I find it rather appalling that Mr. Harford would suggest what is effectively a tax on parents of boys for the privilege of allowing them to attend school with girls. This of course would mean only rich brats get to attend gender-integrated school, while the rest of the populace attends at boys-only institutions, the kind of places that tend to bully and scar certain of their numbers for life, and leave the rest even less able to socialize with women than they otherwise would. Why discriminate against boys institutionally? Don't they have enough problems? Their suicide rates are triple that of girls, their achievement less, and on and on.

That said, I agree with Mr. Harford that there aren't enough girls, even in the Western World where, by and large, we don't selectively abort their pregnancies, so let me make my own appalling suggestion. Ban helmets and other measures that reduce the attrition rate of boys that nature clearly intended when we evolved to give birth to boys almost 51% of the time. The boy who swallows too many marbles or skateboards in traffic doesn't get to grow up to have boys of his own. A little passive eugenics will go a long way to restoring the balance that civilized society craves.