Though dogs are humanity’s oldest and most consistent animal friend, scientists have long struggled to figure out just how Canis familiaris came to be. Though researchers agree dogs are descended from wild wolves, they aren’t sure when and where domestication occurred. And as Tina Hesman Saey at Science News reports, a new study has revived the debate, suggesting that dogs were domesticated one time between 20,000 and 40,000 years ago.
Dog domestication has gotten a lot of attention in recent years. In 2016, researchers looked at the mitochondrial DNA of modern and ancient dog species, determining that dogs come from two different wolf populations, one found in Europe and one found in Asia. That means that wolves would have been domesticated in two different places, with the two lineages eventually mixing in modern dogs.
But this latest research contradicts the double-domestication hypothesis. According to Ben Guarino at the Washington Post, researchers looked at the well-preserved DNA of two ancient dogs found in Germany, one 7,000 years old and one 4,700 years old, as well as the complete genomes of 100 modern dogs and snippets of DNA from 5,600 other wolves and dogs.
They traced the rate of mutations in the over time in the dog genomes. This technique, which creates a “molecular clock,” indicates that dogs diverged from wolves 36,900 years ago to 41,500 years ago in a single domestication event. But they can’t determine exactly where the split occurred. About 20,000 years later, the molecular clock indicates dogs split into European and Asian groups. They published their results in the journal Nature Communications
Not everyone is convinced by the study. Greger Larson, Oxford evolutionary biologist and author of the earlier domestication study, tells Guarino that the latest research does not explain the “ridiculously deep split” between the genetics of ancient European and Asian dogs. He also points out that while ancient dog bones have been found in far eastern Asia and western Europe, the middle of Eurasia seems to be empty of dog bones, suggesting that there were two ancient populations, separated by vast distances.
Krishna Veeramah, a palaeogeneticist at Stony Brook University and author of the new study says he doesn’t anticipate that the paper will put the issue to rest. “More ancient dog DNA from genomes will ultimately solve the problem,” he tells Rachael Lallensack at Nature. Researchers are hoping to find more geographically diverse DNA from dogs as well as samples from different time periods.
Whether it happened once or twice, how and why did domestication occur?
As Veeramah tells Helen Briggs at the BBC that it’s likely dogs evolved from wolves that began hanging around human camps, scavenging their scraps. ”Those wolves that were tamer and less aggressive would have been more successful at this,” he says. “While the humans did not initially gain any kind of benefit from this process, over time they would have developed some kind of symbiotic relationship with these animals, eventually evolving into the dogs we see today.”
For now, however, exactly when and where Fido first approached humans will remain a mastiff question.
For my money the origins of the domestic dog are as Krishna Veeramah puts it: ”Those wolves that were tamer and less aggressive would have been more successful at this,” he says. “While the humans did not initially gain any kind of benefit from this process, over time they would have developed some kind of symbiotic relationship with these animals, eventually evolving into the dogs we see today.”
Science confirms what we instinctively understand!
That the way a dog looks deep into our eyes is more than emotional froth!
Follower of this blog, Anita, left a comment to yesterday’s post. This is what she wrote (my emphasis):
This has been a wonderful compilation of awesome photos. You must do it again sometime. Dogs are so wonderful and such great companions. They do have eyes that see straight through our very souls and ready to love us at the drop of a hat.
One of our dogs here at home, Oliver, has those eyes. When he stares into my own eyes it feels as though at some mystical level Oliver and I are connected.
So imagine my surprise when reading yesterday the lead essay in The Smithsonian about the evolution of the domesticated dog and me coming across this:
The relationship has become so close that even our brains are in sync. Witness a study showing that dogs hijack the human brain’s maternal bonding system. When humans and dogs gaze lovingly into one another’s eyes, each of their brains secretes oxytocin, a hormone linked to maternal bonding and trust.
In other words, science confirms what I experience as being real!! (Undoubtedly shared by many of you!)
Long ago, before your four-legged best friend learned to fetch tennis balls or watch football from the couch, his ancestors were purely wild animals in competition—sometimes violent—with our own. So how did this relationship change? How did dogs go from being our bitter rivals to our snuggly, fluffy pooch pals?
The new drama Alpha answers that question with a Hollywood “tail” of the very first human/dog partnership.
Europe is a cold and dangerous place 20,000 years ago when the film’s hero, a young hunter named Keda, is injured and left for dead. Fighting to survive, he forgoes killing an injured wolf and instead befriends the animal, forging an unlikely partnership that—according to the film—launches our long and intimate bond with dogs.
Just how many nuggets of fact might be sprinkled throughout this prehistoric fiction?
We’ll never know the gritty details of how humans and dogs first began to come together. But beyond the theater the true story is slowly taking shape, as scientists explore the real origins of our oldest domestic relationship and learn how both species have changed along canines’ evolutionary journey from wolves to dogs.
When and where were dogs domesticated?
Pugs and poodles may not look the part, but if you trace their lineages far enough back in time all dogs are descended from wolves. Gray wolves and dogs diverged from an extinct wolf species some 15,000 to 40,000 years ago. There’s general scientific agreement on that point, and also with evolutionary anthropologist Brian Hare’s characterization of what happened next. ’The domestication of dogs was one of the most extraordinary events in human history,” Hare says.
But controversies abound concerning where a long-feared animal first became our closest domestic partner. Genetic studies have pinpointed everywhere from southern China to Mongolia to Europe.
Scientists cannot agree on the timing, either. Last summer, research reported in Nature Communications pushed likely dates for domestication further back into the past, suggesting that dogs were domesticated just once at least 20,000 but likely closer to 40,000 years ago. Evolutionary ecologist Krishna R. Veeramah, of Stony Brook University, and colleagues sampled DNA from two Neolithic German dog fossils, 7,000 and 4,700 years old respectively. Tracing genetic mutation rates in these genomes yielded the new date estimates.
“We found that our ancient dogs from the same time period were very similar to modern European dogs, including the majority of breed dogs people keep as pets,” explained Dr. Veeramah in a release accompanying the study. This suggests, he adds, “that there was likely only a single domestication event for the dogs observed in the fossil record from the Stone Age and that we also see and live with today.”
Comparing these genomes with many wolves and modern dog breeds suggested that dogs were domesticated in Asia, at least 14,000 years ago, and their lineages split some 14,000 to 6,400 years ago into East Asian and Western Eurasian dogs .
But because dog fossils apparently older than these dates have been found in Europe, the authors theorize that wolves may have been domesticated twice, though the European branch didn’t survive to contribute much to today’s dogs. Greger Larson, director of the Wellcome Trust Palaeogenomics & Bio-Archaeology Research Network at Oxford University, suggests that the presence of older fossils in both Europe and Asia, and the lack of dogs older than 8,000 years in between those regions, supports such a scenario.
“Our ancient DNA evidence, combined with the archaeological record of early dogs, suggests that we need to reconsider the number of times dogs were domesticated independently. Maybe the reason there hasn’t yet been a consensus about where dogs were domesticated is because everyone has been a little bit right,′ Larson said in a statement accompanying the study.
Perhaps more intriguing than 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.
How have dogs changed since becoming our best friends?
Though the origins of the dog/human partnership remain unknown, it’s becoming increasingly clear that each species has changed during our long years together. The physical differences between a basset hound and wolf are obvious, but dogs have also changed in ways that are more than skin (or fur) deep.
But, Yale’s Laurie Santos says, dogs may have compensated in other interesting ways. They’ve learned to use humans to solve problems.
“Several researchers have presented dogs and wolves with an impossible problem (e.g., a puzzle box that can’t be opened or a pulling tool that stops working) and have asked how these different species react,” Santos explains. “Researchers have found that wolves try lots of different trial and error tactics to solve the problem— they get at it physically. But at the first sign of trouble, dogs do something different. They look back to their human companion for help. This work hints that dogs may have lost some of their physical problem-solving abilities in favor of more social strategies, ones that rely on the unique sort of cooperation domesticated dogs have with humans. This also matches the work showing that dogs are especially good at using human social cues.”
The relationship has become so close that even our brains are in sync. Witness a study showing that dogs hijack the human brain’s maternal bonding system. When humans and dogs gaze lovingly into one another’s eyes, each of their brains secretes oxytocin, a hormone linked to maternal bonding and trust. Other mammal relationships, including those between mom and child, or between mates, feature oxytocin bonding, but the human/dog example is the only case in which it has been observed at work between two different species.
The intimacy of this relationship means that, by studying dogs, we may also learn much about human cognition.
We may never know the exact story of how the first dogs and humans joined forces, but dogs have undoubtedly helped us in countless ways over the years. Still, only now may we be realizing that by studying them, they can help us to better understand ourselves.
I can do no better than to repeat those last two sentences of the essay by Brian Handwerk:
We may never know the exact story of how the first dogs and humans joined forces, but dogs have undoubtedly helped us in countless ways over the years. Still, only now may we be realizing that by studying them, they can help us to better understand ourselves.
For, boy of boy, do we humans need help when it comes to better understanding ourselves!
The first humans to populate the Americas arrived from Siberia via the Bering land bridge around 16,000 years ago. Man’s best friend, the domesticated dog, didn’t arrive for another 6,000 years or so, crossing over just in time to avoid the land bridge’s collapse, but archaeological evidence suggests that the two species lived in harmony for thousands of years—at least until 1492, the year Columbus sailed the ocean blue.
According to a study published in Science on Thursday, “pre-contact” American dogs possessed a unique genetic signature derived not from the North American wolf, as previously thought, but from domesticated Siberian ancestors. Today, that singular genome has all but disappeared, eradicated by the 15th-century arrival of European settlers and their canine companions.
National Geographic’s Maya Wei-Haas explains that European dogs, like their human owners, probably carried diseases that pre-contact dogs were unequipped to fend off. The colonists preferred European breeds and discouraged their pets from mating with the native dogs, which study co-author Angela Perri, a zooarchaeologist at Durham University, says were viewed as “wild” and “vicious.”
“This study demonstrates that the history of humans is mirrored in our domestic animals,” Greger Larson, director of the Palaeo-BARN at Oxford and senior author of the study, said in a statement. “People in Europe and the Americas were genetically distinct, and so were their dogs. And just as indigenous people in the Americas were displaced by European colonists, the same is true of their dogs.”
To trace the story of these pre-contact dogs, researchers studied DNA found in the mitochondria of 71 North American and Siberian dog bones. The remains, which date from roughly 10,000 to 1,000 years ago, included those of the Koster dogs, a group of four domesticated canines discovered at a burial site in western Illinois during the 1970s. (A second study, newly published in pre-print server Biorxiv, further discusses these early dogs.) As Science’s David Grimm notes, the Koster pups lived about 10,000 years ago, making them the oldest known dogs in the Americas. Perri, referencing the animals’ small, slender stature, tells Grimm that “it wouldn’t be surprising if they were all used as hunting dogs.”
DNA analysis allowed the scientists to identify pre-contact dogs’ closest relatives: a group of dogs native to Zhokhov Island, a frigid Arctic site situated about 300 miles north of the Russian mainland. The Atlantic’s Ed Yong writes that these dogs were the first to be bred for a specific purpose, namely pulling their humans’ sleds.
In addition to shedding light on the first American dogs’ origins, the study offers insights on pre-contact dogs’ connections—or rather, lack of connections—with modern dogs. Researchers compared the 71 ancient genomes with DNA from more than 5,000 modern dogs, including breeds like chihuahuas and Carolina dogs, which are commonly thought to be descended from indigenous populations. The highest level of pre-contact DNA conclusively found in any of the modern dogs was four percent, a negligible result, the New York Times’ James Gorman reports.
The team’s findings suggest that modern American dogs are descended solely from Eurasian breeds introduced by European settlers. Perri tells Wei-Haas that the scientists expected to find evidence of interbreeding between the pre-contact pups and the new arrivals. Instead, they realized that the native dogs had virtually vanished.
“It is fascinating that a population of dogs that inhabited many parts of the Americas for thousands of years, and that was an integral part of so many Native American cultures, could have disappeared so rapidly,” Laurent Frantz, study co-author and evolutionary geneticist at Queen Mary University of London, said in a statement.
Oddly enough, scientists found that the closest surviving trace of pre-contact dogs’ DNA is found in a sexually transmitted canine cancer. The Los Angeles Times’ Deborah Netburn writes that the disease, known as canine transmissible venereal tumor, stems from the genetic mutation of a single North American dog that lived up to 8,225 years ago. The tumor cells spread through mating and carry a copy of that original DNA, allowing researchers to paint a clear picture of the “founding dog,” or patient zero.
Elaine Ostrander, chief of the cancer genetics and comparative genomics branch at the National Human Genome Research Institute, tells Wei-Haas, “It’s the world’s oldest continuously propagated cell line, which is really, really remarkable.”
What a delight to read this latest scientific news.
There’s so much ‘doom and gloom’ to be seen on the news services across the world that a genuine discovery that enlarges the mind is always a treat. Now make that a discovery about our dogs. Better still, let the BBC do it for you.
How did dogs become our best friends? New evidence
By Helen BriggsBBC News, 19 July 2017
Dogs most probably evolved from wolves at a single location about 20,000 to 40,000 years ago, a study suggests.
Previously, it had been thought that dogs were tamed from two populations of wolves living thousands of miles apart.
Researchers studied DNA from three dogs found at archaeological sites in Germany and Ireland that were between 4,700 and 7,000 years old.
The ancient canines share ancestry with modern European dogs.
By looking at the rates of change to the DNA from the oldest specimen, scientists were able to place the timing of the domestication of dogs to between 20,000 and 40,000 years ago.
Krishna Veeramah of Stony Brook University in New York is a researcher on the study.
He said the process of dog domestication began when a population of wolves moved to the outskirts of hunter-gatherer camps to scavenge for leftovers.
”Those wolves that were tamer and less aggressive would have been more successful at this,” he explained.
“While the humans did not initially gain any kind of benefit from this process, over time they would have developed some kind of symbiotic relationship with these animals, eventually evolving into the dogs we see today.”
The story of how dogs came to be tamed from wolves is complex and hotly debated.
Scientists believe dogs started moving around the world, perhaps with their human companions, about 20,000 years ago.
By 7,000 years ago, they were pretty much everywhere, although they were not the kind of dogs that we would consider pets.
”They would likely have resembled dogs we today call village dogs, which are free-breeding that did not live in specific people’s houses and have a similar look to them across the world,” said Dr Veeramah.
The dogs were later bred for their skills as hunters, herders or gundogs, eventually creating hundreds of modern breeds.
The research, published in Nature Communications, suggests even the dog breeds and village dogs found in the Americas and Pacific Islands are almost completely derived from recent European dog stock.
This is probably due to prolific dog breeding in Victorian times.
”In this regard, it appears therefore that our 7,000-year, Neolithic-old dog from Europe is virtually an ancestor to most modern breed dogs found throughout the world,” said Dr Veeramah.
”This ancestral relationship may even stretch back to the oldest dog fossil we know of, which is approximately 14,000 years old from Germany.”
Previous evidence suggested that the first domestic dogs appeared on opposite sides of the Eurasian continent more than 12,000 years ago.
Later, the eastern dogs moved with migrating humans and bred with those from the west, according to this theory.
Dr Greger Larson of the University of Oxford said it was great to see more ancient dog genomes being published.
“There is a fascinating story here and we’re only just scraping the surface,” he said.
“The more we get the more we might have a shot at finally unravelling the story of how we became such good friends over such a long time.”
Study Reveals Origin of Modern Dog Has a Single Geographic Origin
Reported in Nature Communications, the finding counters previous research that suggested two domestication events led to the modern dog
STONY BROOK, N.Y., July 18, 2017 – By analyzing the DNA of two prehistoric dogs from Germany, an international research team led by Krishna R. Veeramah, PhD, Assistant Professor of Ecology & Evolution in the College of Arts & Sciences at Stony Brook University, has determined that their genomes were the probable ancestors of modern European dogs. The finding, to be published in Nature Communications, suggests a single domestication event of modern dogs from a population of gray wolves that occurred between 20,000 and 40,000 years ago.
Dogs were the first animal to be domesticated by humans. The oldest dog fossils that can be clearly distinguished from wolves are from the region of what is now Germany from around 15,000 years ago. However, the archeological record is ambiguous, with claims of ancient domesticated dog bones as far east as Siberia. Recent analysis of genetic data from modern dogs adds to mystery, with some scientists suggesting many areas of Europe, Central Asia, South Asia and the Middle East as possible origins of dog domestication.
In 2016, research by scientists using emerging paleogenomics techniques proved effective for sequencing the genome of a 5,000-year-old ancient dog from Ireland. The results of the study led the research team to suggest dogs were domesticated not once but twice. The team from Oxford University also hypothesized that an indigenous dog population domesticated in Europe was replaced by incoming migrants domesticated independently in East Asia sometime during the Neolithic era.
“Contrary to the results of this previous analysis, we found that our ancient dogs from the same time period were very similar to modern European dogs, including the majority of breed dogs people keep as pets,” explained Dr. Veeramah. “This suggests that there was no mass Neolithic replacement that occurred on the continent and that there was likely only a single domestication event for the dogs observed in the fossil record from the Stone Age and that we also see and live with today.”
In the paper, titled “Ancient European dog genomes reveal continuity since the Early Neolithic,” Veeramah and colleagues used the older 7,000 year old dog to narrow the timing of dog domestication to the 20,000 to 40,000 years ago range.
They also found evidence of the younger 5,000 year old dog to be a mixture of European dogs and something that resembles current central Asian/Indian dogs. This finding may reflect that people moving into Europe from the Asian Steppes at the beginning of the Bronze Age brought their own dogs with them.
“We also reanalyzed the ancient Irish dog genome alongside our German dog genomes and believe we found a number of technical errors in the previous analysis that likely led those scientists to incorrectly make the conclusion of a dual domestication event,” added Veeramah.
Overall, he emphasized, their new genomic analysis of ancient dogs will help scientists better understand the process of dog evolution, even if the exact geographic origin of domestication remains a mystery. He expects further sequencing of the ancient genomes from Eurasia will help to eventually solve the issue.
The study and findings are a collaboration between scientists at Stony Brook University; the University of Michigan, Johannes Gutenberg-University, Germany; University of Bamberg, Germany; Trinity College, Ireland; and the Department of Monumental Heritage in Germany.
The research was supported in part by the National Institutes of Health.
About Stony Brook University Stony Brook University is going beyond the expectations of what today’s public universities can accomplish. Since its founding in 1957, this young university has grown to become one of only four University Center campuses in the State University of New York (SUNY) system with more than 25,700 students, 2,500 faculty members, and 18 NCAA Division I athletic programs. Our faculty have earned numerous prestigious awards, including the Nobel Prize, Pulitzer Prize, Indianapolis Prize for animal conservation, Abel Prize and the inaugural Breakthrough Prize in Mathematics. The University offers students an elite education with an outstanding return on investment: U.S. News & World Report ranks Stony Brook among the top 40 public universities in the nation. Its membership in the Association of American Universities (AAU) places Stony Brook among the top 62 research institutions in North America. As part of the management team of Brookhaven National Laboratory, the University joins a prestigious group of universities that have a role in running federal R&D labs. Stony Brook University is a driving force in the region’s economy, generating nearly 60,000 jobs and an annual economic impact of $4.65 billion. Our state, country and world demand ambitious ideas, imaginative solutions and exceptional leadership to forge a better future for all. The students, alumni, researchers and faculty of Stony Brook University are prepared to meet this challenge.
Even better than the University providing the link to the above, it also gave me the good Doctor’s email address. I shall reach out to him and see if there is more that I can share with you!