Researchers in Japan have found in their study that two gene mutations in dogs are responsible for making them human beings' best companions.
First domesticated 29,000 years ago, dogs are considered man's best friend today all over the world.
According to the paper published in the journal Nature, some genetic mutations make dogs more comfortable interacting with humans.
Prior to this particular study, other researchers had suggested that genes had a role in the domestication of dogs. This Japanese study, however, pointed out what the mutations are.
"During domestication, dogs experienced strong selection for temperament, behaviour, and cognitive ability," the team said in the study.
About 624 domestic dogs were made a part of the study and divided into two groups. One group had pups closely related to wolves such as Husky and Akita in the "Ancient group". The "general group" comprised all other breeds.
The dogs were given two tasks. In the first, dogs were to guess under which bowl there was food by peoples' cues like gazing or pointing.
This assignment was to test how well dogs could understand humans' gestures.
No difference was observed between the two breeds. In the second task, the dogs were given a problem-solving test, where they had to try to open a container to get food.
Experts observed the amount of time the dogs looked at the experimenters for help.
The Ancient group looked at the experimenters less than the general group, suggesting their detachment from humans and less dependence.
Following this behavioural difference, researchers studied the differences in genes and cognitive abilities.
The results showed that there were two mutations in MC2R, the melanocortin 2 receptor, responsible for the production of cortisol (stress hromone) and genes for Oxytocin (often called the love hormone).