What is the first look at the genetics of the Chernobyl Dogs?

For generations of dogs, it is home to the radioactive remains of the Chernobyl Nuclear Power Plant.

In the first genetic analysis of these animals, scientists discovered that the dogs living in the industrial power plant were genetically distinct from the dogs working farther away.

Although the team was able to distinguish between dog populations, the researchers did not point to radiation as the cause of any genetic differences. Future studies, which build on the findings, were reported on March 3 Journal of Sciences: to help discover how radioactive environments leave their mark on animal genomes.

That could have implications for other nuclear disasters and even human space travel, says Timothy Mousseau, an evolutionary ecologist at the University of South Carolina in Columbia. “We have high hopes that what we learn from these dogs … will be useful for understanding human exposures in the future,” he said.

Since his first trip in 1999, Mousseau has stopped counting how many times he has been to Chernobyl. “I lost track after hitting about 50 visits.”

He first discovered the semi-feral dogs of Chernobyl in 2017, on a trip with the Clean Futures Fund +, an organization that provides veterinary care to animals. Not much is known about how local dogs survived after the nuclear accident. In 1986, the explosion of one of the power plant’s reactors triggered a disaster that released huge amounts of radioactive isotopes into the air. Contamination from the radioactive cloud of the plant settled nearby, in a region now called the Chernobyl Exclusion Zone.

Dogs lived in the area after the disaster, fed by Chernobyl clean-up workers and tourists. Some 250 vagrants lived in and around the power plant, among the power facilities and in the shadow of the destroyed reactor. Hundreds more roam in the exclusion zone, an area roughly the size of Yosemite National Park.

During Mousseau’s visits, his team collected blood from these dogs for DNA analysis, which the researchers described as the dog’s complex family structure. “We know who’s related to who,” says Elaine Ostrander, a geneticist at the National Human Genome Research Institute in Bethesda, Md. “We know their heritage.”

“Canine packs aren’t just mash for feral dogs,” he said. “Dogs are actually family, living in the grass potential,” he said. “Who would have thought?”

The dogs within the exclusion zone have shared ancestry with German shepherds and other shepherds, as do many other free-breeding dogs from Eastern Europe, the team reports. And although their work revealed that the dogs in the potential grass area look quite different from the dogs in the city of Chernobyl, about 15 kilometers away, the team doesn’t know whether the radiation caused these differences or not, Ostrander says. Dogs can be distinguished by race simply because they live in a relatively isolated area.

The new finding is not so surprising, says Jim Smith, an environmental scientist at the University of Portsmouth in England. It was not a new study, but he had been working in this field for decades. He’s worried that people will assume “there’s something radical to do with it,” he says. But there is no evidence of that.

Scientists have been trying to figure out how radiation exposure at Chernobyl affected wildlife for decades (SN: 5/2/14). “We looked at the consequences of birds and moles and bacteria and plants,” Mousseau says. His team found animals with elevated rates of mutation, shortened life spans and discovered cataracts.

It’s not easy to miss the effects of low-dose radiation, among other factors, says Smith. “[These studies] they are so difficult … there’s lots of other stuff going on in the real world. “Also, animals can get some benefits when people leave contaminated zones,” he says.

How, or if, radiation damage is accumulating in canine genomes is something the team is looking at now, says Ostrander. Knowing the genetics of local dogs makes it easier to spot any red flags, says Bridget vonHoldt, an evolutionary geneticist at Princeton University who was not involved in the work.

“I feel like it’s too early,” he said. “I want to know more.”