Life is short, relatively speaking. Human life expectancy in the industrialized world today is just a notch over 80 and as low as 66 in developing nations, while the oldest person whose birth date we can confirm died at just over 122 years old. And since the dawn of civilization, a whole lot of people wanted to push those numbers way higher, trying everything from magical spells, to mercury cocktails, to strategic diets, to experimental supplements. But why hasn’t it worked? What’s the longest theoretical lifespan humans could actually have? And what would we need to do to actually have a shot at living for hundreds or thousands of years?