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wolf in snow near Chernobyl
40 Years After The Chernobyl Disaster, Wolves Are Thriving. How Did They Do It?
The story is half X-Men, half The Lorax.
By Dr. Katie Spalding
Edited byLaura Simmons
In northern Ukraine and southern Belarus, there’s a region almost the size of Yosemite National Park where the population is zero. It’s not that it’s a bad place to live, exactly – until relatively recently, hundreds of thousands of people called it their home. But in 1986, something happened that forced their immediate evacuation, leaving nothing but ghost towns dotted throughout the area.
“[There are] villages that still have cars in the driveways, or they still have books on the bookshelves within the homes,” recalled Cara Love, a biologist and postdoctoral fellow at Princeton University, in a 2024 episode of NPR’s Short Wave. “There are still shoes near the front doors.”
The reason, of course, was the Chernobyl disaster: the catastrophic explosion of a reactor at the Chernobyl Nuclear Power Plant, close to the heavily populated city of Pripyat, Ukraine.
“It released over 100,000 pounds of radioactive material into the atmosphere, and that dispersed, really, all across Europe and the USSR at the time,” said Love, who now studies the health effects of living in the area around the explosion. “That whole region was evacuated by all the human inhabitants […] And that’s what we reference to as the CEZ [Chernobyl Exclusion Zone].”
But for all that the region was emptied of its human inhabitants – more or less – the area’s wild animals were harder to corral. Or rather: nobody tried. No, even that’s not quite right – it’s more like: even pets were left behind, by order of the authorities, and once their owners had gone soldiers went in and shot them.
The CE became, very quickly, a haven for wildlife and those pets that evaded capture and execution. There was just one drawback: levels of radiation so high that the animals themselves became radioactive. As Ron Chesser, now a professor of biological sciences and director of Texas Tech University’s Center for Environmental Radiation Studies, told the New York Times a full decade after the disaster, “you wouldn’t want to keep one of [the CEZ’s] voles in your pocket for any length of time.”
But… they had survived. For years, in fact. And now, 40 years post-Chernobyl, the wolves in the Exclusion Zone aren’t just thriving despite the radiation – they seem to have developed an outright resistance to it.
The sickness of Chernobyl
The first reported aftereffects of the disaster were more or less what you’d expect. Thyroid cancer in children from the area reportedly shot up to 100 times the normal rate, and reports circulated of other cancers doubling in frequency for those living in the surrounding towns and villages.
No surprise, then, that wildlife in the region was similarly afflicted. Animals were born deformed, with mutations accumulating with each successive generation: “the mutation rate in these animals is hundreds and probably thousands of times greater than normal,” observed Robert Baker, Chesser’s biologist colleague from Texas Tech, in 1996.
Now, much of what we know about wolves would suggest they would be one of the hardest hit species in the region. “Dogs within Chernobyl have higher cancer rates than dogs outside of Chernobyl,” Love pointed out; “if we extrapolate that into the wolf population, we can assume that they might have higher cancer rates.”
They’re also apex predators. Like mercury toxicity in marine life, radiation exposure builds with each step up in the food chain: the wolves are eating radioactive deer, who ate radioactive plants, which grew in radioactive soil. By the time you get to the top of the pyramid, the wolves are being exposed to an amount of radiation every day which is more than six times the legal safety limit for humans.
“Gray wolves offer a really interesting opportunity to understand the impacts of chronic, low-dose, multigenerational exposure to ionizing radiation,” said Shane Campbell-Staton, a Princeton evolutionary biologist whose focus includes the fate of the wolves in Chernobyl, to NPR. And that’s “because of the role that they play in their ecosystems.”
But here’s the thing: despite all these hindrances – their position in the food chain, their canine biology, their frankly massive exposure load – the wolf population in the Chernobyl Exclusion Zone is flourishing. There are an estimated seven times more of the animals per square meter within the CEZ than in other protected areas in Belarus – and their genomes seem to be rising to the challenges posed by constant overwhelming radiation exposure.
How the wolves live
The story of the Chernobyl wolves’ survival, it seems, is part X-Men and part The Lorax.
First, there’s the genetic story. Blood testing of the wolves revealed that sections of their genome were diverging much faster than in other populations in places further from Chernobyl. And which bits in particular are changing is important: “in general, we found that the fastest-evolving regions within Chernobyl are in and around genes that we know have some role in cancer immune response or the anti-tumor immune response in mammals,” Campbell-Stanton explained.
It’s not that the wolves are exactly immune to cancer, the pair explained – but when it does turn up, it just doesn’t do as much damage as it might in other populations: “They’re just able to take that burden better for some reason,” Campbell-Staton said. The overall effect is a kind of supercharged natural selection, where only the wolves with a higher resistance to cancer can survive the radiation long enough to reproduce.
But the other half of the story is more humbling. Frankly, it’s us – or rather, the notable absence of us.
“Humans aren’t there,” Campbell-Staton said. “A wolf within the Chernobyl Exclusion Zone – it may have to deal with pressures from cancer, but it doesn’t have to deal with pressures from, say, hunting. And it may be that the release from that hunting pressure – that separation from humans – turns out to be a much better thing than having to deal with cancer.”
It is, in his words, “kind of messed up” that humans might be more destructive to a species than theoretically mega-lethal doses of radiation. But if our absence from the area has allowed the wolves to thrive, then it’s fitting that the wolves might in turn soon help our own species to survive.
“We have started collaborating with cancer biologists and cancer companies to help us to interpret these data,” Campbell-Staton told NPR, “and then try to figure out if there are any directly translatable differences that may offer, like, novel therapeutic targets for cancer in humans, for instance.”
Written by Dr. Katie Spalding
Edited by Laura Simmons