“A generally accepted hypothesis about stem cells says they replenish tissues and organs, including hair, but they will eventually be exhausted and then die in place. This process is seen as an integral part of aging. Instead Dr. Yi and his colleagues made a surprising discovery that, at least in the hair of aging animals, stem cells escape from the structures that house them. ‘It’s a new way of thinking about aging,’ said Dr. Cheng-Ming Chuong, a skin cell researcher and professor of pathology.” The excellent Gina Kolata in the NYT (Gift Article for ND Readers): Losing Your Hair? You Might Blame the Great Stem Cell Escape. (I suppose this helps explain why so many Americans wear tin foil hats.)