Average IQ by Country
Is it useful to measure intelligence and report the results
by geographical area? Do we need to know what the average IQ
scores are by country of residence? Will this kind of scientific
exploration lead to biases or outright bigotry against people
who happen to be from particular areas of the world?
The research has been done, and it is interesting. Some readers
might recall previous studies that suggested IQ scores were higher
in northern areas. In that case we may wonder about the possibility
of bias given the fact that virtually all the tests of intelligence
have been developed in countries north of the tropics. But recently
there has been more research that's focused on why intelligence
levels vary from place to place.
For example, a recent article by Christopher Eppig in Scientific
American suggests that the differences could be due to the
higher disease rates in some countries or areas of the world.
Before our work, several scientists had offered explanations
for the global pattern of IQ. Nigel Barber argued that variation
in IQ is due primarily to differences in education. Donald Templer
and Hiroko Arikawa argued that colder climates are difficult
to live in, such that evolution favors higher IQ in those areas.
Satoshi Kanazawa suggested that evolution favors higher IQ in
areas that are farther from the evolutionary origin of humans:
sub-Saharan Africa. Evolution, the hypothesis goes, equipped
us to survive in our ancestral home without thinking about it
too hard. As we migrated away, though, the environment became
more challenging, requiring the evolution of higher intelligence
We tested all these ideas. In our 2010 study, we not only
found a very strong relationship between levels of infectious
disease and IQ, but controlling for the effects of education,
national wealth, temperature, and distance from sub-Saharan Africa,
infectious disease emerged as the best predictor of the bunch.
A recent study by Christopher Hassall and Thomas Sherratt repeated
our analysis using more sophisticated statistical methods, and
concluded that infectious disease may be the only really important
predictor of average national IQ.
Many critics have pointed out that intelligence is not an
easy thing to measure, and the tests which hope to measure it
are often biased in subtle ways.
My own feelings about this are mixed. It seems that some of
the criticism comes from our discomfort with labeling groups
of people as more or less intelligent. But while it is true that
intelligence is difficult to measure, this does not suggest that
the concept itself is invalid, and if we can say without discomfort
that people in this or that area are taller or heavier statistically,
it seems that we might ascribe a statistical difference to intelligence
based on region as well. A statistical difference does not, after
all, mean that every person in a given area is above average
or below average, nor is a lower score in any human capacity
(physical or mental) necessarily indicative of a lower value
as a human being.
Yes, there is a danger in the fact that people do not understand
statistics, and so when attributes are measured statistically
for a group, it is common for some to apply those statistical
measures to every member of that group (and this can be conscious
or exhibited as an unconscious bias). This recent research points
to intelligence being environmentally influenced rather than
a consequence of genetics, perhaps making it less offensive.
But there is a danger in engaging in "politically correct"
science in any case. What we are afraid to investigate we inevitably
must know less about.
It seems to me that it's best to discover what is true even
when that truth is uncomfortable. In this case, for example,
Eppig suggests that "reducing exposure to disease should
increase IQ." That's something worth knowing, isn't it?