Why dogs are our best friends: it’s in their genes

What is most important: looks, brains or personality? All have played a part in endearing dogs to humans, but a new study lends weight to the view that a hardwired personality trait – sociability, to be specific – has been the crucial factor in the domestication of man’s best friend.

The study pinpoints the increased social tendencies shown by dogs compared with their closest wild relatives, wolves, to variations in two genes, known as GTF2I and GTF2IRD1. Intriguingly, the deletion of these genes in humans has been linked to Williams-Beuren syndrome (WBS), a congenital disease that leads to hyper-social behaviour.

It has been previously theorised that the behavioural divergences between dogs and wolves are due to dogs having evolved higher social cognition, but the researchers behind this new study point to mounting evidence of human-socialised wolves demonstrating equal or greater socio-cognitive performance to domestic dogs, while dogs have a clear edge in exaggerated gregariousness, referred to as hypersociability.

To reach their conclusions, the team of researchers led by Bridgett vonHoldt, of Princeton University, investigated the sociability of a group of domestic dogs and human-socialised grey wolves using a combination of DNA analysis and behavioural data.

Their paper notes that little is still known about the genetics underpinning the behavioural traits associated with canine domestication compared to, say, the genetics responsible for differences in physical traits like fur colour and size.

For the behavioural component of this research, which is outlined in Science Advances, the wolves and dogs were put through a series of sociability and problem-solving exercises. These included a trial in which the canines were required to open a puzzle box that contained a treat, both alone and in the presence of a human stranger.

The dogs showed more attention to social stimuli (the human strangers) and spent a greater proportion of their time in the experiment gazing at the person, when present.

The DNA analysis focused on a specific chromosomal region that is positively selected for in domestic species of dog – ergo, it is passed on through the population as an evolutionary advantageous trait.

The results and conclusions are noteworthy because they support an alternative theory for the behavioural divergence between dogs and wolves, in which the spread of genes through breeding was the primary factor that allowed the former species to coexist successfully with humans.

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