Ever since Kevin Drum went on his blockbuster tear about lead and violent crime I've been pondering a point Atrios made a bit flippantly. There are presumably other margins on which the same brain chemistry channels operate besides the "violent criminal / not a violent criminal" margin.
And that's exactly what came to mind when I saw David Wessel's chart on America's mysteriously rising high school graduation rate. The falling graduation rate was a bit of a fake puzzle since in objective terms the economic reward to staying in school was rising during this time. But obviously teenagers are often short-sighted in their behavior, so it wasn't a real puzzle. But if teenagers mysteriously started getting less short-sighted at around the same time they started growing up in less lead-poisoned times that certainly seems suggestive.