Dogs today come in a mind-blowing array of shapes and sizes, from the diminutive pug, Pekingese, and Pomeranian to the grand Irish Wolfhound, Great Dane, and Saint Bernard. But when did this diversity in canine forms begin? New research shows it dates back many millennia, long before modern breeding practices.Scientists examined the sizes and shapes of 643 skulls of domesticated dogs and their wolf ancestors dating back roughly 50,000 years, identifying the emergence of canine physical