The first we’d read of Mara Hvistendahl’s book “Unnatural Selection” — about the consequences, in an age of ultra sound and abortion, of choosing boys over girls — was in a powerful review the other day in the Wall Street Journal. It was written by the Weekly Standard’s Jonathan V. Last, who writes that Ms. Hvistendahl’s tome “might be one of the most consequential books ever written in the campaign against abortion.” Though Ms. Hvistendahl herself seems to be less a foe of abortion than sex selection, her book, Mr. Last writes, “is aimed, like a heat-seeking missile, against the entire intellectual framework of ‘choice.’”

The Journal’s review was followed this week in the New York Times with a brilliant column by its in-house conservative, Ross Douthat, called “160 Million and Counting,” a reference to the number of girls who are “missing” as the ghastly toll of sex selection emerges in such countries as India, China, Korea, and even, to a degree, here in America. The number has soared since 1990 when the New York Review of Books issued Amartya Sen’s essay about sex selection and infanticide called “More Than 100 Million Women Are Missing.”

Mr. Douthat characterizes Ms. Hvistendahl, a journalist by trade, as arguing “that most of the missing females weren’t victims of neglect. They were selected out of existence, by ultrasound technology and second-trimester abortion.” He notes that the “spread of sex-selective abortion is often framed as a simple case of modern science being abused by patriarchal, misogynistic cultures.” He writes: “Patriarchy is certainly part of the story, but as [Ms.] Hvistendahl points out, the reality is more complicated — and more depressing.”

For it turns out that “female empowerment often seems to have led to more sex selection, not less.” He quotes Ms. Hvistendahl as writing that in many communities “women use their increased autonomy to select for sons,” because, Mr. Douthat says, “male offspring bring higher social status.” In India sex selection “began in ‘the urban, well-educated stratum of society,’ before spreading down the income ladder.” But it didn’t happen entirely naturally. It turns out, in Mr. Douthat’s telling, that “Western governments and philanthropic institutions have their fingerprints all over the story of the world’s missing women.”

The culprits include the Rockefeller Foundation and the International Planned Parenthood Foundation, among other do-good organizations, and “an unlikely alliance between Republican cold warriors worried that population growth would fuel the spread of Communism and left-wing scientists and activists who believed that abortion was necessary for both ‘the needs of women’ and ‘the future prosperity — or maybe survival — of mankind,’ as the Planned Parenthood federation’s medical director put it in 1976.”

Mr. Douthat characterizes “Unnatural Selection” as reading “like a great historical detective story … written with the sense of moral urgency that usually accompanies the revelation of some enormous crime. But what kind of crime?” He says the question haunts “the broader debate over the vanished 160 million,” as, we would add, it haunted at least some of the foreign correspondents covering Asia in the years after the post-Vietnam president of the World Bank, Robert McNamara, began lecturing on the dangers of population growth.

In any event, the toll is now, in Mr. Douthat’s phrase, “metastasizing on its own,” as the population-control movement dims “yet sex selection has spread inexorably with access to abortion. . .” The tragedy, as Mr. Douthat puts it at the end of his column, is not that the 160 million girls are “‘missing’. The tragedy is that they’re dead.”

Suddenly the story leads to a surprising intellectual landscape, in which the high road is held not by the liberals, among whom is numbered Ms. Hvistendahl, but by those who have seen through the Malthusian fallacies that so often have been used to justify population control. This story has not been without its journalistic heroes, such as, to name but one, William McGurn of the Wall Street Journal. He was honored in October at a dinner of the Human Life Review, where the editor of The New York Sun spoke of Mr. McGurn and his colleagues “reporting the barbarity of population-control measures in Asia, the backwardness of the preaching of the World Bank, and the signal failures of communism.”

If the story is not new, it has rarely come into view with such clarity as Messrs. Last and Douthat have brought to their reviews of Ms. Hvistendahl’s book. It is going to be illuminating to see what the liberal organs make of the catastrophe being glimpsed in “Unnatural Selection.” By our lights, it is a story that will dwarf whatever one makes of global warming. The toll in the story of the missing girls is easier to count, and the responsibility is more clear. And this is the century in which at least some scientists are predicting that, for all sorts of reasons, the population of the globe will peak and then start to decline. When that happens, the missing girls in their hundreds of millions will be mourned with an unimagined intensity.