FROM THE FIRST domesticated canine 15,000 years ago, dogs have evolved into an incredible variety of shapes, sizes, and temperaments (witness the pug!). Over the millennia, people molded those dogs into companions and workers. The pug, for one, has always been a companion. Today, each breed has written guidelines, known as standards, that describe how each type of dog should look and act. Here, you'll learn about the pug's appearance and temperament.