Dogs pick out faces of other dogs, irrespective of breeds,
among human and other domestic and wild animal faces and can group them into a
category of their own. They do that using visual cues alone, according to new
research by Dr. Dominique Autier-Dérian from the LEEC and National Veterinary
School in Lyon in France and colleagues.
Their work, the first to test dogs' ability to discriminate
between species and form a “dog” category in spite of the huge variability
within the dog species, is published online in Springer's journal Animal
Individuals from the same species get together for social
life. These gatherings require recognition of similarities between individuals
who belong to the same species and to a certain group. Research to date has
shown that in some species, individuals recognise more easily, or are more
attracted by images of, individuals belonging to their own species than those
belonging to another species.
Autier-Derian and team studied this phenomenon among
domestic dogs, which have the largest morphological variety among all animal
species. Indeed, more than 400 pure breeds of dogs have been registered. The
authors explored whether this large morphological diversity presented a
cognitive challenge to dogs trying to recognise their species, when confronted
with other species, using visual cues alone.
How the study was
On a computer screen, the researchers showed nine pet dogs
pictures of faces from various dog breeds and cross-breeds, and simultaneously
faces of other animal species, including human faces. They exposed the dogs to
diverse stimuli: images of dog faces; images of non-dog species from 40
different species, including domestic and wild animals; and humans.
Overall, the dogs were shown more than 144 pairs of pictures
to select from. The authors observed whether the nine dogs could discriminate
any type of dog from other species, and could group all dogs together, whatever
their breed, into a single category.
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 dog breeds. Indeed, all nine dogs were able to group
all the images of dogs within the same category.
The authors conclude: "The fact that dogs are able to
recognise their own species visually, and that they have great olfactory
discriminative capacities, insures that social behaviour and mating between
different breeds is still potentially possible. Although humans have stretched
the Canis familiaris species to its morphological limits, its biological entity
has been preserved."