Harvesting Intelligence: IQ gains may reach rural Kenya’s kids

Over a recent 14-year stretch, the children of African farmers working in a mountainous region of Kenya appear to have cultivated a record crop of IQ points. These youngsters, ages 6 to 8, scored about 11 points higher in 1998 than their peers did in 1984, a new study finds.

This is the fastest increase in a population’s average IQ ever reported, say psychologist Tamara C. Daley of the University of California, Los Angeles and her colleagues.

During the 20th century, average IQ in 20 industrialized nations rose 18 points in each 30-year generation. This phenomenon, first noted in 1987 by political scientist James R. Flynn of the University of Otago in Dunedin, New Zealand, is now called the Flynn effect.

At their current rate of increase, the Kenyan children would be expected to display a 24-point gain over 30 years, Daley’s group reports in the May Psychological Science.

“To our knowledge, this is the first study to document the Flynn effect in a rural area of a developing country,” Daley says.

The researchers administered three tests commonly used in IQ assessments to 118 children in 1984 and 537 children in 1998. In a problem-solving test, kids selected an appropriate missing pattern that would make sense in a given series of patterns.

A verbal test required children to examine four pictures and point to the one named by the tester. Finally, children flexed their memories by trying to repeat number lists of varying lengths spoken by the tester.

Scores on each of these tests increased markedly from 1984 to 1998. As in industrialized nations, the largest IQ jump occurred on the problem-solving test.

Several environmental factors influenced this trend, the scientists theorize. First, greater parental emphasis on schooling in 1998 reflected expanding literacy among adults. Nutrition and health may also have contributed to the rural Flynn effect. Increased protein consumption has helped boost the children’s energy levels and alertness, the researchers contend. At the same time, childhood anemia, which interferes with thinking skills, has declined in frequency.

Flynn calls the new study a “highly significant” look at how IQ rises during the early stages of modernization. The Kenya case corresponds to IQ increases in England and the United States in the first half of the 20th century, after the industrial revolution fostered better nutrition and widespread secondary-school education, Flynn says.

After 1950, in his view, IQ-promoting factors included reduced family sizes, more leisure activities, and an emphasis on jobs demanding abstract thinking.

In contrast, sociologist Linda Gottfredson of the University of Delaware in Newark questions whether the Kenya findings demonstrate a Flynn effect. Daley’s group may have studied an especially advantaged group of children in 1998 compared with the 1984 sample, she notes. U.S. black children from the most advantaged families compared with those without such advantage show an IQ difference of about the same amount as the two groups of Kenyan children displayed.

“There’s a real Flynn effect in industrialized nations, but its cause is a great mystery,” Gottfredson remarks.


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Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeology and mental health issues.