At Mother Jones, Kevin Drum has an in-depth article on the hypothesis that environmental lead is a likely root cause of the increase in crime a generation ago. Even more importantly, removal of lead from gasoline may be responsible for the decrease in crime in the last few decades. Last night, Kevin and I discussed these ideas with Jay Ackroyd on Virtually Speaking.
Support for the environmental-lead/crime association has been building for some time, as described for example in these articles by Rick Nevin and David Carpenter. Two key elements are there: (1) historical epidemiological data from many countries, and (2) a plausible biological mechanism (PDF): effects of lead on the developing brain, especially the prefrontal cortex, and on IQ.
This two-pronged argument is reminiscent of the linkage between smoking with cancer. I find it considerably more persuasive than the speculation by Steven Levitt (Freakonomics) that legal abortion was responsible for decreases in crime. That idea is based on just one study, lacks a convincing mechanism, and does not account for earlier increases in crime, which the lead hypothesis does.
After Kevin left, Jay and I continued our discussion, branching off into child development, individuality, and many other topics from my book Welcome To Your Brain (currently on sale!). It was fun – check it out here.
Update, Saturday: here’s just the part of the program on lead and crime.