Kevin Drum beats his, er, drum a little bit on his favorite topic – leaded gasoline:
… Britain’s violent crime rate peaked about 15 years after it did in the US. Second, it dropped a lot faster than it did in the US. Why?
Because, first, Britain adopted unleaded gasoline about 13 years after the US (1988 vs. 1975). And second, because it phased out leaded gasoline a lot faster than the US. Within four years Britain had cut lead emissions by two-thirds, which means there was a very sharp break between infants born in high-lead and low-lead environments. Likewise, this means there was a sharp break between 18-year-olds with and without brain damage. In 2006, nearly all 18-year-olds had grown up with lead poisoned brains. By 2010, that had dropped substantially, which accounts for the stunning 40 percent drop in violent crime in such a short time.1
This is one of the reasons the lead-crime hypothesis is so persuasive. Not only does recorded crime fit the predictions of the theory—both in timing and slope—but it does so in many different countries. What other theory would predict a gradual drop in violent crime between 1991-2010 in the US and a sharp decline in violent crime between 2006-10 in Britain? Especially considering that the US and Britain have entirely different policing, poverty rates, race issues, etc.?
Is there a similar hypothesis with regard to lead paint?
This is a bit new to me, so I decided to look at a similar cause-effect argument for the drop in the crime rate, this regarding a drop in the 1990s – the abortion legalization argument of Steven Levitt (of Freakonomics fame). Basically, he correlates the legalization of abortion in certain states and countries with a drop in the crime rate 20 years later – when the aborted fetuses would have begun committing the crimes which were not committed. A defense of this hypothesis by Levitt in 2005 is here.
But this has not gone undisputed. Besides the hate mail Steven and his co-writer, Stephen Dubner received1, there’s also been scholarly argument (good!). Psychologist Steven2 Pinker has attacked the hypothesis and favored a crack cocaine hypothesis, instead. From an undated post (perhaps 2013) on the Uncertainty Blog, which I copy mostly for my own benefit, is a quote from Pinker’s book, The Better Angels of Our Nature:
To begin with, the freakonomics theory assumes that women were just as likely to have conceived unwanted children before and after 1973, and that the only difference was whether the children were born. But once abortion was legalized, couples may have treated it as a backup method of birth control and may have engaged in more unprotected sex. If the women conceived more unwanted children in the first place, the option of aborting more of them could leave the proportion of unwanted children the same. In fact, the proportion of unwanted children could even have increased if women were emboldened by the abortion option to have more unprotected sex in the heat of the moment, but then procrastinated or had second thoughts once they were pregnant. That may help explain why in the years since 1973 the proportion of children born to women in the most vulnerable categories – poor, single, teenage, and African American – did not decrease, as the freakonomics theory would predict. It increased, and by a lot.
I wonder what women – especially mothers – think of that criticism.
Mostly, the point I’m making is that the leaded gasoline hypothesis is interesting – even fascinating – but at best I suspect it’s just one in a suite of causes, some Nurture, some Nature. I don’t think this hypothesis is a settled question just yet. In fact, in my mind it raises questions of a more basic nature – that is, if our minds were totally undamaged by the environment (and our families), would we be more or less likely to engage in anti-social behaviors? (This is an appeal to the old philosophical position that we were perfect, even angelic, before we were stained by “progress” – advanced by Jean-Jacques Rousseau. I find it dubious myself.)
Heck, get right down to it: what constitutes “not damaged”? Can this be defined without reference to social agendas? Can it be defined in terms of evolutionary biology? Is there a completely objective definition / framework?
