LOS ANGELES, July 21 (Xinhua) -- Three genes on chromosome 6 are closely correlated with dogs' friendliness, which are distinct from wolves, according to a new study, published in the journal Science Advances this week.
These three genes can also make some people hyper-social, the Los Angeles Times reported on Friday.
Researchers from Princeton University and Oregon State University selected 18 dogs and ten gray wolves, who had the experience of socializing with humans, to do a series of behavioral tests.
When given a puzzle box and sausage hidden inside, only two dogs opened the box regardless of whether a human was on the scene or not. Meanwhile, eight of the ten wolves opened the box when a human was present, and nine of them opened the box when the human had left.
The researchers concluded that dogs are not as independent as wolves are, and are more easily distracted by social stimulation, which also confirmed the conclusions of previous studies.
During the sociability test, the researchers arranged strangers and owners to spend two minutes with the dogs and wolves respectively, to find out how much time the canines would spend with humans.
In the first round, both the strangers and owners stayed passively without talking or eye contact with the canines, and in the second round, they interacted with the canines.
The result showed that when their owners or caretakers showed up, dogs spent a median of 93 percent of their time with humans, while wolves spent only 36 percent of their time with them. However, when strangers appeared, dogs cuddled with humans for 53 percent of the time, yet wolves did so only 28 percent.
In order to find the connection between the sociability of each canine and the structure of their DNA, the researchers took blood samples from 16 dogs and eight of the wolves to further analyze their DNA on chromosome 6.
Researchers found that the canines who were more social had much more mutations in those three genes. The two wolves which socialized more with humans also had more mutations in these three genes, which are named GTF2I, GTF2IRD1, and WBSCR17.
It is interesting that the mutations in the same three genes can cause a rare developmental disorder in humans, called Williams-Beuren Syndrome, or WBS.
"People with WBS are typically hyper-social, meaning they form bonds quickly and show great interest in other people, including strangers," the Los Angles Times said.
Some scholars pointed out the sample of the study was small and a larger sample size might be more convincing.
The authors of the study acknowledged that their sample size was not large enough, but they would do a larger sample in the future, and they believed that the correlation between DNA and social behaviors is obvious.
They would continue to explore related questions in more detail, such as how genetic mutations result in increased social behavior.
