New Study Suggests that Man and Dog Have Been Close Friends for 33,000 Years

New Study Suggests that Man and Dog Have Been Close Friends for 33,000 Years

A new study reveals that the origin of man’s best friend may not have been where, or when, the scientific community previously believed. The analysis of a variety of ancient canine DNA has also helped researchers create a map of the journey of the domestic dog across the world.

This is believed to be the most complete study of dog genomes to date, and as the researchers wrote in their article published online in the journal Cell Research , “For the first time, our study unravels an extraordinary journey that the domestic dog has traveled on earth.”

Peter Savolainen of Sweden's KTH Royal Institute of Technology, and one of the contributors to the current study’s international team, told Phys.org that while past studies also analyzed the entire nuclear genome, they failed to include samples from South East Asia – following the general belief that domesticated dogs had originated in the Middle East, Central Asia, or Europe.

This time the researchers conducted a DNA analysis using samples from more regions of the world and different time periods. They used this information to look for series of admixtures (events that occur when individuals from two or more separate species begin to interbreed). The results of their study have led them to assert that domesticated dogs most likely descended from gray wolves in South East Asia, about 33,000 years ago. Furthermore, they claim that the “founder population” numbered approximately 4,600 canines.

A gray wolf. ( Gunner Ries/CC BY SA 3.0 )

The sample was composed of genomes from 58 canids. Specifically, the scientists analyzed DNA from:

“Dogs from Central Asia (Afghan Hound) and North Africa (Sloughi), Europe (eight different breeds), the Arctic and Siberia (Greenland dog, Alaska Malamute, Samoyed, Siberian Husky, and East Siberian Laika), the New World (Chihuahua, Mexican and Peruvian naked dog) as well as the Tibetan Plateau (Tibetan Mastiff). These dogs were chosen to cover as many major geographic regions as possible.”

Geographic locations of the 58 canids sequenced in the study. (Guo-Dong Wang, et. al )

Through their research, they have also provided an explanation for the migration of the domesticated dogs to the rest of the world:

“Around 15,000 years ago, a subset of ancestral dogs started migrating to the Middle East, Africa and Europe, arriving in Europe at about 10,000 years ago. One of the out-of-Asia lineages also migrated back to the east, creating a series of admixed populations with the endemic Asian lineages in northern China before migrating to the New World.”

Three of the dog breeds that were chosen for the DNA study: Siberian Husky ( CC BY SA 3.0 ), Tibetan Mastiff ( CC BY SA 3.0 ), and Peruvian naked/hairless dog ( CC BY SA 3.0 )

The reasoning for the delay in migration may have been due to climatic conditions. Ya-Ping Zhang of the Chinese Academy of Sciences Kunming Institute of Zoology, and one of the co-authors of the current study told Discovery News : "For some reason, dogs stayed around East Asia for a long time before their migration out of Asia. We speculated that the glacial period might have been the environmental factor that prevented dogs from migrating out of Asia."

A proposed migratory history for domestic dogs across the world based on the evidence from the current study. Solid arrows show migratory tracts with complete dating information and dashed arrows indicate those without accurate dating. ( Guo-Dong Wang, et. al )

Although it is probable that the migration of dogs and humans were often interconnected, the recent study suggests that the first movement may have been chosen first by the canines, and not their human companions.

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As for the path to domestication, it has been said that the current research provides evidence for three main stages, instead of the former assumption of two: pre-domesticated scavengers that had loose contact with ancient humans, then closer human-dog interactions that led to domesticated “non-breed dogs,” and finally human selection for specific traits in dogs – selecting and creating breeds.

Savolainen told The Telegraph that the domestication process was not quick, and that it could have been created by “[…] waves of selection for phenotypes (mutations) that gradually favored stronger bonding with humans, a process called self-domestication.”

A German Shepherd dog. The German Shepherd is a relatively new breed of dog, that is often prized for its strength, intelligence, trainability, and obedience.

While the results of the current study are intriguing, the debate still continues on the origins of man’s best friend - a 2011 study of a 33,000-year-old skull of a partly domesticated dog found in a cave of the Altai Mountains of Siberia have led scientists to that area. However, the high genetic diversity of canines in Central Asia, as reported in a study released in October, has suggested Nepal or Mongolia for the beginnings for humanity’s loyal companion.

Additionally, analysis of an ancient wolf’s bones (also from Siberia), published in May state that the genetic split from wolves to dogs began sometime between 27,0000 – 40,000 years ago - although the scientists from this study acknowledged that these wolf-dog hybrids may not have been domesticated until later.

A Collage of dogs. Source: Томасина/CC BY 2.5

Featured Image: A Tamaskan dog. Tamaskan have wolf-like appearances.

By: Alicia McDermott


Study: Dogs Evolved to Use Eyes to Connect with Humans

Dog lovers are well aware of the ability of a dog to communicate with its eyes. Now, scientific research suggests this ability developed over time as dogs learned to live with humans.

Just like humans, the eyes can be one of the most appealing things about dogs, the animals known in many cultures as “man’s best friend.”

But a new study found evidence that dogs developed in physical ways to present “puppy dog eyes” as a way to help connect with humans. Researchers in Britain and the United States did the study. Results were published in the Proceedings of the National Academy of Sciences (PNAS).

The study compared the facial muscles of dogs and wolves, which share ancestral history. Dogs broke off from wolves after being domesticated about 33,000 years ago. During that time, dogs changed physically and behaviorally to fit life with humans.

The researchers examined the heads of six dogs and two wolves for comparison. They found the facial structure of both animals was mostly very similar. But one major difference was found above the eyes.

The dogs were found to have two well-formed muscles around the eye that were not present in the wolves. These small muscles permit dogs to “intensely” raise their inner eyebrow, the study found.

Anne Burrows is a professor at Duquesne University in Pittsburgh, Pennsylvania. She was a lead researcher on the study. “You don’t typically see such muscle differences in species that are closely related,” she told the Associated Press.

Comparative psychologist Juliane Kaminski from Britain’s University of Portsmouth led the research. The team suggests this eyebrow-raising movement causes “a nurturing” feeling in humans because it makes the dogs’ eyes appear larger.

This expression also makes the dog look more like a human baby. The eye movement is similar to that which humans make when they are sad, the statement said. “The evidence is compelling that dogs developed a muscle to raise the inner eyebrow after they were domesticated from wolves,” Kaminski said.

In a separate part of the study, the researchers observed how 27 dogs and nine wolves interacted with a human. “We also studied dogs’ and wolves’ behavior. And when exposed to a human for two minutes, dogs raised their inner eyebrows more and at higher intensities than wolves,” Kaminski said.

The researchers suggest that the eye movements developed over time as a way for dogs to get humans to do things for them. This could involve humans giving them food, care or attention.

Brian Hare, from America’s Duke University, edited the study. He called the findings “profound” for showing that these muscles likely developed to help in their interactions with people. “The proof has been in their puppy dog eyes all this time,” Hare said.

The only dog species in the study that did not have the muscles was the Siberian husky, which is an ancient kind. The husky could be the best living example of what the link between dogs and wolves looked like.

Anne Burrows said the main limitation of the study was the small number of dogs and wolves used. This means further study will be required and should include other ancient dog breeds. The work could also be extended to other animals with which humans have developed close relationships, including horses and cats, Burrows said.

Bryan Lynn wrote this story for VOA Learning English, based on reports from PNAS, the University of Portsmouth, the Associated Press and Agence France-Press. Caty Weaver was the editor.

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Humans and dogs first became best friends 30,000 years ago, claim scientists

And according to scientists, the relationship between dogs and humans could have endured for tens of thousands of years.

New research has found that the close bond started in Ice Age Europe between 19,000 and 30,000 years ago.

That was when wolves, ancestors of domestic dogs living today, were first tamed by ancient hunter gatherers, according to new genetic evidence.

The findings challenge a previous theory that dog domestication happened some 15,000 years ago in eastern Asia, after the introduction of agriculture.

In reality, the history of the bond between dog and man appears to go back much further, to a time when fur-clad humans were living in caves and hunting woolly mammoths.

Scientists used a tried and trusted technique of DNA analysis to establish what populations of wolves were most related to living dogs.

DNA from domestic dogs most closely matched that extracted from the fossil bones of ancient European Ice Age wolves, as well as modern wolves.

There was little similarity with DNA from wolves, coyotes and dingos from other parts of the world.

Early tamed wolves may have been trained as hunting dogs or even protected their human masters from predators, the researchers believe.

The Finnish and German team wrote in the journal Science: "Conceivably, proto-dogs might have taken advantage of carcasses left on site by early hunters, assisted in the capture of prey, or provided defence from large competing predators at kills."

Dog domestication of a "large and dangerous carnivore" was likely to have occurred partly by accident, possibly after wolves were attracted to hunter camp sites by the smell of fresh meat.

The research contradicts previous thinking that early farming brought wolves sniffing around villages, leading to them forming relationships with humans.

"Dogs were our companions long before we kept goats, sheep or cattle," said Professor Johannes Krause, one of the researchers from Tubingen University in Germany.

The scientists analysed a particular type of DNA found in mitochondria, tiny power stations within cells that generate energy.

Unlike nuclear DNA found in the hearts of cells, mitochondrial DNA is only inherited from mothers. This makes it a powerful tool in tracing ancestry.

The study included genetic data on 18 prehistoric wolves and other dog-like animals, as well as 77 dogs and 49 wolves from the present day.

Among the prehistoric remains were two sets of German dog fossils, one from a 14,700-year-old human burial site near Bonn, and the other dating back 12,500 years from a cave near Mechernich.

Most of the DNA from modern dogs was traceable to just one lineage, closely related to that of a wolf skeleton found in a cave in northern Switzerland.

"I was amazed how clearly they showed that all dogs living today go back to four genetic lineages, all of which originate in Europe," said study leader Olaf Thalmann, from the University of Turku in Finland.


New Study Looks at Why Neolithic Humans Buried Their Dogs With Them 4,000 Years Ago

Humans have enjoyed a long history of canine companions. Even if it's unclear exactly when dogs were first domesticated (and it may have happened more than once), archaeology offers some clues as to the nature of their relationship with humans.

Related Content

The latest clue suggests that humans living in Southern Europe between 3,600 to 4,200 years ago cared for dogs enough to regularly share their gravesites with them. Barcelona-based researchers studied the remains of 26 dogs from four different archaeological sites on the northeastern Iberian Peninsula.

The dogs ranged in age from one month to six years old. Nearly all were buried in graves with or nearby humans. "The fact that these were buried near humans suggests there was an intention and a direct relation with death and the funerary ritual, says lead author Silvia Albizuri, a zooarchaeologist with the University of Barcelona, in a press release.

To better understand the dogs' relationship with the humans they joined in the grave, Albizuri and her colleagues analyzed isotopes in the bones. Studying isotopes—variants of the same chemical element with different numbers of neutrons, one of the building blocks of atoms—can reveal clues about diet because molecules from plants and animals come with different ratios of various isotopes. The analysis showed that very few of the dogs ate primarily meat-based diets. Most enjoyed a diet similar to humans, consuming grains like wheat as well as animal protein. Only in two puppies and two adult dogs did the samples suggest the diet was mainly vegetarian.

This indicates that the dogs lived on food fed to them by humans, the team reports in the Journal of Archaeological Science. "These data show a close coexistence between dogs and humans, and probably, a specific preparation of their nutrition, which is clear in the cases of a diet based on vegetables," says study co-author Eulàlia Subirà, a biological anthropologist at the Autonomous University of Barcelona.

Top: remains of a dog found at the archeological site called La Serreta. Bottom: drawing of dog skeleton found between human skeletons in the necropolis Bòbila Madurell. (UB-UAB)

The archaeological sites all belong to people of the Yamnaya Culture, or Pit Grave Culture. These nomadic people swept into Europe from the steppes north of the Black and Caspian Seas. They kept cattle for milk production and sheep and spoke a language that linguists suspect gave rise to most of the languages spoken today in Europe and Asia as far as northern India.

The buried dogs aren't the oldest found in a human grave. That distinction belongs to a puppy found in a 14,000-year-old grave in modern-day Germany. The care given to that puppy to nurse it through illness was particularly intriguing to the researchers who discovered it. "At least some Paleolithic humans regarded some of their dogs not merely materialistically, in terms of their utilitarian value, but already had a strong emotional bond with these animals," Liane Giemsch, co-author on a paper about the discovery and curator at the Archäologisches Museum Frankfurt, told Mary Bates at National Geographic in 2018.

The fact that the researchers in the new study found so many dogs in the region they studied indicates that the practice of burying dogs with humans was common at the time, the late Copper Age through the early Bronze Age. Perhaps the canine companions helped herd or guard livestock. What is certain is that ancient humans found the animals to be important enough to stay close to even in death.

About Marissa Fessenden

Marissa Fessenden is a freelance science writer and artist who appreciates small things and wide open spaces.


Dogs' Closest Wolf Ancestors Went Extinct, DNA Study Shows

A new genetic analysis of modern dogs and wolves suggests that man's best friend was domesticated before agriculture.

But the origin of this domestication remains stubbornly mysterious. Researchers analyzed the genomes of wolves from three likely sites of domestication (the Middle East, Asia and eastern Europe), and found that modern dogs were not more closely related to any of the three. In fact, it seems that the closest wolf ancestors of today's dogs may have gone extinct, leaving no wild descendants.

"The dogs all form one group, and the wolves all form one group, and there's no wolf that these dogs are more closely related to of the three that we sampled," said study researcher John Novembre, a professor of genetics at the University of Chicago. "That's the big surprise of the study." [10 Things You Didn't Know About Dogs]

Domestication mystery

The origin of the domestic dog is a persistent mystery. Fossil evidence for domestication dates back as far as 33,000 years, based on the shape of the skull and on ancient DNA analysis. But the presence of a dog-like canine doesn’t prove the origin of modern dogs even if the fossil represents a domesticated dog, it could have been a failed lineage that left no descendants.

Researchers know that dogs regularly lived with humans by about 10,000 years ago, and dogs and people are found buried together as early as 14,000 years ago. Various genetic studies have pointed to China, the Middle East and Europe as the origin for today's domesticated dogs.

Novembre and his colleagues wanted to refine the understanding of domestication using high-quality, full genomes. They gathered full gene sequences from a wolf in Israel, a wolf in China and a wolf in Croatia to encompass the possible sites of the original dog domestication. Next, they also sequenced the full genomes of an Australian dingo, a feral dog species thought to have originated in Southeast Asia, and an African basenji. Neither of these dogs have territories that overlap with wolves, so researchers hoped they would see little of the post-domestication interbreeding that so often confuses the story of how dogs and wolves split.

The researchers also had a previously done full genome sequence for a Boxer.

Complicated canines

The high-quality, full sequences allowed the researchers to look at genetic variations across the entire genome. That's important, Novembre told LiveScience, because previous work was limited to snippets of DNA, chosen because they were known to vary from dog breed to dog breed. [The Coolest Animal Genomes]

"When we apply these to looking at dogs and wolves, we don't get a complete picture, because we can't see the variations that existed in wolves but vanished in dogs," Novembre said.

The new results, published today (Jan. 16) in the journal PLOS Genetics, reveal that dogs do not hail from the same lineage as modern wolves — a big surprise, said Novembre, who was hoping to see evidence for either a single domestication or multiple domestication events, where, for example, the Australian dingo would be most related to the Asian wolf and the African basenji would be most related to the Middle Eastern wolf.

Instead, the dogs are all most closely related to each other. The pattern suggests that dogs arose from a now-extinct line of wolves, Novembre said. Later, early in domesticated doggie history, they interbred with still-wild wolves, causing a genetic snarl that frustrates dog genetics researchers to this day.

The sequences also revealed that the first dogs arose from a very small number of the wolves that lived in their day, Novembre said. Around the time of domestication, both wolves and dogs experienced what's known as a population bottleneck — their numbers dropped. Genes can't explain why these drops occurred, Novembre said, but in the case of wolves, human encroachment and competition for large prey probably played a role.

Finally, the comparisons suggest that wolves and dogs split between 9,000 and 34,000 years ago, with a likely interval being between 11,000 and 16,000 years ago, before the rise of agriculture. Those findings are in line with the fossil record, Novembre said.

Previous research had suggested that perhaps dog domestication got a push from a genetic mutation that made it easier for modern dogs' ancestors to digest starch — meaning they could scavenge from human garbage piles. The new study looked at that gene mutation and found that it certainly occurred, but likely after dogs were already domesticated. Dingos, for example, are unquestionably dogs and not wolves, but they have few copies of the starch-friendly gene.

"You had domestication occurring in the context of dogs hanging around human hunter-gatherer groups, and only later, when these groups began to switch to farming, did they change their diets," Novembre said.

More answers coming?

However, there are still many questions left to answer. The reason for such a wide range of 25,000 years for the origin of domestication is that researchers had to base the estimate on rates of mutation in the genome. Mutations are rare, Novembre said, and estimating how often they happen is a tricky proposition. The best way is to compare the genomes of parents and offspring, but that work has not yet been done with dogs. Once it's done, Novembre said, the team will be able to refine its estimates.

However, the discovery that modern wolves and modern dogs seem to be more like sister groups than ancestors and descendants means that modern DNA sequences likely won't reveal the origin of domestication. To answer that question, Novembre said, ancient DNA analyses will be necessary.

So far, DNA sequences extracted from fossils are incomplete. But just as researchers have now sequenced a complete Neanderthal genome, they're on the cusp of sequencing full genomes from fossil dogs and wolves.

"Several groups are hammering away" at the problem, Novembre said, adding that a full ancient dog genome could be as few as nine months away.


Were Israel’s Canaan dogs man’s best friends 9,000 years ago?

Amanda Borschel-Dan is The Times of Israel's Jewish World and Archaeology editor.

Saudi Arabia and Israel may not have formal diplomatic relations today, but some 9,000 years ago there was evidently an open border policy — at least for Israel’s national breed, the Canaan dog.

Hundreds of massive petroglyphs were recently found on huge ruddy rocks in Saudi Arabia’s arid Shuwaymis and Jubbah regions that depict what appear to be Canaan dogs. The earliest depictions of dogs in the archaeological record, they show detailed snapshots of the canines — sometimes leashed — in vivid hunting scenes.

A study, “Pre-Neolithic evidence for dog-assisted hunting strategies in Arabia,” was recently published in the Journal of Anthropological Archaeology. Written by Maria Guagnina, Angela R. Perrib, and Michael D. Petraglia, it gives insight into early hunting strategies in which man’s best friend is thought to have been trained to run down its prey and tire it before a fatal blow is delivered — by dog fangs, or man’s spears and arrows.

In Saudi Arabia, Shuwaymis is located on the northern edge of lava fields in a wadi that is flanked with sandstone escarpments. Even 9,000 years ago, habitation would have been a challenge. Jubbah, on the other hand, is marked by paleolakes and the types of animal depictions point to a humid, slightly cooler climate for this time.

“The hunting dog depictions at Shuwaymis and Jubbah represent the earliest evidence of dogs on the Arabian Peninsula, predating the first faunal evidence of dogs by thousands of years,” according to the study.

Prior to this new Saudi find, the earliest images of dogs were uncovered on pottery shards in Iran dated to around 6,000 BCE. Paintings of Canaan dogs were also found in Egypt’s Beni-Hassan temple from circa 2,200 BCE.

What is unprecedented in many of the new Saudi scenes is that the dogs appear to be leashed to the hunters. “The leashes appear to be tethered to the waist of the hunters, leaving their hands free for the bow and arrow. Some hunters have an individual dog leashed to them and others have multiple,” write the authors.

These tethers, the scientists claim, demonstrate “how early Holocene hunters controlled their dogs, potentially utilizing different dogs for different tasks.”

“This suggests complex dog-assisted hunting strategies on the Arabian Peninsula began in the Pre-Neolithic,” reads the study. “Dogs may be leashed to, for example, protect valuable scent dogs from being injured or to keep dogs near a hunter for protection. They may also represent young dogs being trained to hunt or older dogs more susceptible to injury.”

Foremost Canaan dog expert Myrna Shiboleth is skeptical that hunters 9,000 years ago were able to “control” their dogs.

“Complex hunting strategies?” wondered Shiboleth, the author of “The Israel Canaan Dog,” quoting the recent study in an email to The Times of Israel this week. “I don’t think they had any idea of complex dog training. [The hunters] made use of the natural instincts of the dogs to hunt, and turned them loose to hunt and catch game or to track and find game, and they followed.”

Shiboleth concurred that the use of leashes would have increased the hunters’ control over their four-legged hunting friends.

“Dogs are not robots, they are dogs. Just as you can’t depend on a small child to always listen to what you tell him, the same is true of a dog, and if you want to keep him from interfering at some point in the hunt or whatever, you would keep him leashed,” she wrote.

There are only between 2,000-5,000 purebred Canaan dogs in the world today, with approximately 1,000 in Israel. However, most of the country’s wild dogs, and the majority of the dogs found in shelters are mixed with the breed.

The Canaan dog was first recognized in Israel as a registered breed in 1965 the American Kennel Society followed suit in 1997. According to the AKS, it has few genetic or health problems and its breed standards include easy training, alertness, vigilance, devotion and docility with family, but reservation and aloofness with strangers. It is characterized as being highly territorial, very vocal, and can suffer from shyness or dominance toward people.

All of the hundreds of etched dogs found in the two Saudi sites, write the study’s authors, “display characteristic pricked ears, short snouts, deeply-angled chests, and a curled tail, appearing to be of the same ‘type.'” … We suggest these canids bear a close resemblance to the modern Canaan dog,” write the authors.

In previous conversations with The Times of Israel, Shiboleth has described the Canaan breed as being more in a partnership with humans, rather than in a typical master-servant relationship.

“Put it this way: If you go to the edge of a cliff with a German shepherd and tell it to jump, it’ll jump. If you go to the edge of a cliff with a Canaan dog and tell it to jump, it’ll turn to you and say, ‘You first,'” she said.

Where are the Canaan dogs from and how did they get there?

The scientists are not certain whether the petroglyphs depict Canaan dogs originating in the Levant. There is also the possibility that the dogs depicted in the petroglyphs are ancestors to the modern Canaan breed, but originated in Arabia and moved to Israel at a later period and not vice versa, write the authors.

“It is unclear if the Shuwaymis and Jubbah dog depictions represent non-local dogs (e.g., from the Levant) or a localized domestication on the Arabian Peninsula,” write the authors of the Journal of Anthropological Archaeology study.

“The Arabian Peninsula dog depictions and modern Canaan dogs may represent a case of convergent evolution or two unrelated groups of dogs adapted to harsh, arid environments,” suggests the study.

According to a 2015 Nature article, dogs were first domesticated in southern East Asia 33,000 years ago. A fossilized skull of one semi-domesticated pet dog was found in Russia in 2011.

“We find that dogs from southern East Asia have significantly higher genetic diversity compared to other populations, and are the most basal group relating to gray wolves, indicating an ancient origin of domestic dogs in southern East Asia 33,000 years ago. Around 15,000 years ago, a subset of ancestral dogs started migrating to the Middle East, Africa and Europe, arriving in Europe at about 10,000 years ago,” according to the 2015 article.

A 1978 Nature article shows evidence for domestication of the dog 12,000 years ago in Israel. The Saudi rock carvings are dated to circa 9,000 years ago, which also is well after canine migration to the region.

A very unInstagram

The rock art would have taken considerable time to produce, say scientists.

“Chiseling stone is time-consuming and labor-intensive, so the effort would have had meaning behind it… Therefore, the subjects the artists deemed important enough to record in such a lasting medium are the very things that archaeologists consider to be of great interest,” according to the website, Arabian Rock Art Heritage, which provides information about a detailed project tasked with documenting the Saudi petroglyphs.

The petroglyphs found at Shuwaymis and Jubbah depict graphic scenes of canines locked in death grips on the necks of ibex and gazelle, which appear to often be nursing mothers or older stock. The scientists believe the dogs were also used for their ability to instinctually chose the easier prize.

What is clear is that the scenes are evocative.

“It’s a little bit heart wrenching, the equids are usually mothers with their young being attacked,” said Guagnin, who over the past three years has analyzed over 1,400 panels of petroglyphs, to The New York Times. “It’s quite interesting to see these scenes with the dying animals and there are dogs hanging off them.”

Gaugin shared the scenes with a colleague at the Max Planck Institute for the Science of Human History in Germany, Angela Perri, a zooarchaeologist.

“When Maria came to me with the rock art photos and asked me if they meant anything, I about lost my mind,” Perri told Science magazine. “A million bones won’t tell me what these images are telling me… It’s the closest thing you’re going to get to a YouTube video.”

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The Untold Story Of How Dogs Became Our Best Friends

Dogs and humans have been BFFs for a very long time -- at least 10,000 years.

But have you ever wondered just how dogs and other animals got domesticated, and why? And how today's domesticated animals differ from their wild predecessors? The story is even more complicated than you might imagine.

To learn more about how man's best friend came to be -- and how dogs changed the course of human history -- check out the video above, and/or read the transcript below.

Don't forget to leave your thoughts in the comments. Talk nerdy to me!

They’re our best friends! Around 144 million Americans own a dog or cat as a pet. But how did our domesticated companions make the transition from wild creatures to tamed animals? And what does their history have to do with our history? Let’s find out.

Hey everyone. Jacqueline Howard here. Evidence for animal domestication can be found in ancient texts, wall paintings, Egyptian tombs and burial grounds. From all of this evidence along with modern genetic testing, we can piece together a pretty good timeline as to what animals were domesticated and where and when this took place.

For instance, we know that dogs were humans’ first pets. Some scientists say they evolved from wolves, but a new study suggests that dogs and gray wolves rather evolved from a common ancestor. Regardless, archaeologists know, from digging up artifacts and animal bones, that dogs have been a part of human lives way before the advent of agriculture -- so at least 10,000 years ago. In fact, mummified dogs have been found in ancient tombs in Egypt.

So this evidence strongly suggests that we were still hunter-gatherers when the earliest dogs most likely arose, and they likely played a big role in protecting us. For instance, a dog’s barking could have been like a prehistoric alarm system letting us know when dangerous animals or other tribes of foragers were nearby.

Then, how did domestic dogs, which are all of the subspecies Canis lupus familiaris, grow and branch out into so many different breeds all around the world? Artificial selection. That means we humans, for thousands of years, selected the dogs we liked the most -- because of their fluffy fur or friendly personality or intelligence or even ferocity -- and we kept those dogs around, and we bred them. In a span of less than 10,000 years, breeders have changed dogs’ personality traits and body shapes so they’d have aspects that we preferred. For instance, a dog may have been bred for its hunting and herding behavior. See what I mean?

Some scientists say that as humans realized that we could domesticate and use dogs for everyday tasks, like hunting, we then started to domesticate other animals for various tasks and resources too -- like sheep, goats, cattle, and pigs.

The domestication of animals played a key role in the rise of agriculture, and the expansion of early civilizations around 10,000 years ago. Just think, domesticating work animals -- from cattle and oxen to dogs and cats -- creates larger farms, which thus means more food and more people. When the population in one area grows so does infrastructure, social hierarchies, monumental architecture, I could go on and on. Around this time, different civilizations also traded and used livestock like currency. Horses and camels became the go-to form of transportation to trek long-distance trade routes. These beasts of burden transformed our way of life.

Of course, the domesticated animals that impacted certain communities varied around the world. Cattle, oxen, sheep, goats, horses, donkeys, camels, chickens, and pigs were all native to Afro-Eurasia while the people of the Americas domesticated llamas, turkeys, and guinea pigs…not exactly animals that could pull heavy plows or take you on long-distance trip. Because you can’t ride a llama or turkey, there wasn’t much opportunity to travel long distances to trade and develop -- which sheds light on how and why the civilizations in the Americas took a bit longer to develop than those in Afro-Eurasia. So you see, fluffy had way more to do with the evolution of human civilization than you probably thought.


When did dogs become man's best friend?

Man's best friend may have been domesticated about 15,000 years ago, evolving from wolves around the time that humans were establishing their first settlements, new evidence suggests.

Using sophisticated 3D imaging to analyze several fossil skulls, a study in this week's Nature Scientific Reports found dogs emerged much more recently than previously thought. Other studies in recent years had suggested dogs evolved as early as 30,000 years ago, a period known as the late Paleolithic, when humans were hunter-gatherers.

Abby Grace Drake, a biologist at Skidmore College and one of the co-authors of the latest study, said there is an abundance of evidence -- including the skulls as well as genetic and cultural evidence -- to show dogs arrived instead in the more recent period known as the Neolithic.

"The dog remains from the Neolithic are found buried with humans and adorned with ornaments such as necklaces of deer teeth," Drake told CBS news in an interview.

"Whether dogs were domesticated in the Paleolithic or the Neolithic creates two different scenarios for how domestication may have taken place," she explained. "In the Paleolithic humans were hunter-gatherers. In the Neolithic is when we started to build permanent settlements that would have required 'dumps.' These piles of food and human waste would have attracted scavengers. Some scientists propose that wolves that scavenged at these dumps would have access to valuable food and those that could tolerate the presence of humans would be more successful."

The skulls of a German Shepherd and a Grey Wolf are put side by side to show their subtle differences

To come to this conclusion, Drake, along with Michael Coquerelle of the University Rey Juan Carlos and Guillaume Colombeau from the University of Bordeaux, reanalyzed two skulls as much as 32,000 years old from Russia and Belgium which had been identified as dogs. They used 3D technology to examine 36 points on the skull, including including the muzzle, palate, teeth, and braincase, as well as CT scans of the fossil skulls.

Then they compared those findings to the skulls of more than 100 other dog and wolves, including modern breeds.

The end result: those ancient skulls were from wolves, not dogs. Their findings called into question the theory that dogs had domesticated for 30,000 years.

"I have been using this 3D technique on dogs and wolves for my previous studies so I already had a very large database of skulls to compare the fossils to," Drake said. "Since I had this database I was curious as to how these early fossils would compare. Would they appear as primitive dogs? Dog-wolf hybrids? I was surprised when I discovered they were shaped like the wolf skulls."

Drake said this new 3D technique "allows us to test parts of the skull which were not measured before." The skulls had previously been only measured by caliper, which Drake said, "do not distinguish between dogs and wolves and miss important aspects of the skull such as the angle of the orbits and angle of the muzzle."

"The 3D technology captures these subtle shape changes very well," she said.

This is the latest chapter in a long-running debate over just when and where dogs were domesticated.

A 2013 study in PLOS One, looking at a different fossil skull found in the Altia Mountains of Siberia, concluded that dogs were domesticated 33,000 years ago. They based their findings on a genetic sequence from the skull compared with genetic sequences of 72 modern dogs from 70 breeds, 30 wolves, four coyotes and 35 prehistoric canid species from the Americas.

Armed with much more data, the researchers writing in Science later that year and using several of the same skulls concluded that dogs were domesticated in Europe about 18,000 to 32,000 years ago.

One of the authors on both studies, Olaf Thalmann of the University of Turku in Finland, responded to the new findings by saying that "every new measurement of the remains reveals a different story."

But while calling the study interesting, he remained unconvinced by the new evidence that dogs could have evolved as late as the Neolithic.

"I wonder, why Drake et al. argue that domestication must have happened later in time during the Neolithic instead of the late Pleistocene. The authors simply use a potential 'misclassification' of two samples to reject a hypothesis that has been supported by independent research before," he said in an e-mail to CBS News.

"At least a handful of genetic studies based on diverse markers (including complete genomes) has demonstrated that the onset of domestication must have occurred before at least 15,000 years ago," he said. "Aside from this genetic evidence I wonder, if the domestication originated in the Neolithic, say around 10,000 years, how would other fossils fit into the picture?" He cited the example of three specimens that appear to be much older.

Drake was confident in her findings, adding that several researchers had applauded their technique for bringing much greater accuracy to the work of assessing the skulls. But she admitted it by no means ends the debate on dog domestication -- noting that she had tried to test the Altia skull and was denied access by the scientists who said they are still examining it.

"Every time we find more fossil material, we will have test it with this new methodology," she said. "There also the fossil out there like the skull from Altai that we would also to examine to determine if it's a dog or wolf. We can't say unless we are able test it."


How dogs tracked their humans across the ancient world

Sometime toward the end of the last ice age, a gray wolf gingerly approached a human encampment. Those first tentative steps set his species on the path to a dramatic transformation: By at least 15,000 years ago, those wolves had become dogs, and neither they nor their human companions would ever be the same. But just how this relationship evolved over the ensuing millennia has been a mystery. Now, in the most comprehensive comparison yet of ancient dog and human DNA, scientists are starting to fill in some of the blanks, revealing where dogs and humans traveled together—and where they may have parted ways.

“It’s a really cool study,” says Wolfgang Haak, an archaeogeneticist at the Max Planck Institute for the Science of Human History. “We’re finally starting to see how the dog story and the human story match up.”

Dogs are one of the biggest enigmas of domestication. Despite decades of study, scientists still haven’t figured out when or where they arose, much less how or why it happened. A 2016 study concluded that dogs may have been domesticated twice, once in Asia and once in Europe or the Near East, but critics said there wasn’t enough evidence to be sure. A few years later, researchers reported signs of dogs in the Americas as early as 10,000 years ago, yet those canines appear to have vanished without a genetic trace. Other studies have found evidence of ancient dogs in Siberia and elsewhere, but scientists don’t know how they got there or how they’re related.

To fill in some of the blanks, two big names in dog and human genetics teamed up: Greger Larson, an evolutionary biologist at the University of Oxford, and Pontus Skoglund, a paleogenomicist at the Francis Crick Institute. Larsen, Skoglund, and colleagues sifted through more than 2000 sets of ancient dog remains dating back nearly 11,000 years from Europe, Siberia, and the Near East. In the process, they added 27 ancient dog genomes to the five already on record. They then compared those with the genomes of 17 humans living in the same places and times as the dogs.

The dog DNA alone revealed some surprises. As early as 11,000 years ago, there were already five distinct dog lineages these gave rise to canines in the Near East, northern Europe, Siberia, New Guinea, and the Americas, the team reports today in Science. Because dogs had already diversified so much by that time, “domestication had to occur long before then,” Skoglund says. That fits with archaeological evidence: The oldest definitive dog remains come from Germany about 15,000 to 16,000 years ago.

Remarkably, pieces of these ancient lineages are still present in today’s pooches. Chihuahuas can trace some of their ancestry to early American dogs, for example, whereas Huskies sport genetic signatures of ancient Siberian dogs, the team found. “If you see a bunch of different dogs in a dog park,” Skoglund says, “they may all have different ancestries that trace all the way back 11,000 years” (see figure below).

Today’s dogs can trace their ancestry to canines that lived up to 11,000 years ago.

When the researchers compared their dog DNA with modern and ancient wolf DNA, they got another surprise. Most domesticated animals pick up genetic material from their wild relatives—even after domestication—because the two species often live in close proximity and can still mate (think pigs and wild boars). But dogs show no such “gene flow” from wolves. Instead, the wolves gained new DNA from the dogs—a one-way street.

Larson chalks this up to the intimate relationship between dogs and humans. If your pig or chicken becomes a bit wilder thanks to an infusion of feral DNA, it doesn’t matter, because you’re going to eat them anyway, he explains. But dogs that go native make bad guards, hunting companions, and friends. “If you’re a dog and you have a bit of wolf in you, that’s terrible,” Larson says. People will “get rid of the dog.”

The wolf-dog analysis also suggests dogs evolved only once, from a now-extinct wolf population. Still, Larson, who led the 2016 study on multiple domestication events, says more data are needed to seal the deal.

Then the scientists brought humans into the mix. They selected human DNA samples from the same places and eras for which they had ancient canine DNA, and traced the genetic history of each. “It’s like you have an ancient text in two different languages, and you’re looking to see how both languages have changed over time,” Skoglund says.

In many places, the team found a strong overlap between human and dog genomes. For example, farmers and their pups in Sweden about 5000 years ago both trace their ancestry to the Near East. This suggests early farmers took their dogs with them as agriculture spread throughout the continent. “Writ large, as humans moved, they moved with their dogs,” Larson says.

But sometimes the stories didn’t match up. Farmers in Germany about 7000 years ago also came from the Near East and also lived with dogs. But those animals seem more similar to hunter-gatherer pups, which came from Siberia and Europe.

That suggests many early migrants adopted local dogs that were better adapted to their new environment, Haak says. The benefits were many, adds Peter Savolainen, a geneticist at the Royal Institute of Technology and an expert on dog origins. “They were cute. You could use them. You could even eat them.”

Savolainen calls the study “very thorough,” and adds it’s “fantastic” that the researchers were able to bring together so many data. But he has long argued that dogs arose in Southeast Asia and says the work is incomplete without samples from that corner of the globe. “Without those, you could be missing an important part of the picture.”

For now, Larson says his team is analyzing “a ton” of wolf and dog genomes. He and his colleagues have also begun to look at ancient skull shape and genetic markers that could give clues to what early dogs looked like. Whatever he finds, he’s counting on being surprised. “We have to expect the unexpected,” he says, “because that’s all ancient DNA ever gives us.”


Dogs' Closest Wolf Ancestors Went Extinct, Study Suggests

A new genetic analysis of modern dogs and wolves suggests that man's best friend was domesticated before agriculture.

But the origin of this domestication remains stubbornly mysterious. Researchers analyzed the genomes of wolves from three likely sites of domestication (the Middle East, Asia and eastern Europe), and found that modern dogs were not more closely related to any of the three. In fact, it seems that the closest wolf ancestors of today's dogs may have gone extinct, leaving no wild descendants.

"The dogs all form one group, and the wolves all form one group, and there's no wolf that these dogs are more closely related to of the three that we sampled," said study researcher John Novembre, a professor of genetics at the University of Chicago. "That's the big surprise of the study." [10 Things You Didn't Know About Dogs]

Domestication mystery

The origin of the domestic dog is a persistent mystery. Fossil evidence for domestication dates back as far as 33,000 years, based on the shape of the skull and on ancient DNA analysis. But the presence of a dog-like canine doesn&rsquot prove the origin of modern dogs even if the fossil represents a domesticated dog, it could have been a failed lineage that left no descendants.

Researchers know that dogs regularly lived with humans by about 10,000 years ago, and dogs and people are found buried together as early as 14,000 years ago. Various genetic studies have pointed to China, the Middle East and Europe as the origin for today's domesticated dogs.

Novembre and his colleagues wanted to refine the understanding of domestication using high-quality, full genomes. They gathered full gene sequences from a wolf in Israel, a wolf in China and a wolf in Croatia to encompass the possible sites of the original dog domestication. Next, they also sequenced the full genomes of an Australian dingo, a feral dog species thought to have originated in Southeast Asia, and an African basenji. Neither of these dogs have territories that overlap with wolves, so researchers hoped they would see little of the post-domestication interbreeding that so often confuses the story of how dogs and wolves split.

The researchers also had a previously done full genome sequence for a Boxer.

Complicated canines

The high-quality, full sequences allowed the researchers to look at genetic variations across the entire genome. That's important, Novembre told LiveScience, because previous work was limited to snippets of DNA, chosen because they were known to vary from dog breed to dog breed. [The Coolest Animal Genomes]

"When we apply these to looking at dogs and wolves, we don't get a complete picture, because we can't see the variations that existed in wolves but vanished in dogs," Novembre said.

The new results, published today (Jan. 16) in the journal PLOS Genetics, reveal that dogs do not hail from the same lineage as modern wolves &mdash a big surprise, said Novembre, who was hoping to see evidence for either a single domestication or multiple domestication events, where, for example, the Australian dingo would be most related to the Asian wolf and the African basenji would be most related to the Middle Eastern wolf.

Instead, the dogs are all most closely related to each other. The pattern suggests that dogs arose from a now-extinct line of wolves, Novembre said. Later, early in domesticated doggie history, they interbred with still-wild wolves, causing a genetic snarl that frustrates dog genetics researchers to this day.

The sequences also revealed that the first dogs arose from a very small number of the wolves that lived in their day, Novembre said. Around the time of domestication, both wolves and dogs experienced what's known as a population bottleneck &mdash their numbers dropped. Genes can't explain why these drops occurred, Novembre said, but in the case of wolves, human encroachment and competition for large prey probably played a role.

Finally, the comparisons suggest that wolves and dogs split between 9,000 and 34,000 years ago, with a likely interval being between 11,000 and 16,000 years ago, before the rise of agriculture. Those findings are in line with the fossil record, Novembre said.

Previous research had suggested that perhaps dog domestication got a push from a genetic mutation that made it easier for modern dogs' ancestors to digest starch &mdash meaning they could scavenge from human garbage piles. The new study looked at that gene mutation and found that it certainly occurred, but likely after dogs were already domesticated. Dingos, for example, are unquestionably dogs and not wolves, but they have few copies of the starch-friendly gene.

"You had domestication occurring in the context of dogs hanging around human hunter-gatherer groups, and only later, when these groups began to switch to farming, did they change their diets," Novembre said.

More answers coming?

However, there are still many questions left to answer. The reason for such a wide range of 25,000 years for the origin of domestication is that researchers had to base the estimate on rates of mutation in the genome. Mutations are rare, Novembre said, and estimating how often they happen is a tricky proposition. The best way is to compare the genomes of parents and offspring, but that work has not yet been done with dogs. Once it's done, Novembre said, the team will be able to refine its estimates.

However, the discovery that modern wolves and modern dogs seem to be more like sister groups than ancestors and descendants means that modern DNA sequences likely won't reveal the origin of domestication. To answer that question, Novembre said, ancient DNA analyses will be necessary.

So far, DNA sequences extracted from fossils are incomplete. But just as researchers have now sequenced a complete Neanderthal genome, they're on the cusp of sequencing full genomes from fossil dogs and wolves.

"Several groups are hammering away" at the problem, Novembre said, adding that a full ancient dog genome could be as few as nine months away.