Most of things that killed us back in 1900 don’t even crack to the top ten causes of death today. We live way longer and die of a completely different set of ailments associated with that extended life. Now we’re using advances in drugs and science to stave off the effects of those diseases. In the latest in her interesting series on longevity, Slate’s Laura Helmuth looks at one of the hottest debates in science: Just how long can people live?