Our best friends come in a fantastic array of shapes and sizes; a Borzoi looks nothing like a Boston terrier, except for a certain fundamental, ineffable (except to taxonomists) doggyness about them.

From village dogs to toy poodles to mastiffs, dogs come in an astonishing array of shapes, colors and sizes. Today there are estimated to be about 700 million dogs living with or around humans.

Dogs began diversifying thousands of years earlier than previously believed, with clear differences in size and shape appearing over 11,000 years ago. A massive global analysis of ancient skulls shows ...