From Wolves to Pugs and Great Danes – The Evolution of Man’s (and Woman’s) Best Friend
Spend a day watching the Westminster Kennel Club Dog Show and it’s hard to believe that a shih tzu shares a common ancestor with an Irish wolfhound. With over 400 recognized dog breeds, the variety is mind boggling. But genetic studies tell us that our canine friends are indeed related, and all dogs trace back to a common ancestor – the gray wolf, Canis lupus.
Enter in thousands of years of human interaction and intervention, and the result is the wide variety of dog breeds proudly strutting across our television screen. The story of how dogs have evolved from wolf to Chihuahua is a fascinating tale that starts with our respective ancestors’ first interactions.
Dogs and humans – an ancient partnership
Most researchers who study canine genetics agree that dogs are really domesticated wolves – their scientific name is Canis lupus familiaris - but the exact time that the relationship between wolves and humans turned from distrust and fear to a mutually beneficial partnership is disputed. A large body of research suggests that dogs were domesticated between 12,500 and 15,000 years ago, but more recent studies establish domestication as early as 130,000 years ago, long before our human ancestors settled into agricultural communities.
Another long-standing controversy surrounds the origins of these earliest domesticated dogs. Evidence pointed to both Asia and Europe as the site of initial domestication, resulting in an unusual scientific tug of war. A 2016 study suggested that dogs were actually domesticated twice –in both Europe and Asia.
A separate study looked at the genetics of more than 150 different dog breeds and unearthed evidence of a “New World Dog” that migrated with humans across the Bering Strait. Archaeological evidence exists of this ancient dog, but the study was the first to show “living evidence of these dogs in modern breeds,” including the Peruvian hairless Dog and the Xoloitzcuintle. Most other dogs in North America are of European descent, brought over by waves of soldiers and settlers.
Beginnings of selective breeding
The same study also revealed other unexpected results. When closely comparing genetics of traditionally herding dog breeds, researchers found one group of dogs seemed to arise from the United Kingdom, another from Northern Europe, and yet another group from Southern Europe. When researchers looked more closely at the different groups, they realized each group used a different strategy to herd their flocks, a pattern borne out in genetic data. This supports the growing theory that multiple human populations started purposeful breeding of dogs independent of one another.
The “Victorian Explosion”
Most dog breeds we recognize today were developed in the last 150 years, spurred by what has become known as the “Victorian Explosion.” During this time in Great Britain, dog breeding intensified and expanded, resulting in many of our most recognizable breeds of dogs.
Breeding for conformational traits continued through the 20th century. The result is the 400+ types of dogs recognized as distinct breeds.
Scroll through pictures of dog breeds from 100 years ago, compared to their current kin, and you can see dramatic changes as dog fanciers selectively bred for traits such as shorter legs (dachshunds were taller back then), and stockier build (German shepherd dogs were lankier at the turn of the last century). The downside of this extensive breeding is loss of genetic diversity and conformation changes with detrimental, breed-specific health consequences.
Enter the 21st Century
As we approach the third decade of the 21st century, technological advances have given scientists a new perspective on our canine companions, including the health risks they share with humans.
Because dogs spontaneously develop some of the same diseases that plague humans, such as cancer, heart disease and obesity, researchers hope that dogs might shed light on how these conditions develop, ultimately leading to treatments that could help both species. One such study is Morris Animal Foundation’s Golden Retriever Lifetime Study that is gathering lifestyle and genetic information on more than 3,000 golden retrievers. This groundbreaking project will provide a wealth of new information that will help identify risk factors for canine diseases, including many cancers. This study also has many translational components that may inform human health risk factors.
To learn more about this study and the Foundation behind the research, visit Morris Animal Foundation and see how they are helping solve health challenges for all breeds.