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

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.

Phenotypic plasticity and constraint along the upper and lower limb diaphyses of Homo sapiens.

Objectives: Morphological variation along the human limb reflects complex structural trade-offs between bone strength and mass. Here we assess how varying levels of plasticity and constraint affect this structure and influence the response to habitual loading along the diaphysis.

Materials And Methods: Cross-sectional geometric properties including total area, cortical area, and rigidity were compared from the upper (humerus: 50% of length, radius: 66%, 50%, 4%) and lower (tibia: 50%, 38%, 4%) limbs of male varsity-level athletes and matched controls with distinct habitual loading histories.