A fascinating article at ScienceBlog looks at the work of Christiaan Leeuwenburgh into the biochemical mechanisms of aging in the heart. "We discovered that within the heart [mitochondria], there were large increases of the antioxidant defenses ... When you are younger, those antioxidants act like the supermen of your life to eliminate the free radicals. With age, the free radicals begin to win the battle ... In future studies, we want to look at lifelong calorie restriction and lifelong moderate exercise to prevent the breakdown of the [mitochondria]. The reason we are alive is mitochondria. Discovering how they break down is the first step to understanding the mechanisms of aging."