Why are some among the aging still having an upward professional trajectory and others babbling, long out of the game? We witness Rupert Murdoch, Warren Buffett, and Betty White enhancing their brandnames and earnings. The first two are in their 80s and the last one is in her 90s.
The answer to that riddle is presented in book "The Scientific American Healthy Aging Brain" by Judith Horstman. The reality is that people age differently and at different rates. The man who needs a knee replacement might not have to undergo that surgery until he is in his late 80s. Another man may die at 101 without having experienced one health problem, including extensive short-term memory loss.
The book also reinforces the notion that there is such a thing as the late bloomer. That is, someone whose genius emerges after 50. University of Chicago professor David W. Galenson had done extensive research on that phenomenon. In 2006, he published the book "Old Masters and Young Geniuses."