If you think dogs are drawn to your winning personality then think again -- the attraction may be genetic, according to a study released Thursday that pinpoints genes linked to inter-species amity.
Providing food and playing fetch, of course, also forge strong bonds.
But experiments involving several hundred dogs, and a sweeping analysis of their genomes, uncovered a handful of genetic variants clearly linked to canines being friendly with humans.
The same genes, it turns out, help govern sociability in our species, and are implicated in neurological problems ranging from autism to ADHD.
"Our findings suggest that there may be a common underlying genetic basis for social behaviour in dogs and humans," senior author Pers Jensen, a professor of ethology at Linkoping University in Sweden, told AFP.
The first domesticated dogs -- some 15,000 years ago -- were probably wolves that had grown accustomed to the presence of humans in their habitat, most experts agree.
Since then, man's best friend has continued to evolve, a process likely influenced by our intimate co-habitation.
Indeed, one of the ways in which dogs diverged from wolves was by developing an innate tendency to seek our companionship, earlier research has shown.
Several experiments, for example, compared the behaviour of puppies and wolf pups raised as family pets. The baby wolves were taken from their mothers at about eight weeks old.
When confronted as adults -- in the presence of humans -- with so-called "impossible tasks" that they could not resolve, the dogs and socialised wolves behaved quite differently.
"In general, dogs had a strong tendency to solicit human help, whereas wolves" -- even those raised as pets "did not," said Jensen.
Jensen and colleagues performed a similar test with more than 400 beagles born and raised in a kennel that produced animals for laboratory tests.
Importantly, all the animals came to maturity under the same conditions and with the same level of human contact.
In the experiments, each beagle tried to lift clear plastic lids off three bowls in order to get an edible treat below.
- Looking At Wolf Genomes -
The first two tests were easy, but the third lid was impossible to move.
The researchers recorded the dogs' reactions, especially to what extent they turned to a person in the room, as if to seek assistance.
The next step was to examine the DNA coding of each dog's genome to look for matches between its behaviour in the experiment and specific genetic variants, or mutations.
Jensen and his team found five genes that correlated strongly with the dogs most inclined to seek human help -- the same genes related to sociability in humans.
The two that stood out the most are known as SEZ6L and ARVCF.
It is still unclear exactly how these genes exert on influence, or whether they are simply markers of some other process as yet undetected. That's a very difficult question to unravel.
There is another puzzler, however, that can be resolved: did these genetic variants evolve during the domestication of dogs, or have they been there all along?
To find out, Jensen is now sequencing the genes of wolves to see if they have the same variants.
If they don't, it would strongly suggest that these "sociability genes" arose recently.
But it is also possible, he said, that the first wolves to join the community of humans had precisely the same mutations that may have made some of the dogs in the experiment more likely to nuzzle up to a two-footed friend.
"My gut feeling is that there is the same kind of gene variations in the wolf population," Jensen said.
The kennel, by the way, went out of business, which means that all the beagles found homes, he added.