The baffling case of Brooke Greenberg, a 20-year-old who never developed beyond the toddler stage, may provide clues to help scientists unlock the secrets of longevity and fight age-related disorders, such as Alzheimer's, Parkinson's, and heart disease. Brooke, who passed away last Thursday, had the body and cognitive function of a 1-year-old. She didn't grow after the age of 5 — and basically, she stopped aging entirely. "Brooke Greenberg, even after her sad passing, may help to reveal answers to one of the major mysteries in human biology: Why do we age and is there any way to slow or...