Why do dogs come in so many sizes, shapes and colors?

Unlike humans dogs come in the most varied sizes, shapes, and colors. As a matter of fact they are the species with the most variables among the known species that have lived in our planet. Just take a glance and compare breeds like Chihuahuas and Neapolitan Mastiffs, or poodles and greyhounds or to beagles and afghans. They are so different in everything from each other and still they share the same genetic structures. Yes, believe or not at a genetic level there is no difference among breeds; it doesn't matter whether they're small or big, red or white, long or short, they all carry the same genes. And how is this possible?

Well, the truth is that dogs genetic structures have been manipulated for thousands of years by men. Men have bred these animals searching for the perfect breed that that matches their needs. So as you can see, we might still be able to learn about new breeds being brought up in the future.