The national mean IQ score in Japan has jumped more than seven points in a single generation, placing young Japanese more than 10 points higher than their counterparts in the United States and Europe, according to a new study reported in the British scientific journal Nature. Young Japanese now have a mean score of 111 on the American Wechsler scale, compared to 100 for American and European children.

The sharp increase means that more than 10 percent of the Japanese population has IQs above 130--the level found among the most successful professionals. In other developed countries, including the United States, only 2 percent of the population have IQs above 130.

"Since intelligence is a determinant of economic success, as it is of success in many other fields, the Japanese IQ advantage may have been a significant factor in Japan's outstandingly high rate of economic growth," Richard Lynn, a psychologist at New University of Ulster in Northern Ireland, wrote in his report in the May 20 issue of Nature.

In an editorial, Alun Anderson of Nature wrote, "If, indeed, any link between IQ and intellectual achievement is accepted, then the future implication for societies which are becoming increasingly dependent upon technological innovation may be profound."

But Anderson's editorial cautions: "Whether the difference in IQ represents a real difference in 'intelligence' or simply implies that the Japanese are better at IQ tests, remains open to question."

Now 77 percent of Japanese children have a higher IQ than the average American or European, Lynn said. The increase shows up in 6-year-olds, so it may not be a result of superior schooling, Lynn said. "The explanation probably lies largely in environmental improvements" such as health and nutrition.

Among the many factors that might have contributed, Lynn listed a massive movement of peasants to the cities, modernization of health care, and much-improved nutrition, which also has increased the average height by more than two inches in only 20 years.

In four decades, life expectancy in Japan has risen by more than 30 years, to an average span of more than 73 years.