Why are dogs so friendly to their human companions? As it turns out the, answer may be in their genes, according to new research published by scientists at Oregon State University.

Dogs are descended from wolves tens of thousands of years ago, and over that time their genes have adapted to make them friendly toward humans and desiring their company. Scientists based this conclusion on studying the behavior of domestic dogs and comparing them with grey wolves that live in captivity. They also gave the animals tests for problem-solving and sociability.

Researchers found that wolves were just as good at solving problems as dogs, but dogs were much more friendly, spending more time greeting human strangers and staring at them, whereas the wolves preferred to ignore the humans. Scientists think that this can be explained by genes.

“The genetic basis for the behavioral divergence between dogs and wolves has been poorly understood, especially with regard to dogs’ success in human environments,” Monique Udell, an animal scientist at Oregon State University and lead co-author of the study, said in a statement. “It was once thought that during domestication dogs had evolved an advanced form of social cognition that wolves lacked. 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.”