Between 15,000 and 30,000 years ago, a now-extinct population of wolves evolved into dogs, with a little help from humans. Today—at least in Italy, which hosts one of Europe’s largest wolf populations—genes are flowing in the opposite direction. Recent genetic testing suggests that, particularly in the country’s central and southern regions, nearly half of the wild wolves (Canis lupus) are actually wolf-dog hybrids.
That represents a massive shift from the 1970s, when Luigi Boitani, now the chair of the International Union for Conservation of Nature’s Large Carnivore Initiative for Europe, discovered the country’s first known wolf-dog hybrid.
The 1970s were a period of transition for Italy’s wolves. At the time, the population was coming out of a tailspin. New laws and conservation efforts were designed to encourage wolves to recolonize habitat from which they’d been extirpated. But the landscape, and its inhabitants, had changed. Wild countryside had given way to rampant urbanization, and Italy’s central and southern regions—where wolves began recovering first—hosted high numbers of free-ranging dogs. It didn’t take long for the wolves to begin rubbing shoulders (and more) with the local canines.
Decades later, Rita Lorenzini, a biologist and director of Italy’s Experimental Zooprophylactic Institute of Lazio and Tuscany, worked with her team to analyze hundreds of DNA samples collected from a region spanning from Bologna down to the toe of Italy’s boot. Their analysis, published in January in the journal Biological Conservation, reveals just how close the two canid species have become.
Lorenzini’s research looked at genetic material collected from 748 wolves that had been found dead between 2020 and 2024, and 26 more that had been collected between 1993 and 2003. The team found that 47 percent were wolf-dog hybrids. And while some of these animals are the descendants of hybridization events that took place generations ago, others are more recent crosses, showing that hybridization is still occurring.
Hybrids are not easy to spot. While some people suggest wolf-dog hybrids have distinctive physical features, such as darker fur than non-hybrid wolves, Paolo Ciucci, a biologist at Sapienza University of Rome who worked with Lorenzini on the recent study, says scientific evidence of these visual differences is lacking and that genetic analysis remains the most reliable way to identify a hybrid.
But the extremely high presence of wolf-dog hybrids in central and southern Italy, Ciucci says, represents a threat to the future of the country’s wolves.
It’s unlikely that a wolf living in a healthy, stable pack in the wild would reproduce with a free-ranging dog, Ciucci explains. Those wolves are more likely to see a dog as competition, or even as prey. But when the pack structure falls apart and female wolves find themselves alone in an area filled with free-ranging dogs, the dynamic can change.
While Italy hosts nearly 3,300 of Europe’s roughly 21,500 wolves, the fact that so many are actually dog hybrids poses a silent danger, Ciucci says. Italy’s wolves might be close to a point of no return that experts call “genetic swamping,” in which the wolves’ original gene pool is irreversibly replaced by that of the hybrids. In simple words, it means the wolf—genetically speaking—could disappear.
In northern Italy, where there are fewer free-ranging dogs, wolf-dog hybrids are much rarer than in the central and southern regions of the country. But that, Lorenzini says, is likely temporary. Wolves can cross vast distances, and hybrids could eventually mix and mingle with wolves in northern Italy, or even across Europe.
Of course, wolves and domesticated dogs have been breeding—and thus hybridizing—since they first diverged thousands of years ago. In North America, for example, gray wolves with black coloring are believed to be the distant descendants of wolf-dog mixes. Research suggests these canines even picked up some perks from their interspecies mingling. Black wolves are in fact more resistant than their peers to some diseases, such as canine distemper, and they may also be more successful at hunting in forests.
Approximately 5,500 wolves roam the Lower 48 states, with another 8,000 to 11,000 in Alaska.
But what’s happening in Italy is totally different, Lorenzini says, because of the scale and the speed at which it is taking place.
Astrid Vik Stronen, a geneticist at the University of Ljubljana in Slovenia who wasn’t involved in the research, agrees the possible downsides of hybridization outweigh the potential benefits. “Overall,” she says, “I think the main concern is that it would be a risk.”
Italy’s abundance of wolf-dog hybrids, Ciucci adds, threatens to disrupt the key role wolves play in the ecosystem. Though researchers know little about the ways hybridization affects how wolves function, as it’s difficult to study the animals in the wild, Ciucci says it’s possible that hybridization is driving changes to their physiology and behavior—such as how they hunt, how they find and defend their territory, and how they interact socially.
To Ciucci, the rampant hybridization is also putting the uniqueness of the species at risk. “The authenticity of the wolf species [is going] missing, with all its cultural, ecological and evolutionary value.”
This is something Boitani has been worried about—and has been persistently warning about—since he discovered that first hybrid decades ago. “Perhaps because I’m a bit old fashioned,” Boitani says, “and because I’m attached to the idea of the wolf as I’ve always known it, dreamed it and experienced it … [but] I oppose the idea that, tomorrow, all Italian wolves will be naturally hybrids.”
This story originally appeared in bioGraphic, an independent magazine about nature and regeneration powered by the California Academy of Sciences.
