Wolves Can Show Attachment Toward Humans

Summary: Wolves, like dogs, prefer the presence of a familiar person over that of a stranger. Familiarity with a human has a positive and calming impact on a wolf’s social behavior.

Source: Stockholm University

When it comes to showing affection towards people, many dogs are naturals. Now comes word reported in the journal Ecology and Evolution on September 20th that the remarkable ability to show attachment behaviour toward human caregivers also exists in wolves.

The findings were made when researchers at Stockholm University, Sweden, tested 10 wolves and 12 dogs in a behavioural test specifically designed to quantify attachment behaviours in canids. During this test 23-week-old wolves spontaneously discriminated between a familiar person and a stranger just as well as dogs did, and showed more proximity seeking and affiliative behaviours towards the familiar person.

Additionally, the presence of the familiar person acted as a social stress buffer for the wolves calming them in a stressful situation.

These discoveries build on a slowly accumulating body of evidence contradicting the hypothesis that the abilities necessary to form attachment with humans, arose in dogs only after humans domesticated them at least 15,000 years ago.

“We felt that there was a need to thoroughly test this,” says Dr. Christina Hansen Wheat, PhD in Ethology from Stockholm University, Sweden. “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.”

Dr. Hansen Wheat is interested in understanding how domestication affects behaviour. To study this, she and her team raised wolf and dog puppies from the age of 10 days and put them through various behavioural tests. In one of those tests, a familiar person and a stranger takes turn in coming in and out of a test room to create a somewhat strange and stressful situation for the animal.

The theory behind the test, originally developed to assess attachment in human infants, is that by creating this unstable environment attachment behaviours, such as proximity seeking, will be stimulated.

In essence, what the researchers were looking for in this Strange Situation Test was if the wolves and dogs could discriminate between the familiar person and the stranger. That is, did they show more affection, and spend more time greeting and in physical contact with the familiar person than the stranger. If wolves and dogs would do so equally it would point towards this ability not being unique to dogs, i.e. it has not evolved specifically in dogs.

This shows a wolf pup
The wolf pup Hendris. Credit: Christina Hansen Wheat/Stockholm University

“That was exactly what we saw,” says Dr. Hansen Wheat.

“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. 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.”

Dr. Hansen Wheat adds that similarities between dogs and wolves can tell us something about where the behaviour we see in our dogs come from. And, while it may be a surprise to some that wolves can connect with a person in this way, she says in retrospect it also makes sense.

“Wolves showing human-directed attachment could have had a selective advantage in early stages of dog domestication,” she says.

Dr. Hansen Wheat will now continue to work with the data she and her team have collected over the course of three years hand-raising wolves and dogs under identical conditions to learn even more about their behavioural differences and similarities.

The article “Human-directed attachment behaviour in wolves suggests standing ancestral variation for human-dog attachment bonds” is published in Ecology and Evolution.

This research did not receive any specific grants from funding agencies in the public, commercial, or not-for-profit sectors.

About this animal behavior research news

Author: Karin Tjulin
Source: Stockholm University
Contact: Karin Tjulin – Stockholm University
Image: The image is credited to Christina Hansen Wheat/Stockholm University

Original Research: Open access.
Human-directed attachment behaviour in wolves suggests standing ancestral variation for human-dog attachment bonds” by Christina Hansen Wheat et al. Ecology and Evolution


Human-directed attachment behaviour in wolves suggests standing ancestral variation for human-dog attachment bonds

Domesticated animals are generally assumed to display increased sociability toward humans compared to their wild ancestors. Dogs (Canis familiaris) have a remarkable ability to form social relationships with humans, including lasting attachment, a bond based on emotional dependency.

Since it has been specifically suggested that the ability to form attachment with humans evolved post-domestication in dogs, attempts to quantify attachment behavior in wolves (Canis lupus) have subsequently been performed.

However, while these rare wolf studies do highlight the potential for wolves to express human-directed attachment, the varied methods used and the contrasting results emphasize the need for further, standardized testing of wolves.

Here, we used the standardized Strange Situation Test to investigate attachment behavior expressed in wolves and dogs hand-raised and socialized under standardized and identical conditions up until the age of testing.

We found that 23-week-old wolves and dogs equally discriminated between a stranger and a familiar person, and expressed similar attachment behaviors toward a familiar person. Additionally, wolves, but not dogs, expressed significantly elevated stress-related behavior during the test, but this stress response was buffered by the presence of a familiar person.

Together, our results suggest that wolves can show attachment behaviors toward humans comparable to those of dogs.

Importantly, our findings demonstrate that the ability to form attachment with humans exists in relatives of the wild ancestor of dogs, thereby refuting claims that this phenotype evolved after dog domestication was initiated.

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