Introduction Lessons / Tutorials
P.S. The strength of bones is not really only proportional to the thickness of the bones. I guess that is why we can strengthen our bones by lifting weights and eating nutritious foods. And the strength of the legs is not necessarily proportional to the weight of the animal either, because an elephant does not have to run or jump like a horse. And a horse does not have to be able to carry load many times (10 to 50 times?) its own weight like an ant.