Read More: New Scientist
The ancestral wolves that evolved into domestic dogs may have carried genetic mutations that made them socialise more readily with people. What’s more, the same genes cause excessive sociability in humans. It was already known that even if wolves have been raised with humans from birth, they never become as close to people or look at them as often as dogs tend to. Several years ago, Bridgett vonHoldt at Princeton University in New Jersey and her colleagues linked this “hypersociability” to a 28-gene stretch of the dog genome that includes canine versions of the genes responsible for Williams syndrome – a human disorder characterised by extreme sociability. However, they had no direct proof that these genes caused it. To find out whether they do, vonHoldt and her team tested the behaviour of 18 domestic dogs and 10 wolves, all of which had been raised identically with constant human contact. Each animal was scored for its hypersociability towards humans. As expected, the dogs scored higher than the wolves. The researchers then sequenced the key region of each animal’s genome in fine detail and searched for structural variations – deletions or insertions of genetic material – that seemed to match well with their social behaviour. They found four, including two in genes called GTF2I and GTF2IRD1. These genes are known to cause the hypersociability involved in Williams syndrome in humans, and GTF2I has also been shown to cause hypersociability in mice.