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Comment by ignostic | Hacker News Reader

It's been suggested that the removal of lead from fuels, paints, etc. may explain the fact that our IQs have risen since about the same time, and since leveled off somewhat.

http://en.wikipedia.org/wiki/Flynn_effect

Say what you will about environment, but the lead explanation seems to match historical data in all the ways we'd expect it to. Find something that lead does, and we find a trend showing its decline since we started eliminating lead.

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I wonder how this interacts with IQ differences by ethnicity, given that historically some ethnic groups tended to live in inner cities where lead exposure would have been significantly greater.

This has been studied. Gains from the Flynn effect don't show a relationship to race effects in IQ.

Speaking of historical data: leaded plumbing is linked to the decline of the Roman Empire.

Are there reliable sources on that?

Also, using Lead Acetate[1] as an artificial sweetener probably didn't help matters.

[1] https://en.wikipedia.org/wiki/Lead%28II%29_acetate#Sweetener

Here's a good place to get started: http://penelope.uchicago.edu/~grout/encyclopaedia_romana/win...

although this argues that lead in plumbing was NOT a major source of poisoning.

[citation needed]

This is debunked here: http://www.reddit.com/r/AskHistorians/comments/23o92d/on_cos...

Reading the Wikipedia article seems to indicate that most of the rises in IQ due to the Flynn effect happened during the period when fuel lead levels were high.

Would they have risen faster without lead?

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