There’s Something Odd About the Dogs Living at Chernobyl

In the spring of 1986, in their rush to flee the radioactive plume and booming fire that burned after the Chernobyl power plant exploded, many people left behind their dogs. Most of those former pets died as radiation ripped through the region and emergency workers culled the animals they feared would ferry toxic atoms about. Some, though, survived. Those dogs trekked into the camps of liquidators to beg for scraps; they nosed into empty buildings and found safe places to sleep. In the 1,600-square-mile exclusion zone around the power plant, they encountered each other, and began to reproduce. “Dogs were there immediately after the disaster,” says Gabriella Spatola, a geneticist at the National Institutes of Health and the University of South Carolina. And they have been there ever since.

Spatola and her colleagues are now puzzling through the genomes of those survivors’ modern descendants. In identifying the genetic scars that today’s animals may have inherited, the researchers hope to understand how, and how well, Chernobyl’s canine populations have thrived. The findings could both reveal the lasting tolls of radiation and hint at traits that have helped certain dogs avoid the disaster’s worst health effects. The fates of dogs—bred and adapted to work, play, and lounge at our side—are tied to ours. And the canines we leave behind when crises strike could show us what it takes to survive the fallout of our gravest mistakes.

One of the key canine groups the team is focusing on is based at what’s left of the power plant itself, and has likely weathered the highest levels of radiation of any dog population in the exclusion zone. The researchers are working to compare the genomes of those dogs with those of others living farther out, in Chernobyl City, a quasi-residential region about nine miles away that was evacuated after the blast, and in Slavutych, a less contaminated city roughly 30 miles out, where many power-plant workers settled after leaving their post.

The spatial differences are essential to the study’s success. The region’s landscape is “a patchwork of different radioactivity levels,” says Timothy Mousseau, a biologist at the University of South Carolina who’s been studying Chernobyl’s wildlife for more than 20 years, and is co-advising Spatola’s work. Which means that geographically distinct packs of dogs could, in theory, have distinct exposure histories, and distinct genetic legacies to show for it. The team’s work is just beginning. But in the hundreds of blood samples that Spatola and her colleagues have analyzed from dogs in all three groups, they’ve already found evidence that the reactor-adjacent canines are different in at least some ways.

The animals that the team sampled in Chernobyl City and Slavutych, the researchers found, look a lot like dogs you’d find elsewhere. They’ve been born of mixtures of modern breeds: mastiffs, pinschers, schnauzers, boxers, terriers. But the power-plant population seems more stuck in the past. The dogs there are far more inbred, and still skew heavily German shepherd—a breed that has a long history in the region, a hint that the animals have largely kept to their ancestral roots, says Elaine Ostrander, a geneticist at the National Institutes of Health and another of Spatola’s co-advisers. This pack might represent something like “a time capsule” from the disaster’s worst days, says Elinor Karlsson, a genomics expert at the Broad Institute of MIT and Harvard. Perhaps this lineage of dogs has been stewing in the plant’s radiation for a dozen generations or more. Some may even have inherited mutations caused by the explosion itself.

The long-ranging consequences of their exposures, though, aren’t yet clear. Repeated, heavy doses of radiation—which can mutate DNA, seed cancers, and irreparably damage the structural integrity of cells—can be, without question, “extremely detrimental to life,” says Isain Zapata, a biomedical researcher at Rocky Vista University. And over the decades, a wealth of studies has revealed serious health effects among some local animals: Birds have been found with tumors and unusually small brains; bank voles have battled cataracts and produced wonky, underperforming sperm. Even bees seem to struggle to reproduce. Still, not all creatures are equally susceptible to radiation; many have also avoided the region’s most saturated zones. And in some parts of the exclusion zone, some of them appear to be flourishing on terrain now largely devoid of humans and their polluting, disruptive ways. In this landscape of possibilities, it’s hard to say where the dogs of Chernobyl might fall: Domestic canines depend heavily on us, and may suffer more than other animals when we leave. But that dependence also means that dogs are also less likely to chow down on wild, radiation-contaminated food, and may be well positioned to take advantage of the ruins we leave behind—and to mooch more when we start to creep back.

Read: The creatures that remember Chernobyl

What the team finds next will be telling. Scientists have already spent decades scrutinizing canine genomes; a reference book for what’s “typical” already exists, which makes detecting “when something’s unusual” much easier, Karlsson told me. The researchers might uncover mutations and sickness in the power-plant pack—a sign that the dogs’ genomes have been walloped by years of radiation, as those of some other animals apparently have. But Karlsson also thinks the team could find the opposite: hints of genetic traits that have kept the dogs alive under harsh conditions, such as a higher resistance to cancer. That, in turn, could bode well for us. Canine and human genomes are quite similar, and “domestic dogs have been a model for human cancer for a very long time,” says Shane Campbell-Staton, an evolutionary biologist at Princeton who studies Chernobyl’s wolves. Perhaps these dogs did not bend under pressure, but instead thrived.

One of the trickiest parts of the project will be figuring out which differences among the studied dog groups are attributable to radiation, rather than the ways in which the Chernobyl disaster completely remodeled the region and its ecosystems. Populations of plants, insects, birds, and mammals ebbed and flowed, affecting the availability of resources and the presence of predators. Humans came and left, sometimes bringing food, medical care, or more dogs. Generations of animals replaced each other, and populations mingled and mixed. Olena Burdo, a radioecologist at the Kiev Institute for Nuclear Research, has worked for years to try to parse these many variables in her work with bank voles. In the wild, it’s usually easy to tell that differences between populations exist, she told me. It’s just not always possible to pinpoint why.

Without perfect record-keeping of individual canines, the team can’t prove that the modern dogs they’re sampling are directly descended from 1980s dogs, either. Burdo told me she suspects that at least some of the power-plant dogs may be more transient than the researchers think. If the three dog populations under study are loose, amorphous, and constantly turning over, the researchers will have a tough time determining the effects of higher- or lower-dose radiation exposure through generations. The power-plant dogs—the purported high-radiation cohort—may not really be a lineage born of the facility’s buildings after all.

But Ostrander is fairly convinced that the power-plant population has largely kept to itself. Life among the abandoned buildings is actually quite plush. Workers toss the dogs leftovers; tourists cheerfully sneak them snacks. And in recent years, veterinarians have banded together to provide the dogs medical care, vaccinations, and spay-and-neuter services. Beyond that, the canines may not need much. The pack seems to have grown more aloof and self-sufficient over the years, Spatola told me, and may even be behaviorally reverting to some of its wilder, wolfish roots. Left to fend for themselves when the reactor blew, this population of dogs—which started out as pets—has been transformed, perhaps by radiation, perhaps by human fallibility, into something less familiar, more strange, and entirely its own.