Border collies like Fly from the movie "Babe" and Labrador retrievers such as "Old Yeller" were originally selected to perform tasks for us, but different ones: herding livestock and gundog work, respectively. According to new findings published in Scientific Reports this week, border collies are more impulsive than Labrador retrievers on average. The nature of their work required different levels of impulse control.
Studies with dogs can help us understand human personalities and disorders since their repertoire of behaviors are simpler, yet similar enough for comparable conclusions. In dogs, impulsivity – the inability to inhibit certain behaviors and delay reward gratification – is related to aggressive behavior. Higher levels of impulsivity are linked to low levels and poor regulation of serotonin and dopamine. And in humans, this is related to behavioral disorders and even violence.
To study the effects of different selective pressures on impulsivity, a University of Lincoln team led by Fernanda Ruiz Fadel collected data on 716 border collies and 445 Labrador retrievers. The age, sex, and neuter or spay status of the 1,161 purebreds were recorded, and the owners answered a questionnaire with 18 behavioral items that they strongly agreed with or strongly disagreed with (and everything in between). Some examples from this Dog Impulsivity Assessment Scale include: "My dog doesn’t like to be approached or hugged," "My dog is not keen to go into new situations," and "My dog calms down very quickly after being excited." This allowed the team to measure factors like aggression threshold, behavioral regulation, and response to novelty.
Labrador retriever performing the role its breed was selected for. Shona Jenkins
The team found that border collies, on average, were more impulsive than Labradors – consistent with the original purpose of breed selection. However, the team only found a difference in levels of impulsivity when they compared the so-called working lines of the two breeds: There were no major difference between show lines of those breeds. When appearance, rather than behavior, becomes the primary focus for breeders, this reduces the differences in impulsivity between breeds.
In fact, the differences within breeds can exceed the differences between breeds. These findings caution against breed stereotyping: Predictions about an individual dog’s tendencies can’t be made based only its breed.
Since the study didn't measure levels of neurotransmitters, "we cannot say for sure that working line border collies have lower levels of serotonin, but we can speculate that this is the case," Fadel tells IFLScience. "Our paper shows that impulsivity can be selected for and vary widely between individuals, and this can be extrapolated to humans, as our neurotransmitters work the same way."