Thanks for posting the link brujo, I was unable to do so as it was unavailable at the time when I checked the NG website.
Just to mention - my parents went on a South America cruise over Thanksgiving and were in Montevideo, Uruguay. They told me while in Montevideo they had heard that the Tango actually originated there rather then in Argentina.
If you haven't followed the multimedia link on the National Geographic article (click the "Sights and Sounds" button), make sure you do. It's wonderfully done, with incredible photos, music and voiceover track that work together to create a great piece of digital storytelling.