Wolves that are raised by people may have similar levels of attachment to humans as dogs.
 and her colleagues assessed attachment behaviour in 12 Alaskan huskies from two different litters and 10 European grey wolves from three litters while Wheat was working at Stockholm University in Sweden.
For the first two months of their lives, each litter – whether dog or wolf – was separately hand-raised and extensively exposed to humans, with the 24-hour presence of human caregivers.
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Caregiver presence was gradually reduced to the point where the puppies spent every other night without a caregiver present after the age of four months.
The team found that both dogs and wolves showed similar attachment behaviours towards familiar people, such as greeting, following them around and expressing physical contact.
Both sets of animals were also able to discriminate between a stranger and a familiar person at 23 weeks old.
Similar tests have most commonly been used to explore and understand the relationship and behaviours that human children express towards their parents.
“The kind of emotional and cognitive background that allows these behaviours to be shown is common among mammals. The fact that we see it in wolves is actually not surprising because it’s something that they can show towards their mothers,” says at the University of Veterinary Medicine Vienna in Austria, who wasn’t involved in the study. “[But] the fact that they can show it towards humans raises questions.”
Domesticated animals have been thought to display more social attachment to humans than their wild ancestors. One suggestion has been that dogs evolved the ability to form attachments to people during the process of domestication.
“It wasn’t exactly clear whether we specifically selected for it or if it was something that dogs kind of acquired, but there was no consensus regarding this,” says Cimarelli.
The team at Stockholm University has shown that this sort of attachment isn’t limited to domesticated animals like dogs.
There were, however, some differences in the behaviour of the dogs and wolves. The wolf pups exhibited more signs of stress during the experiment, including pacing, crouching and tucking their tail between their legs – but this response was modulated by the presence of a familiar person.
The experiment also leaves some remaining questions, says Cimarelli. In particular, it is unclear what makes it so easy for dogs to accept humans as social partners even without the sort of intense socialisation that the wolf and dog pups experienced during this study.
Reference: BioRxiv,
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