For centuries, humans have speculated whether dogs truly feel complex emotions such as jealousy. Philosopher Peter Singer, in his 2018 commentary published in Animal Sentience, revisited this question through the lens of neuroscience, responding to findings by Cook et al. (2018) that provided the first direct brain-based evidence of jealousy-like responses in dogs.
Using non-invasive fMRI techniques, Cook and colleagues observed that when dogs saw their caregivers feeding another dog, there was heightened activation in the amygdala—a brain region linked to emotional arousal, including fear, anger, and jealousy in humans. This physiological response did not appear when dogs saw their caregiver interact with a neutral object. Dogs known to have more aggressive temperaments showed stronger amygdala responses, suggesting individual emotional variation similar to that seen in people.
While previous behavioral studies, such as those by Harris and Prouvost (2014), had already demonstrated jealousy-like actions—such as snapping, pushing, or attention-seeking—Singer noted that these new neural data added powerful support for the idea that dogs experience a “primordial form of jealousy.” This form does not require complex social reasoning but reflects a basic emotional reaction to perceived threats to an important relationship.
Singer emphasized two major ethical implications. First, the study demonstrated how compassionate scientific methods—reward-based training and voluntary participation—can be employed without causing distress. Second, the findings challenge long-held assumptions about human emotional uniqueness, reinforcing Darwin’s claim that the mental difference between humans and animals is one of degree, not of kind.
For Singer, these insights expand moral consideration toward dogs and other social mammals, whose emotional lives may be richer and more human-like than many assume. Recognizing jealousy and similar emotions in dogs not only advances animal cognition research but also calls for greater empathy and ethical responsibility in how humans treat their canine companions.
Source: Singer, P. (2018). Finding the green-eyed monster in the brain of a dog. Animal Sentience, 3(3). Commentary on Cook et al. (2018). Published 2018.
