3 ms·

Yeah, it just feels like the entire article is too convenient. 1) Everything seems to work out perfectly, no matter how it is considered. For instance, if lea

by colomon 14y ago

Yeah, it just feels like the entire article is too convenient. 1) Everything seems to work out perfectly, no matter how it is considered. For instance, if lead contamination in the ground is such a big deal, why does lead in gas track so closely to the crime rate? Wouldn't it be the case that it would track on the upside but not the downside? 2) He keeps on emphasizing lead lowers IQ. But the Flynn Effect suggests that IQ started going up in the 1930s and has only (maybe) started to level off very recently. It's the exact opposite of what you'd expect based on lead exposure from leaded gas. 3) Long term crime rates have been mostly going down for centuries: http://marginalrevolution.com/marginalrevolution/2011/06/long-term-trend-in-homicide-rates.html http://marginalrevolution.com/marginalrevolution/2011/06/lon... Mind you, I'm fully in agreement that lead sucks and I sure as hell don't want my kid exposed to it. It's just that I'm far from convinced that the crime rates change mostly because of lead exposure. It seems far too tidy an explanation.

jkimmel 14y ago
As far as the Flynn effect is concerned, it's possible that the benefits of general increases in public health (to which the Flynn effect is oft attributed, though somewhat more controversially in recent years) negated the effects of lead on a large scale. However, this does not mean that the Flynn effect would not have had a greater observable magnitude had lead exposure not been so high. Part of me agrees with your overall conclusion about the corollary nature of the research as a whole, but those are my two cents on that particular point.
- colomon 14y ago
  Sure, it's possible (even probable!) there are any number of things affecting IQ. I'm just pointing out that if you'd plotted raw IQ levels versus time, the graph would have the opposite sign from what you'd expect from Drum's lead hypothesis. There may be an explanation that makes it all fit together, but it somehow needs to be addressed, not just ignored or hand-waved away.
tlb 14y ago
You're assuming that the causation goes lead -> lower IQ -> more crime. Indeed, the Flynn effect doesn't support the lower IQ -> more crime relationship. Lead has a wider range of neurological effects than just reducing IQ. The causation may be more likely: lead -> unknown neurological changes -> more criminality & lower IQ.
hydian 14y ago
Good points...just possibilities: 1) Maybe lead in the ground has the same general level of danger as lead paint? Other sources of lead were covered in the article. 2) It is possible (probable even) that the levels of lead have been retarding the growth of IQ, but not reversing it. 3) Ignoring that even your link mentions that the data is skewed due to higher survivability as medical technology has gotten better, this is a separate trend on a separate scale and not really all that relevant. It could possibly be explained by lead from other sources (plumbing maybe?) or other factors outside of the scope of this particular study. If anything, your link reinforces that there was an issue as the homicide rates climbed sharply before suddenly dropping off again.

by colomon 14y ago

jkimmel 14y ago

As far as the Flynn effect is concerned, it's possible that the benefits of general increases in public health (to which the Flynn effect is oft attributed, though somewhat more controversially in recent years) negated the effects of lead on a large scale. However, this does not mean that the Flynn effect would not have had a greater observable magnitude had lead exposure not been so high. Part of me agrees with your overall conclusion about the corollary nature of the research as a whole, but those are my two cents on that particular point.

colomon 14y ago
Sure, it's possible (even probable!) there are any number of things affecting IQ. I'm just pointing out that if you'd plotted raw IQ levels versus time, the graph would have the opposite sign from what you'd expect from Drum's lead hypothesis. There may be an explanation that makes it all fit together, but it somehow needs to be addressed, not just ignored or hand-waved away.

tlb 14y ago

You're assuming that the causation goes lead -> lower IQ -> more crime. Indeed, the Flynn effect doesn't support the lower IQ -> more crime relationship. Lead has a wider range of neurological effects than just reducing IQ. The causation may be more likely: lead -> unknown neurological changes -> more criminality & lower IQ.

hydian 14y ago

Good points...just possibilities: 1) Maybe lead in the ground has the same general level of danger as lead paint? Other sources of lead were covered in the article. 2) It is possible (probable even) that the levels of lead have been retarding the growth of IQ, but not reversing it. 3) Ignoring that even your link mentions that the data is skewed due to higher survivability as medical technology has gotten better, this is a separate trend on a separate scale and not really all that relevant. It could possibly be explained by lead from other sources (plumbing maybe?) or other factors outside of the scope of this particular study. If anything, your link reinforces that there was an issue as the homicide rates climbed sharply before suddenly dropping off again.