Today, many of us can take it for granted that our grandparents will live through our childhood—and that our children might get to meet them. Not that long ago, though, that wasn’t so common. Not just because our grandparents didn’t used to live that long, but because so many babies died before their first birthday. In most American communities, infant mortality is a thing of the past. But not in all of them. Dr. Abdul El-Sayed takes us to Detroit to dissect American life expectancy— to understand why it’s declining and why it may never have been as high as it should have been in the first place.