(CNN) Research has shown that boys and girls' math abilities are about the same at a young age, yet the math field is dominated by men.

The numbers didn't seem to add up.

But a study published Monday in the Proceedings of National Academy of Sciences of the United States of America (PNAS) posits a new explanation for the gender gap in math: Girls are so much better at reading than their male counterparts that they decide to chase humanities-focused professions instead.

The authors looked at reading and math performance data from 300,000 15-year-old students in 64 countries. When they compared the genders' performances, they found a "very large" difference between boys and girls' verbal scores.

Girls, who demonstrated higher marks in reading than boys, are aware that they hold "comparative advantage" when making key decisions about their education and career prospects, the study said. That "can explain up to 80% of the gender gap in intentions to pursue math-studies and career," the authors wrote.

Read More