Bone is a springy and salty wonder that is proving much more functional within the human body than originally thought.
The skeleton is a multipurpose organ, offering a ready source of calcium for an array of biochemical tasks, and housing the marrow where blood cells are born. Yet above all the skeleton allows us to locomote, which means it gets banged up and kicked around. Paradoxically, it copes with the abuse and resists breaking apart in a major way by microcracking constantly. "Bone microcracks, that's what it does," Dr. Ritchie said. "That's how stresses are relieved." [...] But like all forms of health care, bone repair doesn't come cheap, and maintaining skeletal integrity consumes maybe 40 percent of our average caloric budget.
The article leads off with the story of Harry Eastlack, whose body repaired itself with bone-building cells no matter what the injury, essentially giving him a not-so-Wolverine-like second skeleton. Here's a photo I found of Eastlack's skeleton, which is housed at the Mutter Museum of the College of Physicians.
