NIcholas Kristof wrote this in May, 2014.
“So why does girls’ education matter so much? First, because it changes demography.
One of the factors that correlates most strongly to instability is a youth bulge in a population. The more unemployed young men ages 15 to 24, the more upheaval.
One study found that for every 1 percentage point increase in the share of the population aged 15 to 24, the risk of civil war increases by 4 percent.
That means that curbing birthrates tends to lead to stability, and that’s where educating girls comes in. You educate a boy, and he’ll have fewer children, but it’s a small effect. You educate a girl, and, on average, she will have a significantly smaller family. One robust Nigeria study managed to tease out correlation from causation and found that for each additional year of primary school, a girl has 0.26 fewer children. So if we want to reduce the youth bulge a decade from now, educate girls today.”