CNN Throughout history, a surplus of young men often heralded violence. The American frontier earned its "Wild West" reputation for lawlessness because its towns overflowed with men, yet marriageable women were vanishingly rare. In The Chivalrous Society, historian Georges Duby argued that European expansionism, from the Crusades to colonialism, was fueled by a surplus of ambitious and aggressive young men with otherwise poor reproductive prospects.
China is already feeling the effects of so many bare branches. The economist Lena Edlund estimates that every one percent increase in the sex ratio results in a six percent increase in the rates of violent and property crime. In addition, the parts of China with the most male-biased sex ratios are experiencing a variety of other maladies, all tied to the presence of too many young men. Gambling, alcohol and drug abuse, kidnapping and trafficking of women are rising steeply in China.
The bare branch problem will be compounded as income inequality rises. China's Gini coefficient of income inequality has risen from less than 0.3, 25 years ago, to almost 0.5 today. On the Gini scale, 0 represents perfect equality while a score of 1 represents complete inequality.
It would be difficult to overstate the urgent need for China to emulate South Korea in eliminating sex-biased abortion and neglect.
But just as urgently, China needs creative large-scale solutions to the problems that unprecedented cohorts of bare branches will cause as they come of age over the next two decades. Those millions of disaffected young men will not only present a danger to themselves, but those living alongside them. And, as Hudson and den Boer have been arguing for some time, the bare branches will also make perfect fodder for political agitation, fundamentalism and possibly terrorism.