Understanding the genes behind dog sociability

A total of five genes relating to sociability were found in beagles.

Today’s Scientific Reports study has discovered genes that may be associated with human-directed social behaviors like attention seeking and remaining in close proximity to people. Per Jensen and his team from Linköping University, Sweden, studied the beagle’s tendency to engage with a human, including seeking eye contact, while attempting to solve an impossible task. The samples from the 190 beagles were then analyzed to identify the five candidate genes within two genomic regions that could be associated with sociability.

Per Jensen told us more about the study.

ResearchGate: What motivated this study? Why beagles?

Per Jensen: We are interested in domestication in general, and dog domestication in particular. One of the most astonishing differences between ancestral wolves and dogs is the ability of dogs to communicate and interact with humans. So we decided to attempt to find some of the genes which may have caused this difference. We chose beagles because we had access to a large population (about 500 dogs) bred at a kennel where their previous experiences with humans were highly standardized. There were therefore minimal effects of previous differences in training.

RG: Can you briefly explain how the study was carried out?

Jensen: Each dog was tested on their own with a human they met for the first time. They were presented with a simple problem; they were required to push three transparent lids to the side in order to obtain a treat under each. The last lid was tightened so it could not be moved, so the dog was presented with what turned out to be an impossible problem. A typical dog reaction in a situation like this is to turn to a human to “ask for help”, something wolves never do. We video recorded their behavior and scored time and frequency of human contact seeking behavior. We then took a DNA-sample with a buccal swab, and analyzed this DNA for genetic markers throughout their genomes. Finally, we used statistical methods to analyses whether dogs showing more social behavior towards humans would have any particular genetic variants in common, and we found a strong association with a chromosome region containing five genes.

Beagle attempting to solve an unsolvable task Credit: Mia Persson
Beagle attempting to solve an unsolvable task
Credit: Mia Persson

RG: How did you come up with the tasks for the dogs?

Jensen: The “unsolvable problem” has been used by others to analyze dogs’ propensity to seek human contact. We developed this specific variant in order to have a test that can be used in large screenings, without requiring any previous training. So the task first appears relatively simple, most dogs readily find out on their own how to flip the lid to the side. When they have succeeded twice, they are confident in their ability and go for the third lid as well, but this can of course not be opened. We tested on many dogs before using it in the present experiment, and it turned out to have the perfect balance between being understandable to a dog and yet in the end causing them sufficient problems to make them seek human help.

RG: What were your results?

Jensen: The dogs varied substantially in the propensity to seek contact with a human. Some gave up immediately and interacted intensely with the human, others were more “wolf-like” in their behavior, and continued to try and solve the problem on their own. The propensity to seek human contact was strongly associated with two specific chromosomal regions, which contained five different genes. Four of the genes have previously been identified as being associated with human social disorders, such as autism and ADHD.

RG: Where do you think these genes came from? Has the selective breeding of dogs by humans influenced this?

Jensen: The genes are present in all vertebrates, but what we have discovered is that some variants of the genes, or in how the genes are controlled, is related to sociality in dogs. We think that these variants have been selected during domestication. Humans have bred dogs that are more social for thousands of years, and therefore increased the prevalence of these gene variants in the dog population.

One of the research subjects together with the unsolvable task and one of the authors. Credit: Mia Persson
One of the research subjects together with the unsolvable task and one of the authors. Credit: Mia Persson

RG: How would the dogs benefit from having these genes?

Jensen: A dog with a genetic setup predisposing it for being more social towards humans would have an enormous selective advantage, since this is one of the most preferred traits in any dog compared to the wild ancestor. Today there is still obviously some variation within dog populations, and those dogs which have the social genetic setup will probably more often be selected for breeding by humans who prefer sociable and interactive dogs. But some dog breeds (not least beagles) are actually bred for independence and for hunting on their own and, in that case, humans probably select for the less sociable genetic setup.

RG: Do you think these genes could exist or even develop in other domesticated animals or breeds of dogs?

Jensen: This remains to be investigated, but I would be very surprised if we did not find the same variations in other breeds of dogs. With respect to other domesticated species, this remains more speculative, but it would be very interesting to look at, for example, horses, which are also bred for intense human cooperation.

RG: What are the next steps in your research?

Jensen: We need to test the same genes and the same behavior in other breeds, and this is already underway. Furthermore, we have obtained samples of wolf DNA, and we plan on examining whether they also have the same genetic variants. This can help us understand more about how this behavior could have evolved during domestication – did people select wolves which carried these genetic variants, or did they emerge later, perhaps as mutations somewhere along the domestication process?

Featured image courtesy of flickr.