Being able to socialise effectively with humans was crucial for proper cooperation. Unable to speak a common language, dogs instead developed other capacities to best live alongside them. Among humans, the ability to gaze into each other’s eyes and respond accordingly to the other’s gaze is an important factor of social bonding. Thus, over time, dogs developed their visual cognitive ability to also be able to communicate with humans via a gaze, much how infants are able to communicate with adults via eye contact (Nagasawa: 2009).
Previous research has suggested that human-dog companionship lies in wolves’ abilities to identify gestures and vocal patterns in our ancestors (Makhijani: 2017). Although there may be some validity in this theory, there is now genetic evidence suggesting that the first wolves who ventured to early settlements were instead selected for their tendency to seek human companionship (Lennon: 2019).
Although eye contact is important, studies have shown that humans are able to connect with animals is dependent on an expression of human-like features, even if the object is not human. For example, the fact that humans tend to find paedomorphic, or babyish, physical traits cute has encouraged the flourishing of some physical traits among dogs.
Such adaptive changes are not exclusive to dogs. A study of spanning 45 years of fox kits selectively bred to approach humans fearlessly and non aggressively showed some similar results. The results found that domesticated foxes were as skilled as domestic dogs in using human communicative gestures to find food. Although the domesticated foxes were no more likely than wild foxes to approach an unknown human or novel object, they tended to approach them more quickly. Taken with the gradual evolution of wolves to dogs, these findings suggest the occurrence of sociocognitive evolution as a by-product of a reduced need for fear and aggression (Hare: 2005).
Wolves and dogs share 99.9% of their DNA. Technically still the same species, they can also produce healthy offspring. But having said that, there’s no denying the physical difference between wolves and dog breeds such as chihuahuas and dachshunds. So in this case, how did wolves become dogs? What makes this 0.1% genetic difference?
Germonpré suspects that the apparent domestication at Pˇredmostí was a dead-end event; she doubts that these animals are related to todays dogs. Nevertheless, to Germonpré, “they are dogs—Paleolithic dogs.” She says these early dogs probably looked very much like todays huskies, although they would have been larger, about the size of a German shepherd. Germonpré calls the Pˇredmostí specimens “dogs” because of what she interprets as some type of relationship between the canids and the Gravettians. For instance, a dogs lower jaw was found near a childs skeleton, according to the diary of the original excavator.
And that finding leads back to the questions Virányi and most everyone who owns and loves a dog has: How did these hunter-gatherers do it? Or did they? What if the first dogs—which, it is important to remember, would have at first been more wolf than dog—showed up on their own?
“Dog burials happen after hunting moves away from the open plains and into dense forests,” says Angela Perri, a zooarchaeologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and a specialist on these burials. “Dogs in open environments might be good for helping you transport meat from killed mammoths but wouldnt necessarily help you hunt them,” she says, noting that elephant hunters do not use dogs. “But dogs are excellent for hunting smaller game, such as deer and boar,” that live in forests.
As inscrutable as the mystery is, scientists are piecing it together. In the past few years they have made several breakthroughs. They can now say with confidence that contrary to received wisdom, dogs are not descended from the gray wolf species that persists today across much of the Northern Hemisphere, from Alaska to Siberia to Saudi Arabia, but from an unknown and extinct wolf. They are also certain that this domestication event took place while humans were still hunter-gatherers and not after they became agriculturalists, as some investigators had proposed.
“You can leave a piece of meat on a table and tell one of our dogs, No! and he will not take it,” Virányi says. “But the wolves ignore you. Theyll look you in the eye and grab the meat”—a disconcerting assertiveness that she has experienced on more than one occasion. And when this happens, she wonders yet again how the wolf ever became the domesticated dog.
Mitochondrial DNA is passed down by the mother (without any genetic contribution from the father) and changes only through random mutations that occur from generation to generation. Scientists use this much smaller and separate DNA sequence to estimate when populations of animals first diverged and to estimate the evolutionary relationships between organisms.
This similarity is so profound that hybridization often occurs between dogs and wolves. By the biological definition of species, this would mean that the domestic dog is a subspecies of the grey wolf (canis lupus familiaris). There remains some debate, however, as to what the appropriate classification for the domestic dog would be, with some arguing that the domestic dog should be its own distinct species (canis familiaris).
By the mid-2000s, new technology allowed scientists to map the much longer DNA sequence found on the chromosomes of wolves and dogs — the genes that actually code for physical traits and behaviors. These studies demonstrated a 99.9% similarity (technically 99.96%) between dog and grey wolf, as covered in a 2007 review paper on the topic:
The idea that the domestic dog descended from the grey wolf was originally established in 1993 using comparisons of wolf and dog mitochondrial DNA. This investigation showed that no other living animal was more closely related to the domestic dog than the grey wolf: “The domestic dog is an extremely close relative of the grey wolf, differing from it by at most 0.2% of [mitochondrial DNA].”
These advances in genetic analysis have allowed scientists as well to pin down the probable timing of the split between these two canid lineages. A study published in 2015, which compared the whole genome sequence of dogs to a 35,000 year old Siberian wolf specimen, suggested the split likely occurred between 27,000 and 40,000 years ago, and that domestic dogs are likely themselves the descendants of a now extinct descendant of grey wolves.
What’s the Differences Between Wolf vs Dog – Can Wolves Become Pets?
Megan Callahan-Beckel has been working with gray wolves since she was 4 years old. Now the animal care coordinator at the Wildlife Science Center in Minnesota—where her mother, Peggy Callahan, is the executive director—Callahan-Beckel grew up in a home inhabited by not only dogs but also wolf puppies, who must be intensively hand-reared for them to be comfortable with humans later in life. She now raises wolf puppies in her own home every summer, and they come to adore her and see her as a kind of mom.
Much as she loves the wolves, Callahan-Beckel is well equipped to explain why dogs live in our homes and wolves stick to the great outdoors. “They test you, they get into your face, they are cocky, they’re destructive,” she says. “They’re everything that people shouldn’t want in dogs.”
For scientists who want to understand how dogs came to be our constant companions, this contrast presents a promising path forward. While wolves and domestic dogs technically belong to the same species—they can interbreed and produce fertile offspring—their genomes hold meaningful differences. Unlike wolves, for example, dogs are omnivorous: Over the tens of thousands of years that dogs have lived alongside humans, they have evolved to produce larger amounts of an enzyme needed to digest carbohydrates. (House pets can lead long and healthy lives on a kibble diet.)
But the dog-human bond is more than a matter of a digestive protein—it comes down to behavior. “We’re interested in what makes dogs special,” says Clive Wynne, director of the Canine Science Collaboratory at Arizona State University. “How is it that dogs have the amazing role in our lives that they do, and that they have had for thousands of years? How do they pull that off?”
To answer this question, researchers can directly compare the behavior of dogs and wolves to figure out what has changed since their evolutionary divergence. Over five years of testing at the Wildlife Science Center, a team led by Brian Hare, director of the Duke Canine Cognition Center, managed to obtain behavioral data from 37 hand-reared wolf puppies—a far larger sample than anyone had previously tested. They compared the results from wolves with data from 44 dog puppies, who had been raised in litters and so had less human contact than many pet dogs do, and found that the dogs were much more interested in—and better at communicating with—people, despite their comparatively low level of human interaction. Their results were published in July in the journal Current Biology.
The dog and wolf puppies displayed their communication skills by completing a food-finding task with a human partner. The experimenter hid food in one of two bowls, and then pointed to the bowl with the snack or placed a colored block beside it. Unlike a dog who sits in response to a verbal command from its owner, these puppies had never been trained to use the nonverbal cues—the experiment was designed to get at their innate ability to respond to human gestures and signals. While the wolf puppies showed some limited ability to complete this pointing task, the dog puppies performed far better in both versions of the experiment. On both tests, the dogs chose the correct container more than three out of four times; the wolves’ success rate was closer to 60 percent.Most Popular
Researchers have known for a long time that dogs are particularly good at this pointing task. They even appear to be better at it than chimpanzees, who are otherwise thought to be substantially more intelligent. But this observation alone doesn’t necessarily explain what’s going on with dogs. Perhaps they spend more time around people and so learn more about human gestures, or perhaps their abilities have a genetic root.
Earlier this year, researchers found new support for this second idea when they measured the extent to which the ability to follow pointing gestures runs in dog families. Puppies who were more closely related to each other scored more similarly on the pointing test, which indicates that their scores could be partly explained by their genetics.
The ability of dogs to complete this task could be a product of domestication. Humans, intentionally or unintentionally, could have prompted dogs to become more effective communicators; people could have purposefully bred the friendliest dogs with each other, or, alternatively, the friendliest individuals could have been the most successful at living with humans. Or, the ability could be inherited from the common ancestor of dogs and modern-day wolves. To distinguish between these two possibilities, and to limit the influence of environmental factors, researchers have tried to compare dog and wolf puppies who were raised similarly. A 2008 study found that the dogs did better than the wolves on the pointing task, but a paper published the following year failed to replicate that difference.
This new study, which has a far larger sample size and compares wolves with more human contact to dogs with less contact, solidifies the conclusion that dogs are indeed better at this task than wolves, says Juliane Bräuer, head of the DogStudies Lab at the Max Planck Institute for the Science of Human History. “It was quite a big sample size, especially for the wolves,” she says. “To find testable wolves is always a challenge.”
Dogs’ abilities to follow pointing cues, then, appear to be a product of domestication—there’s an important genetic difference between dogs and wolves at work here. But just where genetics enters the picture remains an open question. Hare thinks that the key element is an evolved reduction in the natural fear that wolves have toward humans. (“Wolves are giant wusses,” Callahan-Beckel says.) As pack hunters, wolves need to be capable of coordinating with other members of their species. Hare believes that, during the process of domestication, dogs expanded their potential set of coordination partners to include people. “Dogs inherited a skill set at understanding others from wolves,” he says. “When fear was replaced by an attraction, those skills became enhanced.”
But perhaps dogs are simply more inclined to learn from humans, and do so incredibly quickly. In support of this second possibility, Wynne notes that the older dog puppies in the study performed better on the pointing task than the younger ones, which suggests that some learning was taking place.Most Popular
In general, Wynne finds it difficult to believe that dogs have an ingrained ability to understand human gestures or human intentions. “It’s just absurdly unlikely that dogs could be born with an innate ability to follow human pointing gestures, when our own children are not born with an ability to follow human pointing gestures,” he says.
Both Hare and Wynne agree, however, that there is one major, striking difference between dogs and wolves, regardless of how they are raised: Dogs are far, far more attracted to humans. The wolves that Callahan-Beckel and Callahan raise will often, as adults, let their rearers rub their bellies and scratch them behind the ears. Strange humans, however, are a different story. In the study, dog puppies were 30 times more likely to touch unfamiliar humans than wolf puppies were.
Some wolves will see Callahan-Beckel and Callahan as their moms for life and greet them the way a pet dog might greet its owner arriving home from work. But others reveal their genetic history when they ultimately come to view their rearers as a leader to be overthrown. This happened recently for Callahan-Beckel, when Adam, a wolf she had raised, became the leader of his pack—and then decided he was the boss of her as well.
“I still love Adam. I still love him so much,” Callahan-Beckel says. “And I walk up to the fence [saying], ‘Oh, Adam, that’s my good boy,’ and he hits the fence as hard as he can, roaring, with his tail up, trying to kill me. And it’s just the way they are.”More Great WIRED Stories