Dogs come in a wide variety of shapes and sizes, from Mastiffs and Great Danes to Chihuahuas and teacup Poodles, and are all part of the same Canis lupus familiaris species. But how did so many different breeds come to be, and just how closely related are they? Geneticists Heidi Parker and Elaine Ostrander, along with a team of colleagues from the National Human Genome Research Institute, set forth to figure that out; the results were published a little over a year ago.










