In a study appearing in the Feb. 16 Early Edition of the Proceedings of the National Academy of Sciences, Harvard researchers demonstrated that simple changes in beak length and depth can explain ...

In fact, in some places, like Tunisia, girls showed more variation than boys. If greater variation in math abilities were biologically innate, then it would have shown up everywhere.

Interestingly, the report finds that income differences account for only 30 percent of the variation in mathematics performance between countries, and 21 percent of variation overall.