Academics often talk about between 30 and 60 million "missing girls" in China, apparently killed in the womb or just after birth, thanks to a combination of preference for sons and the country's decades under a repressive one-child policy.
Now researchers in the United States and China think they might have found many - or even most - of them, and argue they might not have been killed after all.
John Kennedy of the University of Kansas and Shi Yaojiang of Shaanxi Normal University have released a study claiming that the births of many of the girls may, in fact, simply not have been registered.
"People think 30 million girls are missing from the population. That's the population of California, and they think they're just gone," said Kennedy, an associate professor of political science said. "Most people are using a demographic explanation to say that abortion or infanticide are the reasons they don't show up in the census and that they don't exist. But we find there is a political explanation." Local officials, they argue, were complicit in the concealment to retain support from villagers, and maintain social stability.
"There is no coordination between cadres saying 'we're all in agreement,"' Kennedy said. "Actually it's just very local. The people who are implementing these policies work for the government in a sense. They are officials, but they are also villagers, and they have to live in the village."