The Consequence of Unnatural Selection: 160 Million Missing Girls

As best as demographers can figure, the world is short about 160 million girls and women–equivalent to the entire female population of the United States. With numbers of this magnitude in the news from time to time, many people are aware that sex selection is a matter of concern. But most Americans with whom I’ve discussed it consider sex selection somewhat abstract, and certainly faraway and fading–a practice confined to India and China, prevalent among poor people stuck in the sway of ancient traditions. The solution, they tend to assume, lies in economic development and advances in gender equality. In this view, son preference and sex selection, like the so-called population bomb of the 1960s and 1970s, will diminish more or less on their own, as a corollary of modernization and improvements in the status of women.

In the new book Unnatural Selection: Choosing Boys over Girls, and the Consequences of a World Full of Men, out this week, Beijing-based journalist Mara Hvistendahl shows these assumptions to be seriously mistaken. Selecting for sons is growing not just in South...