain Monte Carlo methods. Femoral OPD and %HAV are greater in the high frequency leapers than in low frequency leapers, suggesting that frequent high magnitude loads engender remodeling, however, there is no similar pattern in the humerus, which presumably also experiences high magnitude loads during leaping. Additionally, OPD and %HAV are greater in the humerus than the femur, despite load magnitude being presumably higher in the femur. These results provide conflicting support for hypotheses about load magnitude and load frequency as they relate to bone remodeling activity. Future work is proposed to parse out the respective effects of load magnitude and frequency on bone remodeling. Anat Rec, 302:1116-1126, 2019. © 2018 Wiley Periodicals, Inc.