Living in the West, it's easy to forget that one-sixth of the world's population subsists without sustainable sources of food, medical care, or housing. 

More than a billion people around the world are believed to live on a dollar a day... or  less. While the circumstances leading to that sort of poverty are varied and complicated, the situations faced by the planet's poorest are depressingly familiar. 

Now we get an on the ground look at that world, in a new work by Thomas A. Nazario. He is the founder of a nonprofit The Forgotten International, and the author of the vividly reported and beautifully photographed, Living on a Dollar a Day: The Lives and Faces of the World's Poor.

My conversation with Thomas Nazario: