Dogs and wolves are very different from each other in many ways. They’re very similar to each other in many others. Understanding the biological basis of these differences can help us understand our dogs better – why some dogs do better as pets and why others are more fearful, more aggressive, or less social. But where do we start?
In a 2010 study, Bridgett vonHoldt and a team of researchers started by comparing dog and wolf genetics (Pollinger et al., 2010). Dogs and wolves are extremely genetically similar; dogs are a subspecies of wolf, and can easily breed with wolves and produce fertile offspring. (In fact, this dog/wolf intermixing happens frequently enough that it confounds some genetic studies!) The vonHoldt team compared canine and lupine genomes to find areas that were distinctly different. This is a widely-used approach to find areas containing the genes that actually control the physiological differences we’re interested in – the genes that were theoretically changed (were “under selection”) when ancient canids diverged into dogs and wolves.
This 2010 study identified several interesting areas of the canine/lupine genome, but arguably the most intriguing of those was an area similar to a region that is missing in humans who have Williams-Beuren syndrome. This syndrome results in people who are extremely sociable and extremely trusting, and have some associated physical issues, like unusual facial structure, mild mental retardation, and heart defects. This led researchers to ask if some of the genes missing in Williams-Beuren syndrome were associated with increased trust and sociability, and whether these same genes differed between dogs and wolves. But which genes specifically? And how exactly do they affect behavior?
The followup study addressing these questions was just published last month (Schuldiner et al., 2017). In this 2017 study, von Holdt and her team looked at both genetics and behavior in dogs and wolves. With a small set of dogs (18) and wolves (10), they performed behavioral and genetic tests, and then did indeed find an association between genetics (in this area of the genome related to Williams-Beuren syndrome) and personality (specifically sociability). Moreover, they found that the versions of genes associated with increased sociability were more common in dogs, and the versions associated with decreased sociability were more common in wolves and coyotes.
Of course, the question of what the differences are between dogs and wolves is still wide open. This study took us a step forward, but there remains lots left to do. The gene variants pinpointed in this 2017 study remain mysterious. What do they actually do? Moreover, the sample size was very small – it’s hard to find a big population of socialized wolves to run these complicated behavioral tests on! Will the study even hold up in a larger sample size? What about other tests – what other aspects of personality might these genes affect? Finally, personality is controlled by many, many genes, of which these new candidates are just a few. We have many more genes left to find! However, this progress is important: von Holdt’s team identified a small number of genes that are worth examining much more closely, to help researchers continue to unravel the question of how genetics affects behavior and what makes dogs so sociable and trusting.
Pollinger, John P., et al. “Genome-wide SNP and haplotype analyses reveal a rich history underlying dog domestication.” Nature 464.7290 (2010): 898. – (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3494089/)
Shuldiner, Emily, et al. “Structural variants in genes associated with human Williams-Beuren syndrome underlie stereotypical hypersociability in domestic dogs.” Science Advances 3.7 (2017): e1700398. – (http://advances.sciencemag.org/content/3/7/e1700398.full)
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