When looking at correlating factors, they should also include diet. I remember reading that some Central Asian countries, as recently as a decade ago, were losing more than 5 IQ points on average just to iodine deficiency.
Another HN participant told me about a reply to this latest paper by these authors.<p><a href="http://blogs.discovermagazine.com/notrocketscience/2010/06/29/does-national-iq-depend-on-parasite-infections-er/" rel="nofollow">http://blogs.discovermagazine.com/notrocketscience/2010/06/2...</a><p>When I see gee-whiz news reports about science, even in very reputable publications like The Economist, I think to turn to Peter Norvig's article "Warning Signs in Experimental Design and Interpretation"<p><a href="http://norvig.com/experiment-design.html" rel="nofollow">http://norvig.com/experiment-design.html</a><p>to evaluate the research.
The first thing I thought of is that if lack of diseases is what has been causing the rise in intelligence, then there's likely to be a ceiling that average intelligence will hit as countries become healthier, rather than some mysterious force continually increasing average intelligence forever. That makes me a little sad.
I'm really curious as to how exactly they accounted for other factors. They say they compared findings to other studies that looked at other possible explanations, but quite many of them are certainly correlated if not caused by one another.
It's politically illegal to say that on average whites are smarter than blacks so instead they have this little gem:<p>"....distance from humanity’s African homeland (novel environments could encourage greater intelligence)...."