Dogs have two gene mutations that explain why they are friendly

A genetic and behavioural study has identified two mutations in a gene called melanocortin 2 that help explain why dogs are so social to humans

By Jason Arunn Murugesu

Dogs may have developed the social skills to interact with humans in part due to mutations in a stress-response gene.

Miho Nagasawa at Azabu University in Japan and his colleagues analysed genetic variations in four genes in 642 domesticated dogs.

The team chose the four genes – oxytocin (OT), oxytocin receptor (OTR), melanocortin 2 receptor (MC2R) and a gene called WBSCR17 – because they are all involved in how dogs respond to stress.

“Dogs’ social cognitive abilities are thought to have been acquired as a by-product of mutations of the stress response,” says Nagasawa.

After looking at the dogs’ genes, the team gave the animals two tasks to test their interactions with humans.

In the first, the animals were trained to find food hidden under one of two bowls. Each dog was then tasked with determining which bowl had food hidden underneath by looking at an experimenter’s cues.

In the second task, the dogs were trained to open a bin in order to find food inside. Each dog was then presented with the same bin, but this time it couldn’t be forced open. The dog’s behaviour was recorded for 2 minutes, while the team measured the frequency and length of time the animal spent looking at the experimenters.

In the first task, the researchers found that dogs with a specific mutation in the melanocortin-2 receptor gene could more effectively use the experimenter’s cues to choose the correct bowl. In the second task, the researchers found that dogs with another mutation in the melanocortin 2 receptor gene gazed at the experimenter for longer than dogs without this gene variant.

Nagasawa says mutations in the melanocortin 2 receptor gene may have reduced fear and aggression in dogs, leading them to be braver in their approaches with humans.

“We believe that understanding animals that can coexist with humans will provide hints for humans to coexist with… animals of other species,” says Nagasawa.

“Dogs are excellent models to study the genetic basis of complex behaviours and [for] identifying genetic variations that explain the unique human-animal bond,” says Juliane Friedrich at the University of Edinburgh, UK. “The variants identified in this study are further important puzzle pieces to help us to better understand the biological mechanisms underlying this close interspecies bond.”

Journal reference: Scientific Reports, DOI: 10.1038/s41598-022-11130-x

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