Psychologist Jelte Wicherts at the University of Amsterdam and colleagues trawled through Lynn and Vanhanen's data on Africa. They found once again that few of the recorded tests even attempted to be nationally representative (looking at "Zulus in primary schools near Durban" for example), that the data set excluded a number of studies that pointed to higher average IQs, and that some studies included dated as far back as 1948 and involved as few as 17 people.
Wicherts and his colleagues also point out that there is considerable evidence the tests Lynn and Vanhanen use to make their case "lack validity in test-takers without formal schooling." It is, surely, hard to take a multiple-choice test when you don't know how to read. Not surprisingly, IQ test results in Africa are weakly aligned to other measures of intelligence that don't require written test-taking.
Wicherts also points out international evidence that average IQs can rise dramatically over time -- by as much as 20 points in the Netherlands between 1952 and 1982, for example. In fact, Africa's current estimated "average IQ" is about the same as Britain's in 1948. The phenomenon of rising average IQ scores over time is known as the "Flynn effect," named after political scientist Jim Flynn, who popularized the result. It suggests that factors such as improved nutrition, health care, and schooling may all improve IQ test performance. Of course, Africa is currently behind richer regions on such factors, though it is rapidly catching up. Indeed, the Flynn effect may have added as much as 26 points to estimates of Kenyan IQ over a recent 14-year period. That's more than the gap between reported IQs in Africa and the United States estimated by Wicherts and colleagues based on samples from 1948 to 2006. In short, all of the evidence suggests lower levels of development cause lower test scores -- not the other way around.
Lynn and Vanhanen's work is part of a whole cottage industry of pseudo-scientific examination of race and development. For example, Satoshi Kanazawa at the London School of Economics and co-author of "Why Beautiful People Are More Intelligent," suggests a strong relationship between IQ and life expectancy across countries. On the basis of the quality of his work, Kanazawa isn't about to win a beauty pageant. The idea that better health might lead to improved IQ is a subject Kanazawa dismisses in one paragraph, arguing the "current consensus" is that "general intelligence is largely hereditary." Of course, that consensus -- to the very limited extent it is one -- is based on studies within populations born to mothers who enjoyed health care and good diets. And those people went on to enjoy similar luxuries themselves as well as a quality basic education. In short, they don't look much like people born in Niger in 1960.
There is a simple explanation for why the IQs of the offspring of colonists appear higher than those of the first descendants of the colonized. It's because the colonizers acted much as Thomas Carlyle's writing suggested they would -- as overlords with little or no interest in providing public services like a decent education or health care to a native population viewed with disdain. This left local populations malnourished, in poor health, and ill-educated -- if they were lucky enough to be in school at all.
The good news is that decolonization began a process of leveling the playing field, with rapidly climbing and converging indicators of health and education worldwide. Thanks to the Flynn effect, IQs are doubtless on a path of convergence as well, and the poisonous idiocy of genetic explanations for wealth and poverty will soon lose what little empirical support they might appear to have today.
Note: This will be my last weekly Optimist column for ForeignPolicy.com, though I will keep writing for the print publication on a regular basis. Thanks to Charles Homans and Benjamin Pauker for their excellent and patient editing over the past 18 months, and many thanks to you all for reading and reacting.