It happened thousands of years ago, and it may be happening again: Wolves in various parts of the world may have started on the path to becoming dogs. That’s the conclusion of a new study, which finds that the animals are increasingly dining on livestock and human garbage instead of their wild prey, inching closer and closer to the human world in some places. But given today’s industrialized societies, this closeness might also bring humans and wolves into more conflict, with disastrous consequences for both.
“It’s a thought-provoking study, and does a good job of laying out how diet has the potential to change a large predator,” says Lee Dugatkin, an evolutionary biologist at the University of Louisville in Kentucky, who wasn’t involved in the research.
To find out how gray wolves might be affected by eating more people food, Thomas Newsome, an evolutionary biologist at the Deakin University in Melbourne, Australia, and his colleagues examined studies of what’s happened to other large carnivores that live close to people. Asiatic lions in the Gir protected area of western India, for instance, primarily kill and eat livestock, and have grown so much less aggressive toward humans that tourists can visit them on foot. In Israel, red foxes live longer and use smaller home ranges when they rely on a diet of leftovers. In contrast, black bears in North America that dine on human garbage are more likely to die young—because people kill them.
Newsome’s 2014 study of a dingo population in Australia’s Tanami Desert showed that the wild dogs’ habit of dining almost exclusively on junk food at a waste management facility had made them fat and less aggressive. They were also more likely to mate with local dogs and had become “cheeky,” says Newsome, daring to run between his legs as he set out traps for them. Most intriguingly, the dumpster dingoes’ population formed a genetic cluster distinct from all other dingoes—indicating that they were becoming genetically isolated, a key step in forming a new species.
Is this happening to gray wolves? The conditions are ripe for it, says Newsome, noting that human foods already make up 32% of gray wolf diets around the world. The animals now mostly range across remote regions of Eurasia and North America, yet some are returning to developed areas. Wolves in Greece primarily consume pigs, goats, and sheep; those in Spain feed mainly on ponies and other livestock; and Iranian wolves rarely eat anything other than chickens, domestic goats, and garbage. “Based on what’s happened to these other carnivores [that eat human foods], we think these wolves will change,” Newsome says.
The wolves’ new diet could affect everything from the size of their packs to their social behaviors, the team reports today in Bioscience. Like the dingoes, these wolves will probably mate with more dogs and, in North America, with coyotes, the researchers say. Newsome expects that they will also begin to diverge genetically from prey-hunting wolves, just as the dumpster dingoes did. Because ancient wolves are believed to have evolved into dogs by eating food and garbage at human camps, we may also be seeing “the makings of a new dog” today, hypothesizes Newsome, who plans to begin testing his idea with wolves in Washington state.
Not everyone is convinced. “I doubt if we’re domesticating wolves that eat human-sourced food,” says Robert Wayne, an evolutionary biologist and expert on canine genetics at the University of California, Los Angeles. “That diet is more likely to get them killed.” Unlike the trash-picking dingoes, which reduced their territories, wolves still range so widely that garbage-eaters are less likely to become genetically isolated from the rest of their population, he says. Bobcats, coyotes, and other animals that are already well-integrated in our neighborhoods are more likely to become domesticated, he adds.
Wayne and Newsome agree that for all these species, the best outcome isn’t domestication, but restoration of their habitats and natural prey in places where they can avoid people, livestock, and trash. If humans can arrange that, we won’t have a new dog, Newsome says. But we’ll still have wolves.