Dogs display the greatest diversity in size, shape and behavior of any mammal in the world. And yet, from the tiniest Chihuahua to the largest St. Bernard, all dogs have descended from a common ancestor, the wolf. How did the 300 breeds of dog recognized today come to be so different? And how and why has the modern dog secured a place in history as one of the best loved animals on our planet? This two-part program features scientists who have discovered the answers to these questions by piecing together, for the first time ever, the complex puzzle of canine evolution and design.

Sundays, 1/13-20/08 from 8-9 p.m. ET
Thursdays, 1/17-24/08 from 4:30-5:30 a.m. ET