New Zealanders have helped prove new research showing women are smarter than men.
Since IQ testing began a century ago, women have been as much as five points behind, leading psychologists to suggest embedded genetic differences.
But that gap has been narrowing in recent years and this year, women have moved ahead, according to James Flynn, a world-renowned authority on IQ tests.
"In the last 100 years the IQ scores of both men and women have risen but women's have risen faster," said Mr Flynn.
"This is a consequence of modernity. The complexity of the modern world is making our brains adapt and raising our IQ."
Flynn's research collated IQ examination results from New Zealand, Australia, the United States, Canada, Argentina, Estonia and countries in western Europe.
In New Zealand, Estonia and Argentina, women scored marginally more than men.
However, in Australia the results were almost identical for both sexes.
One possible explanation is that women's lives have become more demanding as they multitask between raising a family and doing a job, Flynn said.
Another is that women have a slightly higher potential intelligence than men and are only now realising it.
Mr Flynn, who will publish his findings in a book, said more data was needed to explain the trend.
"The full effect of modernity on women is only just emerging," he added.
The data for making exact comparisons between countries was sparse.
Mr Flynn said: "As the world gets more complex, and living in it demands more abstract thought, so people are adapting."
He added: "I suspect that the same trends are happening in Britain, too, although the data is too sparse to be sure."