How Adding Iodine to Salt Boosted Americans’ IQ

Aluminum reacts with iodine. The reaction produces a lot of heat so that the iodine sublimates and produces the characteristic violet vapor.

I vaguely remember hearing about how iodine was good for you when I was a kid. It impressed me enough that I still buy iodized salt. I didn't know that it had any effect on intelligence until Iaman sent me a link.

How Adding Iodine to Salt Boosted Americans’ IQ

I've seen several maps recently that show that people from temperate zones are more intelligent than people from the tropics. I wonder if iodine is a factor.