From the Dane to the Chihuahua to the Poodle to the Bulldog, the domestic dog comes in a wide variety of sizes and shapes, the result of its long relationship with humans.
Until today, we associated this great canine morphological diversity with the intensive selection carried out by breeders of the Victorian era, which, 200 years ago, led to the appearance of the notions of race pure
and pedigree so dear to the kennel clubs of the time.
However, the work of bioarchaeologist Allowen Evin, from the University of Montpellier, in France, and colleagues from academic establishments around the world brings a caveat to this theory.
Static visualization of skull shape differences between modern dogs (pink) and modern wolves (green), plotted against average morphology.
Photo : C. Brassard (VetAgro Sup/Mecadev)
By analyzing the morphology of 643 canid skulls from the past 50,000 years from specimens from North America, Europe and Asia, the researchers discovered that the first dogs already had a wide range of sizes and shapes 10,000 years ago. Their discovery was published in the journal Science (new window) (in English).
This ancient dog skull was used for photogrammetric reconstruction of 3D models during this study.
Photo: University of Exeter/C. Ameen
According to Professor David Silversides, of the Faculty of Veterinary Medicine at the University of Montreal, this surprising variety most likely shows that the first human societies already chose dogs to carry out specific tasks, such as hunting, war or guarding. We were still in the cave era,
recalls this professor, who did not participate in the study.
Thus, the breeding programs of the Victorian period would not have had the influence that is attributed to them.
The extreme diversification of today’s dogs was thought to come from this era, because modern breeds have solidified in closed genetic boxes, where reproduction occurs exclusively between animals of the same group.
This current dog skull was used for photogrammetric reconstruction of 3D models during this study.
Photo: University of Exeter/C. Ameen
The team also analyzed skulls of ancient wolves, and the results showed that they were morphologically more varied than modern wolves. This characteristic was most likely transmitted to the first domesticated canids, who are their descendants
think the authors of the work.
The strength of this study lies in the high number of samples and their overall distribution, which is rare compared to studies limited to particular archaeological sites.
There is still a weakness in this work. To calibrate the morphometric criteria, the researchers used many more modern wolves than ancient wolves.
observes the researcher. The authors recognize this, but they had no choice, since there are only 17 ancient wolf skulls.
Very old fragmentary bones often require indirect dating, for example through human-made objects found near the bones
specifies Professor Silversides.
A dog’s paw rests on a human hand. (Archive photo)
Photo : Getty Images
Domestication, a complex process
Scientists agree on one fact: dogs and wolves descend from a common ancestor, a species of gray wolf that is now extinct.
The timing of dog domestication remains unclear and is still the subject of debate.
It is almost impossible to determine the exact time and place, especially since this long process probably took place more than once and in several places
says Professor Silversides.
To complicate the work of scientists, there is a gap between the dating obtained with classic morphological studies (like this one) and genetic studies based on DNA. The former tend more towards 11,000 years ago, while the latter date back to 25,000 or 30,000 years ago.
In addition, it is difficult to identify the first dogs based on their morphology alone sinceit is very possible that they preserved wolf-type skulls for several generations
notes David Silversides.
The authors of this work nevertheless established that the oldest distinctly canine skull they studied dates back around 11,000 years.
According to them, other older skulls do not display the distinctive physical characteristics of the domestic dog (A family dog).
However, this interpretation is not unanimous, since several of these bones have already been associated with the dog in the past by other teams.
Several factors could have led to the rapid diversification of the first dogs. It may have emerged as dogs adapted to different environments and diets and as they moved to new areas during human migrations.
Moreover, an analysis of the genome of 73 ancient dogs, (new window) published in the same edition of the journal Scienceshows that ancient dogs accompanied ancient hunter-gatherer humans as they moved from Eastern Europe to Eastern Siberia.
Still a lot of questions
Professor Silversides believes more specimens need to be unearthed from the period between 30,000 and 11,000 years ago.
It is absolutely necessary to succeed in reducing the temporal gap between classic morphological data and genetic data.
The authors of the study, for their part, believe that more research is needed to explain the evolution of certain wolf-like morphological characteristics conserved within specific breeds, for example the German shepherd.
Did you know?
- No less than 359 breeds of domestic dogs are recognized by the Fédération cynologique international (FCI). Others have a provisional title before they obtain final status. This number is constantly changing.
- These breeds are classified into 10 groups based on their function or type (sheepdogs, terriers, greyhounds, etc.).
National clubs, for exampleAmerican Kennel Club or the British Kennel Club, have their own lists, which may vary from that of the FCI. For example, the Kennel Club recognizes nearly 450 breeds.
