The Chernobyl Nuclear Power Plant disaster of 1986 transformed a once-thriving region of Ukraine into a radioactive wasteland. Decades later, the 2,600 square kilometer Chernobyl Exclusion Zone (CEZ) is largely abandoned by humans. But wildlife remains — and adapts. Recent studies show that creatures as different as worms and free-ranging dogs thrive in Chernobyl, and it’s not exactly clear how.

Nematodes (worms) in the Chernobyl area show no sign of genetic damage, even though they’re living in highly contaminated areas.

Thriving, not surviving

In a study published in the Proceedings of the National Academy of Sciences​, researchers led by Sophia Tintori of New York University examined nematode worms collected from sites across the CEZ. The goal was to determine whether chronic radiation exposure has caused heritable mutations or was selected for greater mutagen tolerance.

“I had seen footage of the exclusion zone and was surprised by how lush and overgrown it looked — I’d never thought of it as teeming with life,” said Tintori. “If I want to find worms that are particularly tolerant to radiation exposure, this is a landscape that might have already selected for that.”

Nematodes, particularly the species Oscheius tipulae, are ideal test subjects. This is due to their small size, rapid reproduction, and adaptability to various environments. During the study, scientists gathered 298 nematodes wriggling on or beneath the soil, from areas of varying radiation levels. These locations registered radiation levels between 2 and 4,786 millisieverts per year. These levels far exceed the 1 millisievert level that humans could tolerate safely.

“These worms live everywhere, and they live quickly, so they go through dozens of generations of evolution while a typical vertebrate is still putting on its shoes,” said Matthew Rockman, a professor of biology at NYU and the study’s senior author.

These worms don’t seem to give a damn about radiation

Researchers subjected the worms to rigorous genetic analysis, including genome sequencing and tolerance tests with chemical mutagens in the lab. Surprisingly, the genomes of worms from high-radiation areas showed no more mutations than those from lower-radiation regions. Basically, there was no sign of increased mutation rates linked to radiation exposure.

The researchers also compared the genomes of these worms to the genomes of five specimens from elsewhere in the world. They were from the Philippines, Germany, the United States, Mauritius, and Australia — but they were virtually identical. Furthermore, when researchers led the worms breed, the offspring’s tolerance for radiation didn’t seem related to the radiation level endured by their parents.

In other words, it’s not like the nematodes developed special defenses against radiation, they had them to begin with. The absence of significant genomic changes doesn’t mean radiation is harmless — worms may still suffer from radiation-related damage that doesn’t manifest as heritable mutations.

“Chornobyl was a tragedy of incomprehensible scale, but we still don’t have a great grasp on the effects of the disaster on local populations,” Tintori said when the study came out. “Did the sudden environmental shift select for species, or even individuals within a species, that are naturally more resistant to ionizing radiation?”

“This doesn’t mean that Chornobyl is safe — it more likely means that nematodes are really resilient animals and can withstand extreme conditions,” noted Tintori. “We also don’t know how long each of the worms we collected was in the Zone, so we can’t be sure exactly what level of exposure each worm and its ancestors received over the past four decades.”

A dog’s tale: isolated, contaminated, inbred, yet surviving

While worms persist unseen in Chernobyl’s soil, more conspicuous survivors roam its streets and forests: free-ranging dogs. These dogs, believed to be descendants of pets left behind during the frantic evacuation of 1986, continue to breed and adapt to life in the CEZ. Two recent studies shed light on how these dogs have survived — and possibly evolved — despite constant exposure to radiation and environmental toxins​​.

Genetic analyses showed that the populations around the Chernobyl nuclear power plant and those in Chernobyl City don’t seem to interbreed, which is puzzling.

Even though these dogs occupy areas just 16 kilometers apart, a relatively small distance, dogs in the most contaminated areas tend to stick to their own group, even if this means inbreeding. It’s not clear why this is happening. It could be that they’ve developed some form of resilience to the nuclear contamination, and other groups tend to stay away from that area. It could also be that there is some human infrastructure restricting movement.

Interestingly, the dogs’ family structures resembled those of wild wolves. Multiple family groups coexisted within small areas, particularly near the power plant. Despite the harsh environment, these groups exhibited a surprising degree of social organization. They form cohesive packs of related individuals​.

The research identified 391 loci with signs of directional selection — genomic regions that may be adapting to the contaminated environment​. Among these loci, 52 candidate genes were linked to functions like DNA repair, oxidative stress response, and immune function. This is exactly what you’d expect to see in dogs trying to cope with chronic radiation exposure and other environmental toxins.

This is a suggestive finding, but it isn’t exactly a smoking gun. It’s tempting to interpret the findings as the dogs experiencing selection pressures due to environmental contaminants. But this doesn’t conclusively prove that the dogs are becoming resistant to radiation; only that they are finding ways to survive in this taxing environment.

Resilience in the ruins

The story of Chernobyl’s wildlife is a testament to the incredible resilience of life. Decades after the 1986 nuclear disaster turned a bustling region of Ukraine into a radioactive wasteland, creatures both seen and unseen continue to thrive in the exclusion zone.

For the nematodes, the surprising takeaway is that they didn’t need to evolve new defenses against radiation — they were resilient from the start. These tiny worms endure radiation levels that would devastate more complex creatures, yet their genomes show no significant damage.

For the free-ranging dogs of Chernobyl, the story is more nuanced. Their survival in the exclusion zone comes with visible challenges. Yet these dogs persist, forming complex social structures reminiscent of their wolf ancestors. They may also be adapting to radiation in their own way.

Yet perhaps the most striking finding is that even after a nuclear catastrophe, life is thriving in Chernobyl — more so than it did when humans were there. Nuclear exposure doesn’t seem to be as bad for wildlife as human activity.

In the shadow of the Chernobyl disaster, life doesn’t just merely survive. It finds ways to thrive, adapt, and evolve more than around humans. That ought to make us think.