Dogs Use Similar Brain Region As Humans To Process Numbers Of Objects

Basic sensitivity to numerical information is called numerosity, and it appears to be present throughout the animal kingdom without the need to rely on symbolic thought or training. The approximate number system supports the ability to quickly estimate the number of objects in a particular scene, whether it is the number of predators or, perhaps, the quantity of available food.

In humans, the ability is present even in infancy, and we rely on the parietal cortex for it. However, previous studies on the ability involving non-humans have largely involved training the subjects, so the researchers of a new study published in Biology Letters delved deeper into untrained canine number perception using fMRI. This way, they were able to go directly to the source by studying the dogs ’ brains.

For the study, 11 dogs of various breeds were trained to enter the fMRI scanner and stay still without the need for restraint or sedatives. None of the dogs had any previous training in numerosity.

Once inside the scanner, the dogs were then presented with dot arrays that varied in number but were held constant to make sure that it was the number of dots and not the size of the dots that instigated the response.

Amazingly, eight out of the 11 dogs presented greater activation of their parietotemporal cortex when the ratio between the dot arrays was more dissimilar than when the numerical values were more constant. This means that the region in dogs’ brains that responds to basic numerical qualities corresponds closely to the number-responsive regions in human brains.

“Our work not only shows that dogs use a similar part of their brain to process numbers of objects as humans do — it shows that they don't need to be trained to do it,” senior author Gregory Berns of Emory University said.

This suggests that a common neural mechanism has been conserved across mammalian evolution. Between dogs and humans, for instance, we are separated by 80 million years of evolution. According to Bern, the study presents “some of the strongest evidence yet” that numerosity has been a shared neural mechanism for at least that far back.

Unlike dogs and other animals, however, humans are capable of doing more complex math, primarily from the prefrontal cortex. According to researchers, part of the reason why we are able to do so in the first place is because of the basic ability for numerosity, which we share with other animals.

“I'm interested in learning how we evolved that higher math ability and how these skills develop over time in individuals, starting with basic numerosity in infancy,” first author and Ph.D. candidate Lauren Aulet said.