I wonder how long the social mandate had been in effect. Pre-industrial times? With advances in technology and medicine by the time of the episode (and without the mandate) their lifespan could have been in the centuries. They might not have been considered decrepit until a century after hitting 60. In the novel, you were a fully trained and legal adult on your fourteenth birthday. Top predator being disease? Sumner Redstone (chairman of both Viacom and CBS) is 92. To find a US president who was below 60 at the time they left office, we have to go back to William Taft. Edit, it's been pointed out the last line of my post is factually wrong, poor research on my part.