http://blogs.discovermagazine.com/notrocketscience/2010/06/2...
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"
http://norvig.com/experiment-design.html
to evaluate the research.
http://blogs.discovermagazine.com/notrocketscience/2010/06/2...
So why is the point of having a research about causation when various independent causes can exist and do not test how much the hypothetical cause affects the causation relationship in general? Should I publish a paper on intelligence and ice cream consumption by population in the last 50 years to show how ridiculous the entire situation is?
Sounds like that sort of paper that someone publishes only so that his name get cited more times.
"....distance from humanity’s African homeland (novel environments could encourage greater intelligence)...."
Note that one of the things they did not control for was race.
It's racist to say this, I know, and more importantly it's not nice. But if you are going to make a study, you have to deal with reality.
Control for race, and then check the correlation with parasites.
PS: Medical outcomes are far more dependent on the average level of care than the peek level of care. EX: There is a lot of evidence that the average doctor is significantly more effective than a "high preforming" doctor that is sleep deprived.
The correlation is about 67%, and the chance that it might have come about at random is less than one in 10,000. But correlation is not causation, so Mr Eppig and his colleagues tried to eliminate other possible explanations. Previous work has offered income, education, low levels of agricultural labour (which is replaced by more mentally stimulating jobs), climate (the challenge of surviving cold weather might provoke the evolution of intelligence) and even distance from humanity’s African homeland (novel environments could encourage greater intelligence) as explanations for national differences in IQ. However, all of these, except perhaps the last, are also likely to be linked to disease and, by careful statistical analysis, Mr Eppig and his colleagues show that all of them either disappear or are reduced to a small effect when the consequences of disease are taken into account.
There is, moreover, direct evidence that infections and parasites affect cognition. Intestinal worms have been shown to do so on many occasions. Malaria, too, is bad for the brain. A study of children in Kenya who survived the cerebral version of the disease suggests that an eighth of them suffer long-term cognitive damage. In the view of Mr Eppig and his colleagues, however, it is the various bugs that cause diarrhoea which are the biggest threat. Diarrhoea strikes children hard. It accounts for a sixth of infant deaths, and even in those it does not kill it prevents the absorption of food at a time when the brain is growing and developing rapidly.
