(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.
Other factors contribute to the gender gap
The study doesn't claim to entirely explain the gender gap in the math field.
Girls also internalize social cues and stereotypes about who is good at math and science from a young age, says Erin Hogeboom of the National Girls Collaborative Project, which works to encourage girls to pursue science, technology, engineering and mathematics (STEM) careers.
"It can be as subtle as educators asking a question in a STEM course and unintentionally calling on boys more than girls," Hogeboom says.
She added, "In mass media, we don't see a lot of women being championed and celebrated for their STEM achievements."
And even when women do decide to pursue jobs in the STEM field, they say they experience gender discrimination, a January 2018 Pew survey found.