Researchers now believe that domesticated dogs originally descended from wolves in northern Africa. The lead scientist--Adam Boyko-- studied the DNA from all kinds of dogs, but found that "village dogs"--semi feral dogs living near human settlements--had the most genetic diversity. High genetic diversity means that they are near the place of origin. The DNA of dogs in other areas of Africa was less diverse--similar to what you might find in an American shelter-meaning that they were mixes of modern breeds.
The really interesting thing is that so-called "African" dogs, like Rhodesian ridgebacks, don't actually have African ancestry.
National Geographic's article about this discovery also provides a little backstory--Researchers formerly seemed convinced that dogs originated in East Asia. Now it is not so clear. Boyko told National Geographic that these studies could help us understand ancient human migration patterns...because where people go, dogs have usually followed!
[Wags to Lisa in Georgia for the tip!!]