Life forms with low body mass can exploit varied niches and evade predators. The bones provide levers to effect speed and strength while minimizing body mass; the material stiffness of bone derives from the triple helical structure of type 1 collagen encrusted with hydroxyapatite crystals. While this composite structure is strong and light its performance as a biomaterial is critically dependent on ongoing remodeling of microtrauma sustained in the course of daily mechanical stresses.