One hundred years is a reasonable expectation for most people alive today. One hundred twenty is our known potential and one that many people could reach—again, in good health if technologies in development come to fruition. If epigenetic reprogramming reaches its potential or someone comes up with another way to convince cells to be young again, 150 might even be possible for someone living on this planet with us right now. And ultimately there is no upward biological limit, no law that says we must die at a certain age.