In the 1960s, a Caltech geochemist named Clair Patterson made the case that there had been worldwide contamination of living things by lead, due to the lead in gasoline. There were great increases in the amount of lead in fish and human skeletons, for example. More than anyone else he was responsible for the elimination of lead in gasoline. (By coincidence, this was just shown on the new Cosmos TV series.) A professor of pediatrics at the University of Pittsburgh named Herbert Needleman did some of the most important toxicology, linking lead exposure (presumably from paint) and IQ in children. Children with more lead in their teeth had lower IQ scores. The importance of this finding is shown by the fact he was accused of scientific misconduct.
When lead was eliminated from gasoline, blood levels of lead went down — and so did crime. The idea that childhood lead exposure causes crime many years later explains so many otherwise-hard-to-explain facts, especially worldwide declines in crime rates, that I conclude it’s true: lead exposure does cause criminality. Kevin Drum wrote a long article about this in Mother Jones a year ago and followed up his original article in many ways. A BBC radio show yesterday covered the topic.
This interests me for two reasons. One is simple. It shows the value of mercury in my teeth fillings made me stupider. There’s still lots of lead in the world — in old windowpanes, for example. And you are exposed to thousands of other modern chemicals (e.g., in cleaning products) whose effects on your brain are essentially unknown.
The other reason is complicated. It involves the context of this discovery. Mostly, the health research establishment has been unable to get anything right. Heart disease has been the #1 killer for decades; doctors still claim (and vast number of people, including New York Times health writers, believe them) that it is caused by cholesterol. Depression and bipolar disorder might be the single greatest cause of suffering nowadays — and psychiatrists are still claiming it is caused by “chemical imbalance” in the brain. (For my view of what causes depression, see this.) Beyond figuring out that lung cancer is caused by smoking, there has been almost no progress understanding what causes cancer. The “oncogene theory” of cancer turned out to be a dead end. There have been little bits of progress here and there but on the big issues, there has been nonsense decade after decade — and lack of realization that it is nonsense.
In contrast, taking lead out of gasoline was a big step forward in public health and pointing out the link to crime a big step forward in understanding crime. Rare examples of progress. What can I learn from that? I have stressed the importance of insider/outsiders — people close enough to understand but far enough away to have freedom. The lead/crime case supports that. Clair Patterson was a geochemist, not a toxicologist. Rick Nevin, the first person to argue that lead causes crime, was an economist, not a criminologist. Both of them had a good methodological understanding and used this to shed light on a different area than their original training. (Obviously I have used my background in experimental psychology, especially my methodological knowledge — how to experiment, how to measure brain function — to shed light on many health questions.) The lead/crime link also supports my view that the notion that “correlation does not equal causation” does more harm than good. The immediate response of many many people to the lead/crime evidence was exactly that — putting them on what turned out to be the wrong side. Whatever truth correlation does not equal causation might have is outweighed by the damage it does when it is used to ignore evidence. How smart do you have to be to realize “correlation does not equal causation” is stupid? To me don’t ignore evidence is the most important principle of science. But many university professors don’t agree with me.
I’m also impressed — in a good way — by Drum’s article. At least it exists. Anyone can read it and then look further, for example at original scientific articles. I wouldn’t say it was easy to write but it did not require expensive travel, extensive interviews, or months of research. It did require original thinking. In contrast, the New York Times and The New Yorker, which do allow expensive time-consuming journalism, haven’t published anything nearly as good in decades. The New York Times‘s idea of high-quality journalism seems to be a series about the high cost of health care while The New Yorker weighs in on the harm done by Dr. Mehmet Oz.
Thanks to James Keller.