Wolves may share the ability of their close cousins, dogs, in attaching to human caregivers.
Dogs are man's best friend, and a large part of their friendship is the level of attachment dogs can show to those who care for and live alongside them. According to new research, wolves also share this ability to show attachment behavior towards their human caregivers.
The most important implications of these findings are that they underscore how wolves -- the wild ancestors of dogs -- can readily form strong bonds to humans.
Friends of wolves
The paper adds to a body of accumulating evidence that contradicts the hypothesis that dogs' ability to bond with humans was something bred into them during the domestication process.
"We felt that there was a need to thoroughly test this," says Dr. Christina Hansen Wheat, PhD in Ethology from Stockholm University, Sweden and lead author of the paper. "Together with earlier studies making important contributions to this question, I think it is now appropriate to entertain the idea that if variation in human-directed attachment behaviour exists in wolves, this behaviour could have been a potential target for early selective pressures exerted during dog domestication."
The findings are based on a study with 10 European grey wolves and 12 Alaskan husky dogs, which aimed to quantify and compare the level of attachment behaviours in these species. The wolves in this study were around 5 months (23 weeks) old at the time of the experiment.
Each of the animals was put through a discrimination task. This consisted of alternating between the presence and absence of a stranger and/or a familiar person in the test room with the animal. The familiar person was the primary caregiver for all of the pups, a woman that had raised and spent the most time with the animals since they were 10 days of age. The stranger was another woman, but who had never met neither the wolves nor the huskies.
The experimental room measured 6 by 6 meters (19.5 sq ft) with two chairs placed 2m away from each other in the middle of the room facing the same direction. Seven toys such as balls, rope, and rubber animals were brought into and distributed across the room from the home enclosures of the animals -- familiar toys were used in order to avoid influencing the experiment's outcome. Two diagonally-mounted GoPro cameras were used to record each animal's reaction during the experiment.
"A total of seven behaviors were quantified [...]. These seven behaviors included: (1) greeting, following, physical contact, and standing by the door -- all categorized as safe haven effects, which are expressed as a means to maintain proximity or physical contact with the attachment figure; (2) exploration and play -- both categorized as secure base effects, which can be expressed more in the presence of the attachment figure; and (3) passive behavior -- categorized as other behavior related to other aspects of the social and physical environment," the study explains.
Boiled down, what the experiment set out to determine was if wolves and dogs could discriminate between strangers and familiar people when in a strange situation. They did this by checking if the animals would spend more time greeting and in physical contact with the familiar person and show them more affection than they would a stranger.
All in all, the wolves spontaneously discriminated between the familiar and unfamiliar person similar to the dogs, showing more proximity-seeking and affiliative behaviors toward the familiar individual. Furthermore, both groups benefited from the presence of the familiar person, who acted as a buffer against social stress -- in other words, both the wolves and the dogs were calmed by the presence of the familiar person during stressful situations. This suggests that the ability to bond with humans is equally-shared among dogs and wolves, and wasn't something bred specifically into dogs through domestication.
"It was very clear that the wolves, as the dogs, preferred the familiar person over the stranger. But what was perhaps even more interesting was that while the dogs were not particularly affected by the test situation, the wolves were," says Dr. Hansen Wheat. "They were pacing the test room."
"However, the remarkable thing was that when the familiar person, a hand-raiser that had been with the wolves all their lives, re-entered the test room the pacing behaviour stopped, indicating that the familiar person acted as a social stress buffer for the wolves. I do not believe that this has ever been shown to be the case for wolves before and this also complements the existence of a strong bond between the animals and the familiar person."
Although this similarity between dogs and wolves can seem surprising, Dr. Wheat explains that it does make more sense looking back. Being able to attach to humans would make for a distinctive advantage in the early stages of domestication for any animal.
In other words, it's not that dogs grew closer to humans as they were domesticated, but their ability to become close to us is why they were so readily domesticated in the first place.
The paper "Human-directed attachment behavior in wolves suggests standing ancestral variation for human–dog attachment bonds" has been published in the journal Ecology and Evolution.
