Leonard Hayflick, Ph.D (born 20 May 1928), is an American anatomist, best known for discovering that human cells divide for a limited number of times in vitro (refuting the contention by Alexis Carrel that normal body cells are immortal). This is known as the Hayflick limit. He is a past president of The Gerontological Society of America and was a founding member of the council of the National Institute on Aging (NIA). Hayflick is the author of the book, “How and Why We Age”, published in August 1994 and available in 1996 as a paperback. This book has been translated into nine languages.