Definition: In this task, you are given an abstract of article. Your task is to generate title for this article. Preferred titles are under thirty words.
Input: Life forms that have low body mass can hunt for food on the undersurface of branches or along shear cliff faces quite unperturbed by gravity. For larger animals, the hunt for dinner and the struggle to avoid becoming someone else's meal require rapid movement against gravity. This need is met by the lever function of long bones, three-dimensional masterpieces of biomechanical engineering that, by their material composition and structural design, achieve the contradictory properties of stiffness and flexibility, strength and lightness.1 Material stiffness results from the encrusting of the triple-helical structure of collagen type I with hydroxyapatite crystals, which confers . . .

Periosteal bone formation--a neglected determinant of bone strength.