Here's what popular dog breeds looked like before and after 100 years of breeding
Dogs have been our furry companions for thousands of years, but they didn't always look the way they do today. Many well-known breeds have changed a lot physically in the last century, thanks to humans.
By identifying specific traits — such as size, coat color, and demeanor — and allowing only those animals to mate, we've created at least 167 different "breeds," or groups of dogs with unique physical and mental characteristics. Still, they're all part of the same species.