Chernobyl's stray dogs are 'genetically distinct' 40 years after the massive nuclear radiation leak, scientists find

• Dogs at the Chernobyl nuclear power plant are "genetically distinct" from those living farther away.
• Scientists finished the first genetic analysis of stray dogs at the nuclear disaster site and nearby Chernobyl City.
• The data could help to reveal the long-term effects of radiation exposure.

Almost 40 years after the nuclear disaster in Chernobyl, hundreds of feral dogs still live in the abandoned area surrounding the ruins of the Ukrainian power station.

The canine population is now the focus of a scientific study, which is probing their genetic makeup to see what it reveals about living in a radioactive environment.

So far it's not clear whether nuclear radiation is the culprit, but there's definitely something different about the Chernobyl dogs.

In a new report published last week in the journal Science Advances, scientists found dogs living around the old nuclear power plant are "genetically distinct" from those living farther away from the disaster's epicenter.

While these results do not show that radiation is undoubtedly what caused these genetic differences, the data could help better understand the long-term effects of radiation exposure. This first analysis of the dogs' genomes paves the way for researchers to hunt down particular genetic mutations, which could help scientists understand how humans might respond to radiation exposure.

"Do they have mutations that they've acquired that allow them to live and breed successfully in this region?" Elaine Ostrander, a dog genomics expert and a senior author of the study, told The New York Times. "What challenges do they face and how have they coped genetically?"

Chernobyl dogs survived nuclear disaster and a killing campaign

The abandoned and radioactive Chernobyl Exclusion Zone is about the size of Yosemite National Park, and it's similarly full of animals, including elk, deer, beavers, wolves, bison, and wild boar.

None of those creatures lead lives so human-adjacent as dogs, though. Scientists are curious about how radiation has affected wildlife around Chernobyl, but the dogs' DNA samples are highly valuable, because they often share the same spaces and diets as humans, Ostrander told Nature.

"We've never had an opportunity to do this work in an animal that reflects us as well as dogs," she said.

The hundreds of dogs surrounding Chernobyl started out as pets. When the Soviet power plant exploded in 1986, residents who evacuated the area were forced to leave them behind.

While authorities at the time culled many animals to stop radioactive contamination from spreading, clean-up workers cared for some dogs, according to New Scientist.

The Dogs of Chernobyl Research Initiative — which also provides veterinary care to the strays — estimates that more than 800 feral dogs are living in the area.

"You have this region where there's different levels of radioactivity, there's dogs living everywhere," Ostrander said. "We had to know who was who and what was what before we could begin our hunt for these critical mutations."

15 families of dogs with German shepherd DNA

The team of researchers collected blood samples from 302 dogs representing three distinct "free-roaming dog populations."

About half of the dogs lived within the power plant itself, while a similar number lived in Chernobyl City, about nine miles away. A small number of the dogs lived in Slavutych, 28 miles away.

The genetics revealed 15 families of dogs, with pooches around the power plant quite different from those in Chernobyl City. The two populations didn't appear to interbreed very much, even though some families covered wide areas of land.

Both groups shared DNA with German shepherds, as well as some Eastern European shepherds. In future research, scientists can look for mutations by comparing the Chernobyl dogs' DNA with that of German shepherds.

It will be difficult to differentiate between which genetic changes are caused by radiation and which are caused by "other influencing factors" like physical isolation, according to the researchers.

Even so, Ostrander told The Associated Press that this is a "golden opportunity" to start to answer the question: "How do you survive in a hostile environment like this for 15 generations?"

If radiation caused mutations in the power-plant dogs' unique genetics, that begs another question: Are today's Chernobyl dogs being affected by lingering radiation? Or are they inheriting radiation-altered genes from earlier generations of Chernobyl dogs?

The researchers are going full-steam ahead to find out. According to the AP, Ostrander's team was just at Chernobyl in October working on follow-up research with some of the world's most unique dogs.

This story has been updated. It was originally published on March 5, 2023.