LATEST BLOG
Sunday, April 13, 2014
Tuesday, April 08, 2014
Sunday, April 06, 2014
Welcome to Matt Ridley's Blog
Matt Ridley is the author of provocative books on evolution, genetics and society. His books have sold over a million copies, been translated into thirty languages, and have won several awards.

Please note that this blog no longer accepts comments (there was too much spam coming in!). If you're reading this blog and want to respond then please use the contact form on the site.

You can also follow me on twitter.

The distorting of the human sex ratio

My latest Mind and Matter column in the Wall Street Journal:

Even a rational optimist is pessimistic about some things. Here's one: the gradual distortion of the human sex ratio by sex-selective abortion. A new essay by the demographer Nicholas Eberstadt concludes that "the practice has become so ruthlessly routine in many contemporary societies that it has impacted their very population structures." He finds "ample room for cautious pessimism" in the fact that this phenomenon is still very much on the increase.


For obscure reasons, the human sex ratio is always slightly male-biased, but in the natural state it rarely goes above 105 male births per 100 female ones, except in small samples. In China's last mini-census in 2005, the ratio was nearly 120 to 100 and in some districts over 150. That this is caused by sex-selective abortion (and not, for example, by a hepatitis-B epidemic, which can favor male births) is proved by a ratio of 107 to 100 among first-born children but nearer 150 among ones born later.


China is not the only country where this is happening. By the early 21st century, all four Asian "tigers"-South Korea, Singapore, Hong Kong and Taiwan-had a "naturally impossible" ratio of 108 or higher. India has an increasing ratio, as high as 120 in some states. Even some European and central Asian countries (including Albania, Georgia and even Italy) have unnaturally male-biased births. Nearly half the world falls in this category.


For 2005 to 2010, the United Nations puts the world sex ratio at birth at 107 boys to 100 girls. Assuming 105 is natural, Dr. Eberstadt calculates that this translates into a global "girl deficit" of at least 32 million. The consequences, in terms of unmarried and perhaps disruptive men, may be serious and long-lasting.
The phenomenon apparently gets worse with prosperity. Countries like Vietnam have shown male-biased birth ratios only since starting to grow rapidly richer. An analysis by Christophe Guilmoto and Sébastien Oliveau has shown that, in China and India, the problem is more acute in fairly rich regions.


Why? As people get richer, they plan smaller families, and those who have had a girl first are prepared to go to great lengths to ensure having a boy the next time. Economic growth also means more access to ultrasound scanning and abortion. Female infanticide after birth still happens, but it is both psychologically harder than abortion and less easy to disguise as a medical necessity.


Of course, near-perfect sex selection can be achieved with in-vitro fertilization (by implanting only male embryos), but this will remain a luxury of the very rich. What about sperm selection? A clinical trial getting under way in the U.S. will test a method for sorting human sperm into X (female determining) and Y (male) types; it's already used in animals such as dairy cattle with 93% accuracy. If this method becomes cheap, it's easy to imagine clinics offering it in China and India.


Policy seems largely powerless to fight this problem. Sex-selective abortion is illegal in virtually all countries. China's authoritarian "one-child policy" is in marked contrast with India's more laissez-faire attitude to family planning, yet both have produced widespread killing of female fetuses.


All of this presupposes a continuing general preference for boys in such societies, something that should eventually wane as their economies develop more equal employment opportunities. Given the way in which technology is evolving to make sex selection easier, perhaps the only short-term hope is to shame people. South Korea's sex ratio at birth reached 115 to 100 in the 1990s but has since fallen back to 107, thanks to what Mr. Eberstadt calls a "spontaneous and largely uncoordinated congealing of a mass movement for honoring, protecting and prizing daughters."