- Fifteen puppies rescued from Chernobyl in 2018 were adopted by American families, sparking decades-long research into whether radiation exposure created genetically distinct dogs at the nuclear disaster site.
- Researchers studying 302 dogs at Chernobyl found genetic differences between power-plant and city dogs, but couldn’t conclusively prove radiation caused harmful mutations that could pass to future generations.
- Scientists remain divided on whether radiation explains the dogs’ genetic changes, with some suspecting natural selection and others pointing to ancestry, diet, and disease as alternative explanations for the observed differences.
In 2018, 15 puppies from Chernobyl went to live with American families, according to SPCA International. They’d been rescued from the Chernobyl nuclear power plant, the site of the 1986 reactor explosion that spread radioactive material across much of Europe. Decades later, stray dogs still lived among the crews who come in on shifts to contain and dismantle the plant, eating scraps people saved for them.
In 2023, researchers from the National Human Genome Research Institute, the University of South Carolina, and other institutions published a genetic study of 302 dogs living at the plant and in nearby communities. The power-plant dogs were genetically distinct from those living in Chernobyl City, roughly 10 miles away. Researchers wanted to know whether radiation exposure could help explain those differences.
That possibility turned the research into a mega-viral story: are the dogs of Chernobyl really experiencing rapid evolution?
Well, sort of. Timothy Mousseau, an evolutionary biologist at the University of South Carolina and a coauthor of the dog studies, says what’s happening is pretty straightforward. “Evolution simply means change,” says Timothy Mousseau, an evolutionary biologist at the University of South Carolina and a coauthor of the dog studies. And change doesn’t necessarily leave an animal healthier or better equipped to survive.
The more interesting question may be whether a puppy born far from the power plant can inherit damage from an accident it never lived through. “Immigrant dogs from Chernobyl could carry these deleterious mutations to other populations where the effect would be negative,” Mousseau says.
But that scenario depends on whether radiation caused those mutations in the dogs, and whether any dogs able to reproduce actually left the zone.
SPCA International said it would spay or neuter the puppies before sending them to their new homes. Assuming those procedures went ahead, none could have offspring. For the possibility Mousseau describes, a dog would have to leave Chernobyl and have puppies elsewhere.
Since the breakthrough Chernobyl dogs discovery, the research has taken several turns. In another 2023 study, published in Canine Medicine and Genetics, the dogs’ DNA was examined for signs of natural selection. They found hints that dogs with certain genetic variants may have been more likely to survive and have puppies, passing those variants on. What gave those dogs an advantage, and whether radiation played a part, remained unclear.
A 2024 study published in PLOS One found no evidence that the power-plant dogs had accumulated more mutations than the city dogs. Mousseau, a coauthor of that paper, still suspects that mutations occur more often in dogs exposed to contamination. He bases that suspicion on studies of other Chernobyl organisms, though his team didn’t find that pattern in the dogs.
A September 2026 study in Genes, meanwhile, found more signs of natural selection in the power-plant dogs. Dogs with certain genetic variants may have been more likely to survive and have puppies, even if those variants existed long before the accident. Radiation didn’t have to create new mutations for that to happen, and the study couldn’t establish whether radiation gave those dogs an advantage.
Jim Smith, a professor of environmental science at the University of Portsmouth who studies radioactive contamination, remains skeptical that radiation explains the findings. The populations also differ in ancestry, breeding history, diet, disease exposure, and contact with other contaminants.
“There is no evidence in the lab to suggest that the dose rates to dogs are high enough to significantly influence natural selection,” he says.
Both researchers reject the claim that these dogs are proven radiation-resistant mammals. On the other hand, the scientists differ over whether radiation is likely to have increased mutation rates, and how much field research can ultimately establish. Smith thinks that convincingly separating radiation from all the other differences in a natural population is “extremely difficult, and in practice, I think impossible.” In his view, scientists have a better chance of getting an answer in a lab, where they can control radiation exposure and what the animals eat.
Mousseau is pursuing comparisons across contaminated sites. His team is studying dogs in the Marshall Islands, whose ancestors encountered fallout from nuclear testing in the 1940s and 1950s, and also around the former Soviet testing ground at Semipalatinsk, in Kazakhstan. More than 450 nuclear tests took place at that site.
The goal is to compare dogs from separate places that share similar histories of radioactive exposure. Repeated genetic changes across those populations could give researchers stronger leads to investigate. Mousseau says those analyses are still underway.
Mousseau worries less about obvious damage than about mutations subtle enough to travel—ones that leave a dog less healthy without stopping it from breeding. He suspects some might raise cancer risk or interfere with immunity or growth, though that hasn’t been demonstrated in these dogs. If it ever is, a dog born hundreds of miles from the plant could carry health problems from an accident it never experienced.
Confirming that would mean tracking several generations to see which dogs inherited a mutation and whether they developed health problems more often than those that didn’t. No radiation reading can answer that. And for the families who adopted the puppies, an inherited mutation isn’t contagious—it can’t spread through petting, feeding, or sharing a home.
Tracking generations of dogs isn’t a new idea. Decades before Chernobyl, scientists were doing it on purpose. During the Cold War, scientists deliberately exposed domestic dogs to radiation, mostly in American experiments. A 2021 review by Mousseau, Elaine Ostrander, and Gabriella Spatola catalogs decades of those experiments and what they revealed about cancer, fertility, and immune function. The experiments produced extensive disease records, Mousseau says, but the researchers lacked today’s genetic tools.
By contrast, Mousseau’s team can now study the dogs’ DNA for clues to how radiation affected their health. He sees a reason to look beyond dogs, too. They get many of the same diseases we do, sometimes because of the same genetic changes.
Chernobyl now looks, from a distance, like a recovery story. Smith attributes much of Chernobyl’s ecological rebound to the retreat of farming, forestry, hunting, and development—a recovery, he stresses, that “emerged from a human tragedy.” But animals returning to a landscape can’t tell us what happened inside their cells.
For that, Mousseau is going back to the DNA, with what he calls “perhaps 150 additional data points.” The question he wants to settle is whether the mutations arose soon after the accident, or accumulated over the decades since. Counting carriers won’t answer that question, since an early mutation that helped dogs survive could have swept quickly through a small population, while a newer one might turn up in only a few animals. But a closer look at the genome could estimate a mutation’s age, and whether it predates the nuclear reactor meltdown.
“Hopefully we’ll have answers in the coming year or two,” he says. Their DNA might let scientists trace a mutation back to a dog that survived the accident, long before anyone thought to take its blood.
Eric Spitznagel is a frequent contributor to magazines like Playboy, Esquire, and the New York Times, and was employed for over two decades by the Second City comedy theater, where Stephen Colbert was his Secret Santa _twice.