This week I will be blogging Mara Hvistendahl's Unnatural Selection: Choosing Boys Over Girls, and the Consequences of a World Full of Men.
The biggest danger of masses of men who will never marry is that they will be violent and commit crimes. It is possible they will be used for war, but that is not so predictable from the sheer demographic facts.
The best news is that Hvistendahl thinks the massive sex imbalance is a temporary stage in a country's economic development. As evidence she cites the fact that in 2007, South Korea had a natural sex ratio for the first time in twenty years. It is the first country to start to come back from a massive sex imbalance. They still have super low fertility - 1.22 children per woman - but South Korea seems to have turned a corner in both its sex ratio and its overall fertility. This gives hope that the other massively imbalanced countries can begin to walk back from the precipice.