Does the dog really descend from the wolf?

Sitting comfortably on your couch, you watch your dog sleep peacefully next to you. Is he dreaming about his last bowl of croquettes? Or is he perhaps imagining the great Odyssean saga of his ancestors, where he roams the vast steppes of the last “ice age” in herds in search of the reindeer that would be their next meal?

The story of the ancestral connection between the dog (the first animal to be domesticated) and the wolf is one of the most exciting evolutionary adventures in human history. It not only makes us question the relationship we have with the rest of nature, but it also, by extension, sends us back to the question of everything we is as a human being.

Recent advances in genetics are beginning to provide key details that allow us to sketch the related history of our loyal housemates and of the proud wild dogs that are gradually repopulating our landscape.

Originally was the wolf

Today the dog (Canis familiaris) is the most widespread carnivore on the planet. It has been part of our human adventure since the time when we were still nomadic hunter-gatherers, 20,000 or even 30,000 years before the invention of agriculture.

There are almost 350 official dog breeds in the world and today there are almost 7 million in French homes. If its faithful presence by our side has long been taken for granted, the dog is nevertheless a relatively new element in human evolution. But the history and chronology of the domestication of the dog turns out to be very complex and fuels the scientific debates as much as myths or other beliefs in our society. To the question: “from what animal is the dog descended?” » most adults and children will answer without hesitation: « the wolf, of course! “Yes, but now, which wolf are we talking about here?

The Gray Wolf (Canis lupus) is an apex predator found throughout the Northern Hemisphere. In other words, the wolf is a species which is at the top of the food chain, which does not really have any natural predators, and which regulates the balance of its ecosystem through predation. Its origins are nebulous but certainly very ancient, probably dating back about 800,000 years. The Lupidae are genetically very diverse, and about forty current subspecies have already been described.

Despite the habitat and ecological niche limitations created by humans since prehistoric times, wolves are among the only large carnivores to have survived the mass extinction of the late Pleistocene (between 50,000 and 10,000 years ago), thanks in particular to their great ecological resilience and flexibility in their predatory operations. Over the last two centuries, the indirect pressure of urbanization as well as the numerous extermination campaigns have led to an almost complete disappearance of its wild forms in Europe. But in recent years, its presence is slowly recovering thanks to conservation programs. The gray wolf is currently reintroduced in our European countries together with 3 other species of carnivores: the brown bear, the boreal lynx and the wolverine.

Between dog and wolf

The timeline of prehistoric wolf domestication is probably one of the most heated debates in evolutionary science. If palaeontology obviously brings important components to this debate, the osteomorphological analyzes (the study of the size and morphology of the bones) which are able to distinguish between the proto-dogs remain difficult to identify.

Since the work of Charles Darwin, we know that a series of phenotypic changes (observable physical characteristics) are observed in animals undergoing a domestication process, at least after many generations of carefully selected traits (often favoring the most docile). Over the millennia, for example, domesticated canines have seen a reduction in the length of their snout and the size of their teeth, but also a reduction in their appendicular skeleton (fore and hind limbs). On the other hand, the isolated appearance of only one of these features on a specimen cannot prove its domesticity. Therefore, either a series of significant variables must be observed on the same individual, or this new trait must be observed repeatedly on the scale of a given population or context. The problem is that complete skeletons of Paleolithic dogs are extremely rare.

In addition to this purely osteological approach, archeology thus comes into play to strive to collect any information regarding the first direct relations between humans and canines, information that could demonstrate a special connection that had begun to be woven between these two forms of large carnivores from the Upper Paleolithic (for example, we note the use of canines to make jewelry, or its presence in parietal art). But there again it is difficult to understand the real meaning of these scanty traces.

Was the wolf the ancestor of the dog?

With the great advances that genetics has made in recent years, many studies of ancient DNA are now coming to lend a hand to paleontologists and archaeologists trying to shed light on the mystery of the origin of the “first dog.” Samples of ancient and modern dogs are now taken from every continent and the diversity of their genetic heritage is analysed. The main advantage of this method is significant: there is no need for perfectly preserved skeletons to obtain essential information, a simple bone fragment is enough. While the majority of these studies focus on mitochondrial DNA (DNA inherited only from the maternal line, but less prone to degradation), some, more rare, also relate to the complete genome (therefore on the chromosomes inherited from the maternal and the paternal line, but which is preserved much worse during fossilization).

Thanks to these findings, a framework for the global phylogenetic history of canids is beginning to take shape. And not surprisingly, these analyzes reveal a very complex demographic and phylogenetic history of the gray wolf through time. In particular, they reveal that the Paleolithic lupine populations had to adapt both to the changing geography of successive glacial events in Eurasia, but also to the human presence, which constantly changed their habitat. These environmental and ecological changes during the Quaternary period led to cycles of expansions/retractions of their populations, probably important demographic fluctuations and various fragmentations of their populations. pool genetic.

Despite this, the information from these analyzes is extremely exciting. The genetic divergence (i.e., the separation of a population into several different lineages) of modern Eurasian wolves is now estimated to have occurred about 40,000 to 20,000 years ago. This would mean that the population of these Paleolithic wolves was highly fragmented during this period, which also corresponds to the last glacial maximum (in other words, the “peak” of the ice age).

This date is all the more interesting as it coincides with the period when Homo sapiens migrates from the east and colonizes Western Europe, and where interspecific competition between large predators is strongly increasing.

More interestingly, several studies agree that all modern Eurasian wolves are descended from a single small ancestral population that probably became isolated in Beringia (northeast Siberia) during the last ice age, about 20,000 years ago, mainly to escape the great climatic instabilities that ruled the rest of Eurasia. This drastic “bottleneck” would have given rise to a new lineage, which would have then recolonized the rest of the world. This replacement of the lupine population would probably have occurred at the expense of other forms of ancient wolves, then adapted to other forms of environment elsewhere in Eurasia This is why it seems that all wolves today have a relatively “recent” common ancestor, or at least no older than the beginning of the Upper Paleolithic about 36,000 years ago.

But the story thickens with the question of the appearance of domestic dogs. The Eurasian gray wolf’s complex history stands in the way of our quest to trace the dog’s exact origins. Nevertheless, studies provide some key answers. A study of whole genome sequences of primitive Asian and African dogs, as well as a collection of samples from 19 different dog breeds from around the world, identified that the dogs of East Asia ‘Is have a genetic diversity far superior to the others. This modeling would show that the first dogs thus appeared in this region, after a divergence between the gray wolf and the domestic dog around 33,000 years ago. However, another genetic study argued in 2013 that the focus of domestication would rather have been Europe, somewhere between 32,000 and 19,000 years before the present.

Finally, a third study, unifying the first two hypotheses, suggests that the domestication of the wolf occurred independently in East Asia and Europe, before the primitive Asian dogs traveled westward with human populations, replacing the native dog population for between 14,000 and 6,400 years ago . Regardless of the hypothesis, we can remember that when we see the first traces of sedentarization and the first techniques related to agriculture appear around 11,000 years ago, there were already at least five different lineages, showing that human societies had already profoundly changed dogs . populations before the end of the Paleolithic.

And far from being divided, the co-evolution of canids has never stopped. Even today, the wolf continues to be the subject of hybridizations with other dogs, such as dogs, but also the coyote (Canis latrans), with which it is also interfertile.

In conclusion, although the determination of the geographical origin of the domestic dog and the circumstances and chronology of its domestication are still in suspense, the advances in the study of ancient DNA today offer us the means to follow the traces entangled in this past . and present canids. To the question “are dogs descended from wolves?”, the answer is therefore yes, but genetics today offers us the means to clarify: modern dogs, as varied as they are, all descend from a line of prehistoric wolves, now extinct, and would ultimately only have very distant connections with the modern wolf.