Fear, anxiety, and aggression are important emotional traits that affect dogs’ health, welfare, and social interactions. Zapata et al. (2016) conducted genome-wide association (GWA) mapping across hundreds of dog breeds to identify genetic loci linked to these behaviors. Their findings reveal a strong genetic component behind canine emotional reactivity.
The researchers found that IGF1 and HMGA2 loci, already known for influencing small body size, were also associated with separation anxiety, touch sensitivity, owner-directed aggression, and rivalry with other dogs. Beyond size-related genes, the study uncovered two additional regions of interest: the GNAT3-CD36 locus on chromosome 18 and the IGSF1 locus on the X chromosome. These loci were linked to touch sensitivity, non-social fear, and aggression toward unfamiliar humans and dogs.
Crucially, all four identified loci are among the most evolutionarily selected regions in the dog genome, pointing to their importance in shaping behavior during domestication. The authors suggest that reduced-fear variants at these loci may have played a key role in the transition from wolves to companion dogs, allowing for greater sociability with humans.
The study highlights how behavior and morphology share overlapping genetic influences, but also demonstrates distinct variants tied solely to behavior. For example, while CD36 is widely expressed in the body, it is particularly enriched in the amygdala and hypothalamus, brain regions central to fear and aggression. This strengthens the case for genetic contributions to emotional differences across breeds.
Source: Zapata, I., Serpell, J., & Alvarez, C. E. (2016). Genetic mapping of canine fear and aggression. BMC Genomics, 17. Published August 8, 2016.
