How 400-Plus Dog Breeds Evolved From the Grey Wolf

Analysis by Dr. Karen Shaw Becker

grey wolf

Story at-a-glance -

  • Genetic elements from a “new world dog,” which migrated across the Bering Strait with humans, persist in some modern breeds, such as the Peruvian hairless dog and the Xoloitzcuintle
  • Researchers analyzed the genetics of 161 pure breeds sampled from multiple areas of the globe, suggesting a two-step process led to the creation of different breeds
  • The first diversification may have occurred thousands of years ago, during which dogs were selected for their skills, while the second diversification occurred just a few hundred years ago, in which dogs were bred primarily for physical traits
  • The analysis revealed 23 clades of breeds (clades are groups of organisms believed to share a common ancestor) among the 161 modern-day breeds analyzed
  • While most dog breeds emerged within the last 200 years, during a period of intense dog breeding known as the “Victorian Explosion,” the species’ actual origins may date back to the Ice Age

There are more than 400 dog breeds, with a tremendous variety of size and shape — from tiny Chihuahuas to giant great Pyrenees. Despite the diversity, all dogs are believed to share one common ancestor — the grey wolf, or Canis lups. As the Morris Animal Foundation points out, dogs’ scientific name, Canis lupus familiaris, speaks to the fact that most scientists agree dogs are basically domesticated wolves,1 but exactly how the transition occurred remains a mystery.

At some point, it’s thought that wolves may have started hanging around humans for food scraps, or humans may have taken to feeding some tamer wolves, eventually enjoying their help with hunting, work and companionship. When this mutually beneficial relationship emerged is a topic of great interest among researchers, with some studies suggesting domestication took place as recently as 12,500 to 15,000 years ago.2

Other research, however, suggests dogs were domesticated much earlier, perhaps up to 130,000 years ago, which changes the course of dogs’ domestication history.

‘New World Dog’ May Persist in Some Modern Breeds

According to a study published in Cell Reports,3 genetic elements from a “new world dog,” which migrated across the Bering Strait with humans, persist in some modern breeds, such as the Peruvian hairless dog and the Xoloitzcuintle.4

The researchers analyzed the genetics of 161 pure breeds sampled from multiple areas of the globe, suggesting a two-step process led to the creation of different breeds, “beginning with ancient separation by functional employment followed by recent selection for physical attributes.”5

In short, there may have been two major diversification periods for dogs — one that occurred thousands of years ago, during which dogs were selected for their skills, and one that occurred just a few hundred years ago, in which dogs were bred primarily for physical traits.6

The analysis revealed 23 clades of breeds (clades are groups of organisms believed to share a common ancestor) among the 161 modern-day breeds. The primary breed types were likely created via selection and segregation of dog populations before breeds were formally recognized. The researchers explained:

“Breed prototypes have been forming through selective pressures since ancient times depending on the job they were most required to perform. A second round of hybridization and selection has been applied within the last 200 years to create the many unique combinations of traits that modern breeds display.”7

Giant size used for guarding is thought to have been one of the earliest traits by which breeds were segregated thousands of years ago, as the analysis found large size to exist multiple times across clades, despite no mixing of the groups:

“[T]he Mediterranean and the European mastiffs … required large size for guarding; however, each used that size in a different way, a fact that was recognized at least 2,000 years ago. The flock guards use their size to defeat animal predators, while the mastiffs use their size to keep human predators at bay, often through fierce countenance rather than action.”8

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Ancient Breeds Show Hybridization With Herding Dogs

Also intriguing, herding dog breeds were found to have origins in different parts of the world, including the U.K., Northern Europe and Southern Europe, which suggests people in different geographic regions may have been purposefully breeding dogs for that purpose.9

“We show that many traits such as herding, coursing, and intimidating size, which are associated with specific canine occupations, have likely been developed more than once in different geographical locales during the history of modern dog,” according to the study.10 Further:

“Dogs have been in the Americas for more than 10,000 years, likely traveling from East Asia with the first humans. However, studies of mitochondrial DNA suggest that the original New World dogs were almost entirely replaced through European contact and additional Asian migrations.

As colonists came to the Americas from the 16th to the 19th centuries, they brought Old World livestock, and therefore the dogs required to manage and tend the livestock, to the New World.

Many of the newly introduced animals outcompeted the native animals, which may explain the surprising and very strong herding dog signature in the native hairless breeds of South and Central America that were not developed to herd. In this analysis, we observe that the ancient hairless breeds show extensive hybridization with herding dogs from Europe and, to a lesser extent, with each other.”11

Previous research revealed that Chinese Cresteds, Xolos and Peruvian hairless breeds share the same dominant gene mutation, which may give clues to the dogs' origins and possible relation, with the researchers noting it could be due to early trade between Asia and the new world or prehistoric migration from Asia across the Bering Strait.12

The ancient Aztecs in Mexico considered Xolos to be sacred guides for souls in the afterlife, while Peruvian hairless dogs lived during the Incan Empire. It's thought that Chinese Cresteds may have come from African hairless dogs. However, although these breeds were "derived from or crossed with each other prior to breed establishment," each has very different traits today.

Did Dogs First Become Domesticated During the Ice Age?

While most dog breeds emerged within the last 200 years, during a period of intense dog breeding known as the “Victorian Explosion,”13 the species’ actual origins may date back to the Ice Age. An analysis of Paleolithic-era teeth revealed further evidence of two groups of canids —“one dog-like and the other wolf-like”14 — existing at a 28,500-year-old fossil site.

Dental differences ended up revealing this surprising finding. A dental microwear texture analysis was performed on the ancient teeth, which identified distinctive microwear patterns on the differing canids.15 The dog-like canids, which the researchers called “protodogs,” had larger wear scars that suggest they ate more hard, brittle foods such as bones, which may have been the scraps offered to them by humans.

The wolf-like canids, on the other hand, had smaller scars, which could indicate they ate more flesh-based food, such as mammoth flesh, obtained via their own hunts. While it may never be known exactly when, or how, dogs evolved from wolves, the important aspect is that they did, as it’s hard to imagine what a modern world would be like without them.