For generations of dogs, the radioactive remains of the Chernobyl nuclear power plant have been home.
During the first genetic analysis of these animals, scientists discovered that dogs living in the industrial area of the power plant are genetically different from dogs living further away.
Although the team could distinguish between dog populations, the researchers did not point to radiation as the cause of any genetic differences. But future research, based on findings published on March 3 in Science Advances, can help reveal how a radioactive environment leaves its mark on animal genomes.
This could have implications for other nuclear disasters and even for human spaceflight, says Timothy Musso, an evolutionary ecologist at the University of South Carolina in Columbia. “We really hope that what we learn from these dogs … will be useful for understanding the impact on humans in the future,” he says.
After his first trip in 1999, Musso stopped counting how many times he had been to Chernobyl. “I lost track after we hit about 50 visits.”
He first met Chernobyl’s semi-feral dogs in 2017 on a trip with Clean Futures Fund+, an organization that provides veterinary assistance to the animals. Little is known about how local dogs survived the accident at the nuclear power plant. In 1986, an explosion at one of the power plant’s reactors triggered a catastrophe that sent a huge amount of radioactive isotopes into the air. Contamination from the plant’s radioactive plume has largely settled nearby, in a region now known as the Chernobyl Exclusion Zone.
Since the disaster, dogs have been living here, which are fed by liquidators of the consequences of the accident at the Chernobyl nuclear power plant and tourists. About 250 vagrants lived in and around the power plant, among spent fuel reprocessing plants and in the shadow of the destroyed reactor. Hundreds more roam further into the exclusion zone, an area roughly the size of Yosemite National Park.
During Musso’s visits, his team collected blood samples from these dogs for DNA analysis, allowing researchers to determine the dogs’ complex family structure. “We know who is related to whom,” says Elaine Ostrander, a geneticist at the National Human Genome Research Institute in Bethesda, Maryland. “We know their heritage.”
Dog packs aren’t just a pack of wild, feral dogs, she says. “In fact, families of dogs breed, live and exist at the power plant,” she says. “Who would have imagined?”
The team reports that dogs in the exclusion zone share common ancestry with German shepherds and other sheep breeds, as do many other free-breeding dogs from Eastern Europe. And while their work showed that dogs in the area of the power plant are genetically different from dogs in Chernobyl City, about 15 kilometers away, the team doesn’t know if the radiation caused those differences, Ostrander says. Dogs can be genetically different simply because they live in a relatively isolated area.
The new discovery is not so surprising, says Jim Smith, an ecologist at the University of Portsmouth in England. He was not involved in the new study, but has worked in the field for decades. He worries that people might assume that “radiation has something to do with it,” he says. But “there is no evidence for this.”
Scientists have spent decades trying to determine how the radiation at Chernobyl affected wildlife. “We studied the effects on birds, rodents, bacteria and plants,” Musso says. His team found animals with increased mutation rates, shortened life spans and early onset of cataracts.
Smith says that it is difficult to single out the effects of low doses of radiation among other factors. “[Ці дослідження] are so difficult … there are many other things going on in the natural environment.” What’s more, animals may benefit in some way when people leave contaminated areas, he says.
According to Ostrander, the team is now studying how and if radiation damage accumulates in the dogs’ genomes. Knowing the dogs’ genetic background will make it easier to spot any radioactive flags, says Bridget von Holdt, an evolutionary geneticist at Princeton University who was not involved in the work.
“I think it’s cool,” she says. “I want to know more.”