In Dog DNA, Small Size Has an Ancient Pedigree The New York TimesGene mutation that helps make 'toy' dog breeds so small existed in wolves 54000 years ago Livescience.comYes, those tiny dogs descended from wolves NBC NewsBig dog, little dog: mutation explains range of canine sizes Nature.comChihuahuas share gene that makes them small with ancient wolves, study suggests The IndependentView Full Coverage on Google News