From Foreign Policy (link):
The lost boys of Prof. Albert Macovski are upon us. Twenty years ago, the ultrasound scanning machine came into widespread use in Asia. The invention of Macovski, a Stanford University researcher, the device quickly gave pregnant women a cheap and readily available means to determine the sex of their unborn children. The results, by the million, are now coming to maturity in Bangladesh, China, India, and Taiwan. By choosing to give birth to males”and to abort females”millions of Asian parents have propelled the region into an extraordinary experiment in the social effects of gender imbalance.
…Understanding the effect of the testosterone overload may be most important in China, the rising Asian superpower. Prompted by expert warnings, the Chinese authorities are already groping for answers. In 2004, President Hu Jintao asked 250 of the country’s senior demographers to study whether the country’s one-child policy”which sharply accentuates the preference for males”should be revised. Beijing expects that it may have as many as 40 million frustrated bachelors by 2020. The regime, always nervous about social control, fears that they might generate social and political instability.
Brigham Young University political scientist Valerie Hudson”the leading scholar on the phenomenon of male overpopulation in Asia”sees historical evidence for these concerns.