The economics of contemporary slavery

In the post WWII era debate about the link between economic growth and different relational forms (most notably unfree social relations of production in Third World agriculture) occupied many contributing to discussions in the development decade (the 1960s). This continued to be the case in the mode of production debate (mainly about agrarian transition in India) that spilled over into the 1970s, important aspects of which continue into the present (see the monograph by Brass, 1999, and the 600 page volume edited by Brass and van der Linden, 1997). Central to these discussions was the link between capitalist development and modern forms of unfree labour (peonage, debt bondage, indenture, chattel slavery). Within the domain of political economy it is a debate that has a very long historical lineage, and - accurately presented - never actually went away. Unlike advocacy groups, for which the number of the currently unfree is paramount, those political economists who participated in the earlier debates sought to establish who, precisely, was (or was not) to be included under the rubric of a worker whose subordination constituted a modern form of unfreedom. This element of definition was regarded as an epistemologically necessary precondition to any calculations of how many were to be categorized as relationally unfree.

According to a broader definition used by Kevin Bales of Free the Slaves, another advocacy group linked with Anti-Slavery International, there are 27 million people (though some put the number as high as 200 million) in virtual slavery today, spread all over the world (Kevin Bales, Disposable People). This is, also according to that group:

The largest number of people that has ever been in slavery at any point in world history.
The smallest percentage of the total human population that has ever been enslaved at once.
Reducing the price of slaves to as low as US$40 in Mali for young adult male laborers, to a high of US$1000 or so in Thailand for HIV-free young females suitable for use in brothels (where they frequently contract HIV). This represents the price paid to the person, or parents.
This represents the lowest price that there has ever been for a slave in raw labor terms — while the price of a comparable male slave in 1850 America would have been about US$1000 in the currency of the time (US$38,000 today), thus slaves, at least of that category, now cost one thirtyeighth of their price 150 years ago, although this does not refer to the price of an 1850 slave in Africa.
As a result, the economics of slavery is stark: the yield of profit per year for those buying and controlling a slave is over 800% on average, as opposed to the 5% per year that would have been the expected payback for buying a slave in colonial times. This combines with the high potential to lose a slave (have them stolen, escape, or freed by unfriendly authorities) to yield what are called disposable people — those who can be exploited intensely for a short time and then discarded, such as the prostitutes thrown out on city streets to die once they contract HIV, or those forced to work in mines.