Photo by Thijs van der Weide from Pexels
Louise's daughter once asked her an interesting question while they were walking their dog. A friendly golden retriever stopped to greet a passing pug. "How does Kiefer know it's another dog?" the little girl asked. It's a good question, especially considering the enormous physical diversity of the different breeds.
According to Dr. Dominique Atier-Derian, a veterinarian at the National Veterinary School in Lyon, France, dog breeds have the greatest morphological diversity of all animal species, which means that visual recognition is a real learning challenge for each dog.
For example, compare the Great Dane, the Mastiff, the Chihuahua and the Irish Wolfhound. Given the vast differences between these breeds in size and shape, not to mention coat type, color and muzzle length, they don't even appear to be the same species. Unlike wolves, foxes or other wild dogs, domestic dogs represent enormous phenotypic diversity. With so much variation in size, shape and appearance, how do dogs recognize when interacting with other dogs?
In any social interaction, dogs must first determine if the other animal belongs to their own species. This can be done by smell, sight and hearing, but can also involve cognitive processes such as discrimination and categorization. In a recent pioneering study, Dr. Authier-Derian found that, using only visual cues, dogs can select the faces of other dogs (regardless of breed) from other animal species and group them into a category of their own.
Nine adult dogs (five male dogs and four male dogs belonging to students at the National Veterinary School) participated in this study. Two of the nine dogs were purebred (a Labrador and a Border Collie) and seven were crossbred. None of them had the same morphotype in terms of shape, color, markings, coat length and type of ears, either upright or drooping.
All dogs were between two and five years of age, had had extensive previous experience with visual interspecies and intraspecies interactions, and had received basic obedience training. They also underwent ophthalmological and behavioral examinations.
How the study worked
Dr. Autier-Derian and her fellow researchers wanted to observe whether nine dogs could discriminate any breed of dog from other animal species, including humans, and whether they could group all dogs, regardless of breed, into a single category.
The dogs were shown 144 pairs of digital color photos depicting different dogs, animals and people. The images were displayed on a pair of computer screens at the dogs' eye level. Each pair of images included the face of an unknown dog and the face of another type of animal, including a human.
The dog images spanned many pure and mixed breeds and were chosen to illustrate the wide variability of canine morphotypes, with different head shapes, coat length, color, and ear position. Non-dog photographs included humans, as well as 40 different species of domestic and wild cats, rabbits, and birds.
The dogs were trained to sit facing an experimenter in a line between two screens. On command, each dog chose between the two images in front of it by stepping into one of the screens and placing a paw in front of the selected image.
Compliance with the results
The nine dogs in the study were able to group all dog images, regardless of breed, into a single category despite the variety of breeds.
"Dogs demonstrate a very effective visual communication system, both with [species] specificity and with people," he says.
"The fact that they are able to visually recognize their own species, and that they have a high capacity for olfactory discrimination, ensures that social behavior and mating between different breeds is still potentially possible." Although humans have stretched the genus canis to its morphological limits, its biological essence is preserved."
We already know that dogs are smarter than most people think, but this study shows that they are even smarter when it comes to recognizing their own kind, whether it's a toy poodle or the Great Pyrenees.