The results suggest all dogs derive from a single extinct wolf population – or perhaps a few very closely related ones. If there were multiple domestication events around the world, these other lineages did not contribute much DNA to later dogs.
Dr Pontus Skoglund, co-author of the study and group leader of the Ancient Genomics laboratory at Londons Crick Institute, told BBC News: “Dogs are really unique in being this quite strange thing if you think about it, when all people were still hunter gatherers, they domesticate what is really a wild carnivore – wolves are pretty frightening in many parts of the world.
The research fills in some of the gaps in the natural history of our close animal companions.
A study of dog DNA has shown that our “best friend” in the animal world may also be our oldest one.
But at some point, perhaps after the onset of the Bronze Age, a single dog lineage spread widely and replaced all other dog populations on the continent. This pattern has no counterpart in the genetic patterns of people from Europe.
How did dogs become man’s best friend?
Perhaps more intriguing then exactly when or where dogs became domesticated is the question of how. Was it really the result of a solitary hunter befriending an injured wolf? That theory hasn’t enjoyed much scientific support.
One similar theory argues that early humans somehow captured wolf pups, kept them as pets, and gradually domesticated them. This could have happened around the same time as the rise of agriculture, about 10,000 years ago. The oldest fossils generally agreed to be domestic dogs date to about 14,000 years, but several disputed fossils more than twice that age may also be dogs or at least their no longer entirely wolf ancestors.
Since more recent genetic studies suggest that the date of domestication occurred far earlier, a different theory has gained the support of many scientists. “Survival of the friendliest” suggests that wolves largely domesticated themselves among hunter-gatherer people.
“That the first domesticated animal was a large carnivore, who would have been a competitor for food—anyone who has spent time with wild wolves would see how unlikely it was that we somehow tamed them in a way that led to domestication,” says Brian Hare, director of the Duke University Canine Cognition Center.
But, Hare notes, the physical changes that appeared in dogs over time, including splotchy coats, curly tails, and floppy ears, follow a pattern of a process known as self-domestication. It’s what happens when the friendliest animals of a species somehow gain an advantage. Friendliness somehow drives these physical changes, which can begin to appear as visible byproducts of this selection in only a few generations.
“Evidence for this comes from another process of domestication, one involving the famous case of domesticated foxes in Russia. This experiment bred foxes who were comfortable getting close to humans, but researchers learned that these comfortable foxes were also good at picking up on human social cues,” explains Laurie Santos, director of the Canine Cognition Center at Yale University. The selection of social foxes also had the unintended consequence of making them look increasingly adorable—like dogs.
Hare adds that most wolves would have been fearful and aggressive towards humans—because that’s the way most wolves behave. But some would have been friendlier, which may have given them access to human hunter-gatherer foodstuffs..
“These wolves would have had an advantage over other wolves, and the strong selection pressure on friendliness had a whole lot of byproducts, like the physical differences we see in dogs,” he says. “This is self-domestication. We did not domesticate dogs. Dogs domesticated themselves.”
A study last year provided some possible genetic support for this theory. Evolutionary biologist Bridgette von Holdt, of Princeton University, and colleagues suggest that hypersocial behavior may have linked our two species and zero in on a few genes that may drive that behavior.
“Generally speaking, dogs display a higher level of motivation than wolves to seek out prolonged interactions with humans. This is the behavior I’m interested in,” she says.
Von Holdt’s research shows that the social dogs she tested have disruption to a genomic region that remains intact in more aloof wolves. Interestingly, in humans genetic variation in the same stretch of DNA causes Williams-Beuren syndrome, a condition characterized by exceptionally trusting and friendly behaviors. Mice also become more social if changes occur to these genes, previous studies have discovered.
The results suggest that random variations to these genes, with others yet unknown, may have played a role in causing some dogs to first cozy up with humans.
“We were able to identify one of the many molecular features that likely shape behavior,” she adds.
The discovery could push back the date for the earliest dog by 17,700 years, since the second oldest known dog, found in Russia, dates to 14,000 years ago.
An international team of scientists has just identified what they believe is the worlds first known dog, which was a large and toothy canine that lived 31,700 years ago and subsisted on a diet of horse, musk ox and reindeer, according to a new study.
Isotopic analysis of the animals bones found that the earliest dogs consumed horse, musk ox and reindeer, but not fish or seafood. Since the Aurignacians are believed to have hunted big game and fished at different times of the year, the researchers think the dogs might have enjoyed meaty handouts during certain seasons.
“I think it is possible that the dogs were used for tracking, hunting, and transport of game,” she said. “Transport could have been organized using the dogs as pack animals. Furthermore, the dogs could have been kept for their fur or meat, as pets, or as an animal with ritual connotation.”
For the study, which has been accepted for publication in the Journal of Archaeological Science, the scientists analyzed 117 skulls of recent and fossil large members of the Canidae family, which includes dogs, wolves and foxes.
A Brief History of Dogs – How We Domesticated Dogs
An international team of scientists has just identified what they believe is the worlds first known dog, which was a large and toothy canine that lived 31,700 years ago and subsisted on a diet of horse, musk ox and reindeer, according to a new study.
The discovery could push back the date for the earliest dog by 17,700 years, since the second oldest known dog, found in Russia, dates to 14,000 years ago.
Remains for the older prehistoric dog, which were excavated at Goyet Cave in Belgium, suggest to the researchers that the Aurignacian people of Europe from the Upper Paleolithic period first domesticated dogs. Fine jewelry and tools, often decorated with depictions of big game animals, characterize this culture.
If Paleolithic dogs still existed as a breed today, they would surely win best in show for strength and biting ability.
“In shape, the Paleolithic dogs most resemble the Siberian husky, but in size, however, they were somewhat larger, probably comparable to large shepherd dogs,” added Germonpré, a paleontologist at the Royal Belgian Institute of Natural Sciences.
For the study, which has been accepted for publication in the Journal of Archaeological Science, the scientists analyzed 117 skulls of recent and fossil large members of the Canidae family, which includes dogs, wolves and foxes.
Skeletal analysis revealed, “the Paleolithic dogs had wider and shorter snouts and relatively wider brain cases than fossil and recent wolves,” said Germonpré, who added that their skulls were also somewhat smaller than those of wolves.
DNA studies determined all of the canids carried “a substantial amount of genetic diversity,” suggesting that past wolf populations were much larger than they are today.
Isotopic analysis of the animals bones found that the earliest dogs consumed horse, musk ox and reindeer, but not fish or seafood. Since the Aurignacians are believed to have hunted big game and fished at different times of the year, the researchers think the dogs might have enjoyed meaty handouts during certain seasons.
Germonpré believes dog domestication might have begun when the prehistoric hunters killed a female wolf and then brought home her pups. Recent studies on silver foxes suggest that when the most docile pups are kept and cared for, it takes just 10 generations of breeding for morphological changes to take effect.
“I think it is possible that the dogs were used for tracking, hunting, and transport of game,” she said. “Transport could have been organized using the dogs as pack animals. Furthermore, the dogs could have been kept for their fur or meat, as pets, or as an animal with ritual connotation.”
Ancient, 26,000-year-old footprints made by a child and a dog at Chauvet Cave, France, support the pet notion. Torch wipes accompanying the prints indicate the child held a torch while navigating the dark corridors accompanied by a dog.
Susan Crockford, a University of Victoria anthropologist and an evolutionary biologist at Pacific Identifications, Inc. in Canada, told Discovery News that “this is an important paper.”
Crockford, however, is not convinced the Aurignacians domesticated dogs. She instead suspects dogs may have undergone “self-domestication” from wolves more than once over history, which could explain why the animals appear and then seemingly disappear from the archaeological record.
Crockford details the possible process in her book, Rhythms of Life: Thyroid Hormone and the Origin of Species. She theorizes that the genes that control thyroid rhythms, allowing individuals to adapt to changing environmental conditions, can, over time, lead to the evolution of new species.
“I think that for these Paleolithic-age canids, the process got started and then stopped, leaving some individual wolves with a few of the features of early dogs, but not all of them,” she said.
Germonpré does not dismiss Crockfords theory, which she described as “a very interesting model.” She hopes more information will come to light in the future about these very early canines. An extensive study on their teeth and jaws is already in the works.