Guests: James Serpell, Bridgett VonHoldt, Elaine Ostrander

Dogs are one of the most diverse mammal species on earth. There are Great Danes and Mastiffs, tiny teacup poodles and Chihuahuas, and all sorts of variations in between. This hour, we are going to look at dogs and their evolution – when, where and how they became domesticated, why they’re so friendly, and why there are so many different breeds. Marty will be joined by JAMES SERPELL, professor of ethics and animal welfare at the University of Pennsylvania School of Veterinary Medicine, BRIDGETT VONHOLDT, assistant professor of ecology and evolutionary biology at Princeton University, and ELAINE OSTRANDER, chief investigator with the National Human Genome Research Institute at the National Institutes of Health.