Epigenetic variation predicts behavior in dogs

Dogs are very different from one another – they can be reserved or friendly, fearful or bold, calm or playful, or prone to bark or not. Although previous research has shown that many of these differences are genetically determined, even within dog breeds – where artificial selection has led to the loss of much of the original genetic variation – the behavior of individual dogs can vary substantially.

Now, a research team led by the University of California, Los Angeles (UCLA) has found that part of the differences in dogs’ temperament – especially their energy levels and fear-related behaviors – actually depend less on genetics than on acquired differences in their epigenome, which can depend on age, diet, exercise, training, socialization, and other environmental factors.

“Here we show that the behavior of dogs is associated with their epigenome, in particular DNA methylation. Our results open the door to using epigenetics to screen and select for desired behavioral traits in companion or service dogs,” said study senior author Matteo Pellegrini, an expert in Epigenomics and Computational Biology at UCLA.

The scientists quantified the genetic, epigenetic, and behavioral differences between 46 female and male dogs from 31 different breeds, with ages ranging from one to 16. While dog owners had to complete a survey to help researchers identify dogs’ behavioral traits, the pets’ epigenome was reconstructed from epithelial and immune cells obtained from swabs inside the dogs’ cheeks.

The analysis revealed that the epigenome was a better predictor of behavior than the genotype. For instance, differences in DNA methylation between dogs explained a far greater proportion of variation in energy, attention seeking, nonsocial fear, or stranger-directed fear than genetic differences did.

“These associations between the DNA methylation of cells in the mouth and dog behaviors were surprising, and suggest that future studies that examine DNA methylation in nerve tissues may identify similar patterns,” said Pellegrini. “We plan to conduct much larger studies in the future, with the goal of developing biomarkers that allow us to better identify dogs with specific behavioral predispositions.”

“Ultimately, we would be very interested in examining the epigenomes of highly specialized dogs such as guide dogs or sled dogs, to be able to assist in the selection of dogs that might be more likely to successfully complete their training,” he concluded.

The study is published in the journal Frontiers in Psychology.

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By Andrei Ionescu, Earth.com Staff Writer

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