DEVELOPMENTAL MECHANICS DETERMINE LONG-BONE ALLOMETRY

Evolutionary and developmental factors responsible for the scaling rel ationships observed in animal skeletons are poorly understood. We have created a mathematical model for long bone cross-sectional developmen t which incorporates both intrinsic growth and extrinsic, adaptive bon e modeling in response to changes in bone mechanical strains during on togeny. The model successfully simulates the developing morphology in individual animals and the bone geometric allometric relationships amo ng adults across many species (range from mouse to elephant in size). Our results suggest that long bone scaling characteristics are not a r esult of intrinsic genetic factors but are the result of highly conser ved, extrinsic biophysical processes whereby bone tissue strains modul ate skeletal morphogenesis.