MIAMI, Florida - Dogs that are extra friendly share certain genetic similarities with people who are born with a developmental disorder sometimes called the "opposite of autism," which makes them hyper social, researchers said Wednesday.

The report in the journal Science Advances pinpointed changes in two genes that are related to extreme social behavior in dogs, and also in people who are born with Williams-Beuren Syndrome.

People with this condition tend to be highly outgoing, gregarious, empathetic, interested in prolonged eye contact, prone to anxiety and may have mild to moderate learning disabilities and intellectual impairment.

The findings offer new insights into how dogs became domesticated and split paths from their wolf ancestors thousands of years ago.

"It was once thought that during domestication dogs had evolved an advanced form of social cognition that wolves lacked," said co-author Monique Udell, an animal scientist at Oregon State University.

"This new evidence would suggest that dogs instead have a genetic condition that can lead to an exaggerated motivation to seek social contact compared to wolves."

Researchers studied 18 domesticated dogs and 10 captive gray wolves to see how social they were toward people and how they performed on problem-solving tasks.

Given the task of lifting a puzzle box lid to get a sausage treat, the canines were rated on how much they turned to a human in the room for help.

The wolves were more likely to figure out how to get the treat than dogs. The dogs were more likely to stare longingly at the nearby people.

Then, researchers took blood samples and to see how the wolves' and dogs' genetic traits lined up with their personalities.

They found variations in two genes - GTF2I and GTF2IRD1 - "appeared to be connected to dog hyper sociability, a core element of domestication that distinguishes them from wolves," said the report.

These genes have previously been implicated in the hyper social behaviors of humans with William-Beuren Syndrome.

Adam Boyko, an assistant professor at Cornell University and expert in dog genetics, called the study "truly interesting and important".

"It may be one of the first studies to ever identify the specific genetic variants that were important for turning wolves into dogs," he said in an email.

Agence France-presse