If you've worked your way to the top in a university maths, physics or engineering department - you're very unlikely to be a woman.
But why should this be?
In 2005, Harvard University president Larry Summers provoked a storm of protest when he suggested that at least part of the reason for the dearth of women in these fields was biological - in other words, the result of innate differences in tastes and aptitudes between the sexes.
....In 2005/6, while more than half of all UK students in higher education were female, just 3% of maths and 2% of civil engineering professors were women, a recent study revealed.
Professor David Geary, of the University of Missouri in the US, suggests there are two key difference between the sexes that might account for the disparity in numbers.
The first is a difference in spatial abilities - the capacity to visualise things, particularly in three dimensions.
The second is an increased interest in objects and how things work.
According to Professor Geary: "Males are better in both of those areas, and both areas contribute to interest in maths and engineering, and performance in some areas."
....Professor Geary says: "These differences are found very early on in life.
"If you look at interest in toy cars or mechanical objects, boys like those much more from the pre-school years.
"Also, girls who have been exposed to a testosterone-like hormone in the womb show boy-like toy preferences."
....Dr Helena Cronin, who studies evolutionary theory and sex difference at the London School of Economics, argues that past statistics give no indication of what might happen in the future.
She says: "On that basis, women marathon runners, who have been catching up with men since the 1920s, were predicted to overtake men in the 1990s, and presumably would be running beyond the speed of light if it were continued for long enough."
According to Dr Cronin, it's the numbers of men at the extremes of ability that are most telling:
"For males, the difference between the worst and the best is far, far greater.
"This is a very important aspect of male-female differences.
"One way of looking at this is that among males there are more dumbbells, but there are also more Nobels."
....She describes Harvard's reaction to Larry Summers' speech as "shameful", and sees it as an example of science being hijacked by politically-correct ideology.
She says those who are striving for 50/50 sex ratios across the sciences should look at the scientific evidence first.
She says: "If you want to change the world, first you have to understand it."