From Bite to Bark: The Evolution of Dogs

A little goldendoodle puppy may look more like a teddy bear than a wolf. But behind those cute curls is a bit of wild animal.

From fluffy goldendoodles to sleek greyhounds to giant mastiffs — all dogs come from ancient wolves. How those wild wolves turned into dogs is one of the coolest stories of animal evolution.

Taming Wolves

Dogs were the first domesticated animal. This means that they were the first animal that became tame enough to live with humans. People take credit for domesticating dogs, but scientists have figured out that it didn’t happen that way. The wolves tamed themselves. 

“Wolves chose us,” Brian Hare told the news program 60 Minutes. He is an expert on animal evolution. “A population of wolves actually became attracted to humans.”

It wasn’t our fun personalities that won them over. It was our leftovers!

More than 20,000 years ago, humans hunted animals to survive. After feasting and using the most useful parts, they threw away the rest. Some wolves weren’t too afraid of people. These clever wolves realized that the leftovers would make easy meals for them. They started hanging around people to get those tasty treats. Over thousands of years, wolves slowly bonded with people and changed into dogs.

Humans’ Best Friend 

The tamer these wolves became, the more they began to look and act dog-like. They no longer needed their large size and powerful jaws to hunt. So they evolved to be a little smaller. This was better for surviving on scraps. 

It wasn’t only their bodies that became smaller. Their snouts, paws, and teeth also shrunk. Some of their pointy ears flopped down, and their fur became different colors.

All living things pass along many different traits. Traits refer to how a living thing looks, how they behave, and how they are built. Living things pass down traits to their children through microscopic sets of instructions called genes. As wolves evolved into dogs, their genes changed. These changes affected the wolves’ looks and behaviors.

Scientists have found interesting differences between wolf and dog genes. Scientist Bridgett vonHoldt is an expert on the study of genes. She told 60 Minutes that there are genes in dogs that make them friendlier than wolves.

Dogs became good at communicating with humans. They learned how to read our expressions and body language. They even learned some of our spoken words and signals. They also figured out how to attract our attention — by being cute. They learned to rest their chins on our laps or tap us with a paw. They even learned to raise their inner eyebrows in that “puppy eyes” way that people love. According to The New York Times, dogs have a special muscle that helps them raise their eyebrows. Wolves do not.

As the bond between people and dogs grew stronger, dogs made people’s lives easier in many important ways. They helped people hunt. They learned how to herd sheep. They pulled sleds piled with our stuff. They protected us and kept us company. As the saying goes, dogs became our best friends. 

But the amazing story of how wolves evolved into dogs doesn’t explain how we ended up with pups as different as Chihuahuas and St. Bernards. That’s where people came in.

The Best Dog for the Job

Over time, people created dog breeds. They did it through a practice called selective breeding. People picked the “best dogs” — ones with traits the people really liked and wanted to see in other dogs. Then, they made sure the dogs had puppies. The desired traits were passed on to some of the puppies, so people repeated the practice. As a trait became stronger in each generation of dog, the pups with the trait became more different. Eventually, these special traits became a unique breed. 

Of course, not everyone agreed on the “best dogs” or the most desirable traits. Some people wanted dogs with an excellent sense of smell or the ability to run fast. Both traits were helpful in hunting. Others bred nimble dogs that could herd sheep. They also wanted big, patient dogs to guard the livestock. And other people needed strong dogs with a lot of energy to pull sleds over snow. All of these dogs became different breeds.

Even More Dog Breeds

For many years, people bred dogs for work or protection. But by the mid-1800s, people realized that they loved having dogs simply as pets, too. They began to breed little dogs that could sit on their laps. They bred dogs with interesting looks that they could show off in a new competition: dog shows.

Today, we have more than 400 different dog breeds according to National Geographic’s Dog Breed Guide. And that’s not even counting the “designer dog” crossbreeds. This includes breeds like cockapoos (cocker spaniel-poodle), puggles (pug-beagle), goldendoodles (golden retriever-poodle), and chiweenies (Chihuahua-dachshund). Or the many mixed-breeds called “mutts.”

Dogs now come in many different shapes, colors, and sizes. They also have many different types of behaviors. This makes dogs the most diverse land mammal. The largest dogs are a whopping 40 times bigger than the smallest dogs! That’s quite a change from the lone wolf.