Genes revealed to make dogs dumbbut loveable
In all the animal kingdom there is no love quite like the slobbery and adoring affection of a dog for its owners.
Scientists have found strong biological links between this boundless geniality and a "hypersociability" syndrome in humans, suggesting that dogs may have evolved to become friendlier and more child-like to secure their survival.
When they are very young, both dogs and wolves will treat the people who look after them like their parents. While wolves swiftly grow out of this habit, dogs tend to retain it, staying in a state of more or less babyish dependency for the rest of their lives.
A group led by Bridgett von Holdt, an evolutionary biologist at Princeton University in the US, has discovered that the genes driving this behaviour are very much like the mutations that lead to Williams syndrome, a rare human learning disability that makes people highly credulous and outgoing. The researchers suspect this was no accident: the genetic change appears to help dogs extend their mental childhood indefinitely, preserving their appeal as pets but sacrificing some of their intelligence.
They set up an experiment to test the "exaggerated gregariousness" of 18 dogs, including a Jack Russell, a border collie and a golden retriever, and 10 tame wolves that had been hand-reared from birth. In the first task the animals had two minutes to open a box containing a piece of sausage while a stranger stood near by. The wolves excelled at the job. Eight solved the puzzle inside the time and not one of them cast a single glance at the human. The dogs spent only 6 per cent of their time on the puzzle and 21 per cent gazing at the stranger instead. Only two of them extracted the sausage.
The scientists then analysed the animals’ DNA and zeroed in on two particular genes, GTF2I and GTF2IRD1, which are master switches that control the activity of many other sections of DNA. Humans usually have two copies of each; the absence of one copy leads to Williams syndrome.
Dr von Holdt said that some of the effects of these gene deletions seemed to be similar in dogs and humans: obsessive amiability, a tendency to be easily distracted by other people and a lack of wariness towards strangers.
The paper is published in the journal Science Advances.