What evidences shows that bones are alive?

There are several evidences that show that bones are alive:

1. Bone cells: Bones are composed of living cells, including osteoblasts, osteocytes, and osteoclasts. Osteoblasts are responsible for building new bone tissue, osteocytes maintain the bone matrix, and osteoclasts break down and remodel bone tissue.

2. Bone growth and remodeling: Bones grow and remodel throughout life. In children, new bone tissue is added to the ends of long bones, allowing them to grow in length. In adults, bone remodeling occurs continuously, with old bone tissue being broken down and replaced with new bone tissue. This process helps to maintain the strength and integrity of the skeleton.

3. Fracture healing: When a bone is fractured, the body initiates a healing process that involves the formation of new bone tissue. This process is a complex cascade of cellular events which results in the formation of a callus, a mass of new bone tissue that bridges the gap between the fractured bone ends.

4. Blood supply: Bones are richly supplied with blood vessels that provide oxygen and nutrients to the bone cells. The blood supply also helps to remove waste products from the bone tissue.

5. Innervation: Bones are also innervated by nerves, which provide sensory feedback to the brain. This allows the body to sense pain and other sensations from the bones, such as pressure or temperature changes.

6. Metabolism: Bones are metabolically active, meaning that they participate in a variety of metabolic processes. For example, bones store calcium and phosphorus, and they also release these minerals into the bloodstream as needed.

These evidences collectively demonstrate that bones are not simply inert structures, but rather living tissues that play an active role in the body's overall function and homeostasis.