Ontogenetic and morphological variation in primate long bones reflect signals of size and behavior

Nadell, J.; Elton, S.; Kovarovic, K.

Abstract

Objectives Many primates change their locomotor behavior as they mature from infancy to adulthood. Here we investigate how long bone cross‐sectional geometry in Pan, Gorilla, Pongo, Hylobatidae, and Macaca varies in shape and form over ontogeny, including whether specific diaphyseal cross sections exhibit signals of periosteal adaptation or canalization. Materials and methods Diaphyseal cross sections were analyzed in an ontogenetic series across infant, juvenile, and adult subgroups. Three‐dimensional laser‐scanned long bone models were sectioned at midshaft (50% of biomechanical length) and distally (20%) along the humerus and femur. Traditional axis ratios acted as indices of cross‐sectional circularity, while geometric morphometric techniques were used to study cross‐sectional allometry and ontogenetic trajectory. Results The humeral midshaft is a strong indicator of posture and locomotor profile in the sample across development, while the mid‐femur appears more reflective of shifts in size. By comparison, the distal diaphyses of both limb elements are more ontogenetically constrained, where periosteal shape is largely static across development relative to size, irrespective of a given taxon's behavior or ecology. Discussion Primate limb shape is not only highly variable between taxa over development, but at discrete humeral and femoral diaphyseal locations. Overall, periosteal shape of the humeral and femoral midshaft cross sections closely reflects ontogenetic transitions in behavior and size, respectively, while distal shape in both bones appears more genetically constrained across intraspecific development, regardless of posture or size. These findings support prior research on tradeoffs between function and safety along the limbs.

Citation

Nadell, J., Elton, S., & Kovarovic, K. (2021). Ontogenetic and morphological variation in primate long bones reflect signals of size and behavior. American journal of physical anthropology, 174(2), 327-351. https://doi.org/10.1002/ajpa.24198

• Journal Article Type: Article
• Acceptance Date: Nov 19, 2020
• Online Publication Date: Dec 24, 2020
• Publication Date: 2021-02
• Deposit Date: Dec 4, 2020
• Publicly Available Date: Dec 24, 2021
• Journal: American Journal of Physical Anthropology
• Print ISSN: 0002-9483
• Electronic ISSN: 1096-8644
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 174
• Issue: 2
• Pages: 327-351
• DOI: https://doi.org/10.1002/ajpa.24198
• Public URL: https://durham-repository.worktribe.com/output/1255955