The age-old battle between the sexes over brainpower may finally have a victor, with a new research revealing that men have a greater general mental ability or G than women.

At each and every level of family income, for every level of fathers' and of mothers' education, and for each and every one of seven ethnic groups, males had higher G scores than females, the study found.

A study of 100,000 17- to 18-year-olds on the Scholastic Assessment Test published in the September 2006 issue of the journal Intelligence, has confirmed a surprising new finding -- that men have a 4- to 5-point IQ advantage over women by adulthood.

Because girls mature faster than boys, the sex difference is masked during the school years, which explains why the sex difference was missed for 100 years.

A study published in the September 2006 issue of the journal Intelligence analyzed 145 items from the Scholastic Assessment Test in 100,000 17- to 18-year-olds and found a male IQ advantage of 3.63 points.

The male-female differences were present at every socioeconomic level, and across several ethnic groups.

The average male advantage was found "throughout the entire distribution of scores, in every level of family income, for every level of fathers' and of mothers' education, and for each and every one of seven ethnic groups," said J. Philippe Rushton, professor of psychology at the University of Western Ontario, one of the authors of the study.

The paper's results dovetail with those from several other recently published studies showing that men, surprisingly, have a 4- to 5- IQ point advantage over women by late adolescence and early adulthood. Before that age the two sexes are equal in general intelligence.

As such, the findings overturn a 100-year consensus that men and women average the same in general mental ability.

Because girls mature faster than boys, the sex difference is masked during the school years.

For decades, however, psychologists have accepted that men and women differ in their test "profiles," with males averaging higher on tests of 'spatial ability' and females higher on tests of 'verbal ability'.

These differences were assumed to average out.