In recent years, we’ve seen a pretty steady drop in serious crime in many American cities. There are several theories to explain the drop – better policing strategies, shifting demographics, economic ups and downs – but none of them seems to provide a full and consistent explanation. In Mojo, Kevin Drum thinks he may have found the villain behind crime (and lower IQs and ADHD): Lead. “When differences of atmospheric lead density between big and small cities largely went away, so did the difference in murder rates.”

Here is the Mojo article.