NATURE’s two-part special Dogs That Changed the World tells the epic story of the wolf’s evolution, how “man’s best friend” changed human society and how we in turn have radically transformed dogs.

From the tiniest Chihuahua to the powerful and massive English Mastiff, modern domesticated dogs come in a bewildering array of shapes and sizes, with an equally diverse range of temperaments and behaviors. And yet, according to genetics, all dogs evolved from the savage and wild wolf — in a transformation that occurred just 15,000 years ago.

Part One: The Rise of the Dog

Learn how the domestication of dogs might have taken place, including the theory of biologist Raymond Coppinger that it was the animals themselves — and human trash — that inspired the transformation. The genetic analysis of Peter Savolainen of the Royal Institute of Technology in Sweden has placed the origins of domesticated dogs — and those of the first dog — in East Asia. You’ll also discover 14 dog breeds that controversial genetic studies show are the most ancient — and the best living representatives of the ancestors to all living dogs.

Preview Part Two: Dogs by Design

Over 400 breeds of dog are recognized around the world, each unique for its personality, habits, and form. Most of these breeds exploded onto the scene over the past 150 years, spurred by the Victorian-era passion for the “dog fancy” — the selective breeding of dogs to enhance particular characteristics. By tinkering with its genetics, humans made the dog the most varied animal species on the planet — and also created a host of hereditary health problems.

Despite the plethora of new shapes and sizes, dogs have retained the instincts bred into their ancestors by thousands of years of work: the urge to herd or hunt, to dig and to guard. In Part Two, “Dogs by Design,” you’ll discover how these hard-wired behaviors help different types of dogs, from hounds to herders, excel at different tasks (and why it can sometimes be so difficult to train them to do otherwise). You’ll also learn how dogs’ finely tuned senses are serving humans and saving lives.