The International Labor Organization (ILO) estimates the number of slaves in the world today at around 21 million. Kevin Bales, of Free the Slaves -- the U.S. affiliate of the world's oldest human-rights organization, the U.K.-based Anti-Slavery International -- (and the author of Disposable People: New Slavery in the Global Economy) puts it at 27 million. Siddharth Kara of Harvard's Carr Center for Human Rights Policy says more than 29 million.
That range represents a tightening consensus. In the 1990s, some accounts had the world's slave population as high as 100 million; others had it as low as 2 million. "It was nuts," says Bales. "I traced all these numbers back. The 100-million number, I finally found this guy in India who'd said it at at UN conference. I asked him, 'How did you get that?' And he said, 'I don't know, it was just a guess.' So nobody had the number."
Bales's 27 million -- which as a statistician he considers a "conservative estimate" -- is derived from secondary-source analysis. "It's still not great," he says, "in the sense that it's not based on random-sample surveys at the grass-roots level. We're doing that now, though, building much sounder numbers, and they're still coming out in the same range. ... So we're getting closer."
In which case, assuming even the rough accuracy of 27 million, there are likely more slaves in the world today than there have been at any other time in human history. For some quick perspective on that point: Over the entire 350 years of the transatlantic slave trade, 13.5 million people were taken out of Africa, meaning there are twice as many enslaved right now as there had been in that whole 350-year span.
