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Dog friendliness and the ‘happy gene’

two dogs smiling with their tongues out while they run through a field

Our dogs’ happiness is certainly contagious. No matter how long or short a time we’ve been away from home, they greet us like the best friends we are – tail wagging and full body wiggling. The offer of a game with a tennis ball, taking a leash or the car keys out, or the rustle of treats in a bag can set off a storm of excited wags and spins. It almost seems like our fur friends are hard-wired to be happy, and, in fact, scientists are finding that there is a genetic basis for dog friendliness and happiness.  

Table of Contents:

The research

In 2010, a team of researchers from Princeton, Oregon State University, and other institutions wanted to discover if there was a genetic reason for dog happiness and friendliness and to explore why some dogs are more human-seeking and friendly than others. They wanted to see if genetic variations supported the link between dog sociability and the early domestication of dogs. By testing dogs and wolves that had been raised by humans, the researchers noted that the dogs, regardless of breed, were friendlier and more human-centered than the wolves, even though the wolves had also been raised by humans. They continued the investigation to determine if certain behaviors are gene-based and to pinpoint where in the dogs’ genetic makeup this behavior might stem from.  

The human connection 

The research team focused on one area of dog DNA initially because some humans have a genetic variance that results in a rare genetic disorder called Williams-Beuren syndrome. These individuals have developmental and intellectual delays along with certain physical traits. They also display a remarkably friendly and outgoing personality with low social inhibition, sometimes known as ‘cocktail party personality’. Individuals with Williams-Beuren syndrome are known to have a gene deletion on chromosomes in what is called the Williams-Beuren Syndrome critical region, or WBSCR. Reasoning that extreme friendliness might be gene-linked for both humans and dogs, the researchers focused their attention on this chromosomal region.  

The scientists found the behavioral differences between the wolves and the dogs could be traced to differences in this one chromosomal area, the WBSCR. Dogs who had many additions, known as transposons or jumping genes, of the WBSCR of their DNA exhibited the most social behavior toward humans. The wolves did not show additions to these genes. They were interested in interacting with humans but quickly became more independent from them. In particular, the genes GTF21 and GTF21RD1 seemed to be responsible for this behavior trait. These are the same genes that are disrupted, although by deletion of DNA rather than additions, in individuals with Williams-Beuren. 

Are certain breeds friendlier? 

This research offers an explanation that the evolution of wild wolves to domesticated dogs tens of thousands of years ago might have been linked to their genetic predisposition to seek out the companionship of humans. It had long been thought that humans enticed wild wolves and domesticated them for protection and companionship, but it now seems that certain animals were genetically predisposed to seek attention from people and be extremely social. People started intentionally breeding dogs about 2,000 years ago, primarily for certain qualities to make them good companions or workers.  Only in last few hundred years have dogs been bred for the specific physical traits such as coat color or size that are breed markers.

Elinor Karlsson, the director of the Vertebrate Genomics Group at the Broad Institute (a Harvard/ M.I.T. collaboration that is a leader in the genomic research field), determined that while there is a genetic component to dog behavior, it is not linked to certain breeds. Golden Retrievers, for example, are not genetically more likely to be extremely friendly than other breeds or mixed-breed dogs just because of their breed. Golden Retrievers do show this genetic friendliness trait, but it has probably been passed along because hyper-sociability is so desired in dogs that dogs with it are more likely to be bred. Karlsson’s research found that the genetic differences between breeds were mostly in physical characteristics, not behavioral. 

What is the impact? 

The discovery of this ‘happy gene’ has led to speculation that genetic engineering could be used to create dogs with certain personality traits. Bridgett vonHoldt, the lead researcher in the Princeton study, said that this type of genetic engineering is a possibility but that its realization is still far off in the future. She did note, however, that their findings suggest that dogs and humans may share some of the same genetic pathways that control social behavior. The discovery of this shared genetic trait could have implications for further genetic research in humans. Dogs have been used recently in genetic studies that could have strong correlations with human behavior and could lead to new insights in finding the genetic basis for certain psycho-social behaviors. Genetic research continues on people’s degrees of happiness and why those from some countries are consistently measured as being happier than others. For the time being, though, we’ll just enjoy our joyful, happy pups.