Dogs can pick out faces of other dogs on a computer screen, say researchers, irrespective of breed, showing they can recognize and categorize their own species by sight alone.
They can distinguish the faces from those of humans and other domestic and wild animals to form a 'dog' mental category, say researchers at the LEEC and National Veterinary School in Lyon in France and colleagues.
"The fact that dogs are able to recognize their own species visually, and that they have great olfactory discriminative capacities, insures that social behavior and mating between different breeds is still potentially possible," says the team.
"Although humans have stretched the Canis familiaris species to its morphological limits, its biological entity has been preserved."
Domestic dogs have the largest morphological variety among all animal species - indeed, more than 400 pure breeds of dogs have been registered. So can they recognize one another using visual cues alone?
On a computer screen, the researchers showed nine pet dogs pictures of faces from various dog breeds and cross-breeds, along with faces of other animal species, including humans. The pictures included images of dog faces, images of non-dog species from 40 different wild and domestic species and humans. Overall, they were shown more than 144 pairs of pictures to select from.
And the results suggest that dogs can form a visual category of dog faces and group pictures of very different dogs into a single category, despite the diversity in breeds. Indeed, all nine dogs were able to do this quite compfortably.