The Law of Unintended Consequences


There’s a natural ratio of men to women for our species, and it is not equal. For every 100 girls, 105 boys are born. But in some places, like India and China, the ratio is skewed. One Chinese city recorded an astounding 163 boys born per 100 girls. So, why is this happening?

The ultrasound.

The expanding use of this technology has allowed expecting parents to abort unwanted girls and keep the boys. The ability to sex-select has caused the disappearance of an estimated 160 million girls in Asia alone.

In this Marketplace segment, Stephen J. Dubner reports on the unintended consequences that come with new technology. You’ll hear from Mara Hvistendahl, the author of Unnatural Selection: Choosing Boys Over Girls, and the Consequences of a World Full of MenStephen Quake, a biophysicist at Stanford, and Freakonomics co-author and University of Chicago economist Steve Levitt.

Here’s where to find Marketplace on the radio near you.

Preemptive Placebo

While it may have been an unintended consequence for the manufacturer, it may be not so unintended for the governments involved.

A skewed ratio of women to men may be the perfect stealth population control technique in countries with deep suspicions of - or outright hostility toward - population politics.

Statisticians measure reproductive rates in terms of live-births-per-female. Fewer females means fewer live births.

In male dominated South Asia, more men mean more workers.

Pietr Hitzig


I was about to make my maiden letter to this fine blog but was wise enough to review the comments made. You made my argument.


You should look at what R.A. Fisher had to say about the sex ratio.

Preemptive Placebo

In both fruit flies and humans Fisher's Principle will adjust the skewed ratio in a few generations.

Unlike fruit flies, human have societal repercussions that could potentially costly more - during the time it takes for the ratio to regress to the mean - than the benefit of a decrease in population in an already overpopulated region.


So means that roughly a quarter of the male population has zero chance of getting married. I really wonder how that will affect social stability.


Two consequences of having a lot more men than available women:

Increased homosexuality, which is officially taboo in China. Is it possible that a large number of militant homosexuals might lead societal change?

A bunch of angry, frustrated young men, many of whom would be enlisted in the world's largest standing army. What are the chances of some untoward event, like a missile fired off by some young hothead, initiating a war? If I lived in Taiwan, I would be worried.

Eric M. Jones

KevinB: "... consequences of having a lot more men than available women: Increased homosexuality..."

Oh really? This will surprise a lot of gay guys. And an excess of women?...more lesbians?


Where is the OUTRAGE?? I'm pretty sure you've repeatedly said "160 million". I'll ask once more ... where is the moral outrage???

Enter your name

More interesting to me:

Where is the outrage that deliberate sex selection through abortion is legal in the USA? We condemn it as barbaric in India (where it is illegal) and China, but it appears that there are no laws banning it here at home, and it is done.

Jasper Janssen

One wonders if multiplemarriages (of the more than one male variety), licit or illicit, might become more common.

I'd say it's either that or good old fashioned trench warfare.

busy b

Violence would certainly be higher per capita in a more male society.


Possibly also a problem in the UK. See

Mike B

This might be a long term positive for Women's rights. As women become scarcer they should become more valuable and reverse the centuries old traditions of being seen as burdens (due to dowry costs, leaving the household, etc). If having a girl means she can win substantial compensation for her family in a marriage then the supply of girls should naturally increase, only this time with increased respect.


There is also a paper saying it's better for poor families to have girls because they can marry up a rich man. In skewed sex ratios, the worst off are poor men because no one wants to marry them.


In order to try and prevent femal infanticide, India has made it illegal to find out the sex of a child prior to birth. The doctor/ultrasound tech is prohibited from revealing the sex of the child to the parents. Passing a law and stopping the practice are however two completely different things.


There will be unintended consequences of the unintended consequences.

I wonder what will happen when ultrasound technology advances to the place where we can determine whether an unborn child will have dimples or not? or the color of the baby's eyes? or their odds of making a perfect score on the SAT?

You cannot toss away millions of unborn girls like you are choosing between pairs of shoes, yet not somehow, someway, eventually feel the pent up anger of God or the universe for treating human babies with less regard than we treat Great White Sharks.

Men have supposedly went to war for women. One day it might be more literal than we imagined. Of course, the good news is that the war will thin out the male numbers...then we can start over.

This is not about pro-choice vs. pro-life. You can be pro-choice and still realize that to treat unborn children like choosing between supermarket meat items is somehow wrong.



Umm. Don't forget infanticide.