The comment in the Washington Post does not explain but merely describes the practice of modern day slavery and includes the following statement:
"It's highest in Mauritania, a shocking four percent, due in part to social norms tolerating the practice." (Italics mine - I wonder what this could be?? dohhhh. The Washington Post cites slavery in Sub-Saharan countries as a legacy of:
"The legacies of the transatlantic slave trade and European colonialism are still playing out in the region; ethnic divisions and systems of economic exploitation engineered there during the colonial era are still, to some extent, in place. Slavery is also driven by extreme poverty, high levels of corruption and toleration of child "marriages" of young girls to adult men who pay their parents a "dowry.""
What a load of claptrap and very misleading. Slavery existed, often as a African tribe practice, then this was further exacerbated by the arrival of Islam and its slave trade, which is well documented. This started a long time before any Europeans came on the scene to "take their pickings". The Washington Post conveniently overlooked this primary deep rooted legacy. Maybe it is linked to the social norms that were mentioned in the main article. Source:http://www.washingtonpost.com/blogs/worldviews/wp/2013/10/17/this-map-shows-where-the-worlds-30-million-slaves-live-there-are-60000-in-the-u-s/