Is human intelligence declining, or are IQs on the rise? A new study conducted by psychologists at King's College London suggests that we're getting smarter, but just how much smarter depends on what part of the world you're talking about.
To conduct the study, published in the March-April 2015 issue of the journal Intelligence, the researchers looked at 64 years of IQ score data for more than 200,000 people living in 48 countries. Overall, they found that global IQ scores have risen by an average of 20 points since 1950.
Notably, the biggest gains were in developing countries such as India and China, where there have been marked improvements in health care and education in recent decades. By contrast, countries like the U.S. showed much smaller increases.
The study was intended to test the so-called Flynn effect, the long-term rise in IQ scores identified in 1982 by James Flynn. The New Zealand political scientist showed that in all countries where data was available, IQ had risen by three to four points each decade since 1930. The increase, Flynn concluded, was largely due to improved living standards.
"The main results of this study have confirmed the Flynn effect that the IQ rise can be observed in many countries and all age groups," said Robin Morris, a co-author of the new study and professor of psychiatry at King's College London. "Also, it further contributes that the Flynn effect is stronger in developing countries."
The Flynn effect has been observed in a number of subsequent studies, although some research has shown just the opposite, such as a 2013 University of Amsterdam study, which found that average IQ in Western countries is actually 14 points lower than it was during the Victorian era. The authors argued that this decline reflected the fact that highly educated women tend to have fewer children.
Still, more research is needed to explain why exactly the Flynn effect seems to be magnified in developing countries.
“This study clearly now confirms the Flynn effect beyond reasonable doubt and the manner in which intellectual test performance is catching up in low income countries," Morris said in a January press release. "The challenge, of course, is to define more clearly why the increases have been taking place.”