James Heckman is one of the nation’s top economists studying human development. Thirteen years ago, he shared the Nobel for economics. In February, he stood before the annual meeting of the Nebraska Chamber of Commerce and Industry, showed the assembled business executives a chart, and demolished the United States’ entire approach to education.

The chart showed the results of cognitive tests that were first performed in the 1980s on several hundred low-birthweight 3-year-olds, who were then retested at ages 5, 8 and 18.

Children of mothers who had graduated from college scored much higher at age 3 than those whose mothers had dropped out of high school, proof of the advantage for young children of living in rich, stimulating environments.

More surprising is that the difference in cognitive performance was just as big at age 18 as it had been at age 3.