Wolves and dogs are separated by 15,000 years of evolution, during which time the species have veered off into radically different directions. Dogs still retain many of their ancestral behaviors, but less is known about any latent “dog-like” tendencies among modern wolves. A new study of human-raised wolf pups suggests wolves can become attached to their owners in a manner reminiscent of dogs—but that’s where the similarities end.
New research published today in Royal Society Open Science shows that wolf puppies, when raised by humans, display signs of both attachment and affection towards their owners, and that these feelings last into adulthood. The study also shows that extensively socialized wolves are relatively comfortable around human strangers, though they sometimes exhibit a bit of fear. These findings hint at behaviors that may have led their four-legged ancestors to seek out and find comfort among humans, leading to the emergence of those super-cuddly, face-licking furballs known as dogs.
Before we get ahead of ourselves, it’s important to remember that wolves—even those raised by humans—are not dogs. Not by a long shot. This new study, which was led by Dorottya Ujfalussy from Eötvös Loránd University in Hungary, tells us something new about wolf behavior, specifically, that wolves can become attached to their human caregivers. It’s a finding that may prove significant when considering animal welfare and human safety issues faced by zoos and conservation areas. But what this study does not tell us is that humans should start raising wolf puppies. Wolves are still wild animals, and human environments are far removed from their natural habitats.
Indeed, wolves and dogs are two very distinct species. They may look similar (at least some dog breeds still look a bit wolf-like), but they exhibit profoundly different behaviors. Dogs have developed an intense and natural affinity towards humans, with brain scans suggesting they’re happier around us than they are around members of their own species. When stressed, dogs find comfort in the presence of humans—a trait that’s been reinforced through domestication. Wolves, on the other hand, are naturally wary of humans, fearing our presence and our environments. And unlike dogs, they’re fiercely independent. Wolf pups, for instance, are often left alone when the pack goes out to hunt, giving these animals an almost cat-like self-sufficiency. Unlike dogs, wolves have never had to lean on another species for support.
But scientists have also documented some behavioral similarities between dogs and wolves. When greeting each other, for instance, wolves like to lick each others’ faces—a trait that’s all too familiar to dog owners. Wolves are also capable of following a person’s gaze into space, and they understand gestures like finger pointing (not even chimps can do this).
Given these similarities, Ujfalussy sought to learn more about the kinds of relationship that wolves, when socialized to humans, can have with their human caretakers. A primary aim of the study was to figure out what makes dogs so unique in their relationship with humans, and where their traits may have originated. Ultimately, Ujfalussy was trying to learn if dog behaviors were already present in ancestral wolves, or if they’re a product of domestication and artificial selection. This new research suggests the former may be true.
Previous work had suggested that human-raised wolves, by the age of 16 weeks, don’t show any attachment to their caretakers as dogs do. This implied that only dogs are able to form a strong personal relationship to humans.
“We thought even at that time that the case is not that simple and wanted to describe the wolf-human relationship in more detail,” Ujfalussy explained to Gizmodo. “What we learned from our study is that while dogs may be more attached to their human caretaker in the sense of dependence and using their owners as a secure base, wolves are also able to form lasting affiliative relationships with their caretakers, though without a sense of dependence.”
To reach these conclusions, Ujfalussy’s team conducted experiments using wolf puppies raised by humans. (The experiments were conducted back in the early 2000s, but, due to the authors’ personal circumstances, the results are just being published now.) These wolves came from the Family Dog Project, an initiative founded in 1994 by József Topál and his colleagues to study the behavioral and cognitive aspects of the dog-human relationship. Over the years, this project has yielded over 100 publications in peer-reviewed journals. But for the purposes of this study, participants with the Family Dog Project were asked to raise wolf puppies—and in a way that was identical to how they would normally hand raise dogs (e.g. daily walks on leashes, cuddling, grooming, etc.). The wolf pups used in this study were socialized intensively to humans, making them ideal subjects for experiments to reveal any ‘inborn’ differences.
In the two experiments conducted, wolf puppies were put through a greeting test in which they were exposed to four visitor types: their immediate caregivers (or “foster-parents” as they’re called), close acquaintances, people they’ve met only once before, and complete strangers. In the first experiment, eight wolves were exposed to visitors when in the company of other wolves, but for the second experiment, nine wolf puppies had to go it alone.
“In our first experiment we opted for a group condition as we intended to keep the visits as stress free as possible for our subjects,” said Ujfalussy. “The presence of their pack mates gives social support. This was important especially in cases of stranger visits. However, in this situation the behaviour of [individual wolf pups were] not independent from the others, thus [making the] behaviour harder to interpret. For this reason we designed the second, individual experiment, at a later age, when wolves were more confident.”
In the first experiment, the wolf pups were six months old, and in the second experiment they were tested at 12 months and 24 months. To keep the interactions as consistent as possible, visitors were told to wear the same clothing, not wear any perfume or cologne, and not have anything in their pocket, along with a host of other control measures.
In both tests, the wolves approached visitors of all types readily and willingly. The six-month-old pups flocked to their human caregivers in an “intense and friendly” manner, and they were comfortable in the company of all visitor types. The 12-month-old and 24-month-old wolves likewise approached their foster-parents and close acquaintances with affection, but they were a bit apprehensive when approaching the other two visitor types. No aggressive behaviors were documented, but some of the wolf pups exhibited crouching and tail-tucking behaviors when approaching the strangers, which suggests they were a bit scared. Still, given that some of the wolves were as old as 24 months during the experiments, the results suggest that human-raised wolves will continue to seek contact with humans into early adulthood.
“To our knowledge, this study was the first to examine the relationship of intensively socialized hand reared wolves with humans varying in familiarity in a Greeting Situation Test,” says Ujfalussy.
“This result is exciting, not because wolves are more social than we thought, but because it is a step in uncovering the complexities of the differences between dogs and wolves in how they interact with humans,” said evolutionary biologist Kathyrn Lord, a postdoctoral associate in the Karlsson lab at the University of Massachusetts Medical School (who wasn’t involved in the study), in an email to Gizmodo. “Initially, it was supposed that wolves did not form social attachments with humans and dogs did, then it came out that we needed to look more closely at what was meant by attachment and we found that at least wolf pups did seem to have attachments with the people who socialized them. This paper supports those earlier findings that wolf pups do seem to form attachments and that while they are not dependent upon their caretakers later in life a social bond does seem to persist into adulthood.”
Still, it’s important that we greet these results with caution—it’s difficult to discern behavior from constrained experiments like these. The researchers did their best to minimize confounding factors, but that’s next to impossible; smells, body language, and other variables can interfere with results.
Also, there are limitations to studying wolves as precursors to dog behavior. Dogs are not descended from wolves (at least not modern wolves); both wolves and dogs split from a common ancestor around 15,000 years ago—an ancient animal whose behavior we’re not able to study.
Finally, the sample sizes weren’t great; a total of ten wolf pups were used in the study.
“Yes, indeed, our sample sizes are not huge,” Ujfalussy admitted to Gizmodo. “This is obviously because in Hungary (thankfully) wolves are relatively rarely born in captivity. Also, hand-rearing and individual socialization is a hard and trying job. And...these animals have to be taken care of for the rest of their lives, which is a challenge and a responsibility at the same time. For these reasons, we worked with the lowest possible sample size—data from which it’s still sufficient for statistical analysis.”
Jessica Hekman, a PhD Candidate at the University of Illinois at Urbana-Champaign and a veterinarian doing research in the genetics of dog behavior, isn’t surprised by these findings, and says this research jibes well with her own personal experience with wolves.
“I’ve been lucky to be able to spend time at Wolf Park, Indiana, where I saw wolves greeting familiar people,” Hekman, who wasn’t involved in the new study, told Gizmodo. “I saw one wolf greeting the man who had raised her, whom she hadn’t seen in months (a year, maybe). She was ecstatic to see him. I also saw wolves greeting their favorite human, who they saw probably about once a day or a little less at best guess, again clearly greeting him differently from others. I got to interact with them myself as a stranger, and they treated me very differently, much cooler.”
Hekman says the new study nicely mirrors her own field observations, showing that wolves respond differently to their caregivers than to other people. This finding is important, she says, because scientists are still trying to pick apart what the actual differences are between dog and wolf behavior. “Dogs bond tightly with humans, and as it turns out, wolves are capable of that too.”
One of the the more interesting findings, says Hekman, is that wolves do greet strangers, but still show fear-related behaviors.
“This study doesn’t compare these behaviors to how dogs greet strangers,” says Hekman. “My guess would be that there’s variation between individual dogs and individual wolves, but overall, that dogs show less fear of strangers than wolves do. The reduction of fear is thought to be a critical part of domestication.”
Obviously, this doesn’t mean we should brazenly approach wolves in the wild. Still, Ujfalussy says we have no reason to be wary or afraid of wild wolves, particularly if they’re given sufficient habitats, where they can live a natural life. Wild wolves under natural conditions avoid contact with humans, she says, and they have a good reason to do so.
“The problem starts when people disregard the advice of professionals and mistake wolves for dogs, keeping them as pets,” she says. “This is a serious welfare issue for wolves, as 99 percent of those animals will eventually be given up and usually euthanized. Basically, wolves are wild animals, more independent, hard to control, hard to manage, and health-keeping conditions are impossible to provide in the human home, thus tame wolves kept as pets are a real danger to their environment and to themselves.”