Dogs process numbers in a similar way to humans, with brain scans revealing that both man and his best friend use the so-called parietotemporal cortex to count.
Researchers in the US are the first to train dogs to voluntarily enter a brain scanner and remain still while their neural responses were recorded.
The findings add to evidence suggesting that a common brain mechanism for rapid counting has been maintained across the evolution of mammals.
Psychologists Lauren Aulet, Gregory Berns and Stella Lourenco of Emory University in Georgia, US and colleagues trained 11 dogs of various breeds to lie still in a functional magnetic resonance imaging scanner.
The team then analysed which areas of the brain lit up as the canines responded to varying numbers of dots that were displayed on a screen.
None of the dogs had received any advanced training in numerosity — that is, the basic sensitivity to numerical information.
Eight of the canines showed a greater level of brain activity in the parietotemporal cortex when the number of dots on the screen increased or decreased than when the number of dots remained the same.
The parietotemporal cortex is the same region of the brain that responds to numbers in humans.
‘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,’ said Professor Berns.
‘Understanding neural mechanisms — both in humans and across species — gives us insights into both how our brains evolved over time and how they function now,’ added Professor Lourenco.
To ensure that the dogs were responding to the changing number of dots — and not their overall size — the team made sure that the total area of dots displayed was always constant.
The brain’s capacity to quickly estimate the number of objects in a scene — such as, for example, the amount of food available to be foraged or the number of approaching predators — is known as the ‘approximate number system’.
Previous studies have suggested that humans primarily draw on their parietal cortex for this ability, which is present even in infancy.
Numerosity is a widespread ability throughout the animal kingdom — and does not appear to depend on a capacity for symbolic thought.
The present study expands on previous work with non-humans, however, with past work having typically relied on the use of subjects that had been trained in numerosity.
‘We went right to the source, observing the dogs’ brains, to get a direct understanding of what their neurons were doing when the dogs viewed varying quantities of dots,’ said Ms Aulet.
‘That allowed us to bypass the weaknesses of previous behavioural studies of dogs and some other species.’
Humans and dogs are separated by 80 million years of evolution, Professor Berns noted.
‘Our results provide some of the strongest evidence yet that numerosity is a shared neural mechanism that goes back at least that far,’ he added.
Unlike dogs and other animals, however, humans can build on basic numerosity in order to perform more complicated maths — a skill that draws upon our prefrontal cortices.
‘Part of the reason that we are able to do calculus and algebra is because we have this fundamental ability for numerosity that we share with other animals,” said Ms Aulet.
‘I’m interested in learning how we evolved that higher mathematical ability and how these skills develop over time in individuals, starting with basic numerosity in infancy.’
The full findings of the study were published in the journal Biology Letters.
IS DOG INTELLIGENCE AKIN TO HUMAN INTELLIGENCE?
Dogs’ abilities to learn are varied, much like humans’ abilities, according to WebMD.
Dogs that were bred in order to hunt, retrieve or herd are faster learners because they are inherently quicker on their feet.
Similarly, dogs bred to guard livestock or track scents are usually slower.
The key in training your dog, WebMD says, comes down to knowing what your dog was bred to accomplish.
However, all dogs can be trained to follow simple commands, according to trainers.
WebMD reports that the following are the most naturally intelligent dog breeds:
- Border Collie
- German Shepherd
- Golden Retriever
- Doberman Pinscher
- Shetland Sheepdog
- Labrador Retriever
- Australian Cattle Dog
SOURCE: Daily Mail, Ian Randall