This video explores how people developed the different breeds of dogs that exist today through selective breeding.
DNA and archaeological evidence show that dogs evolved from a species of domesticated wolf. In a span of less than 10,000 years, breeders have changed body shapes and behaviors of dogs through artificial selection. The end of the video includes interview clips from a couple of breeders about how they value different dog traits.
This clip is from a 2005 Holiday Lecture Series, Evolution: Constant Change and Common Threads.