What We Know About The Animals Evolving At Chernobyl

Chernobyl is a name synonymous with catastrophe. On April 26, 1986, a reactor at the Chernobyl Power Complex, a boiling water nuclear power plant located in northern Ukraine, exploded during a maintenance test, blanketing its surroundings in a cloud of radioactive material. The consequences were devastating. Two people died in the explosion, and within three months, another 28 had died, mostly from acute radiation sickness. To spare future lives, the ruined reactor was encased in concrete, the nearby town of Pripyat was evacuated, and all the land within nearly 20 miles of the plant was declared off limits.

Today, the Chernobyl Exclusion Zone (CEZ) remains one of the most radioactive sites on the planet. Over 100 different radioactive elements were released by the meltdown, and while most decayed swiftly, some of the most dangerous, like the carcinogenic cesium-137, remain in high concentrations. You would expect this area to be a completely barren wasteland, inhospitable to any life, but that is far from the truth.

The Chernobyl disaster forced humans out of the area, and our exit has offered new freedom to wildlife. The CEZ has inadvertently become mainland Europe's third-largest nature reserve. It hosts insects, amphibians, fish, mammals, and more than 200 different species of birds. Their population numbers are strong, but radiation poses dangers to all animals, and scientists have found some weird things around the old power plant. This has launched an international debate as to whether or not the Chernobyl disaster is changing the course of evolution.

The most famous of Darwin's main ideas on evolution is the concept of survival of the fittest. Individuals with beneficial genetic mutations are more likely to survive and progress their species. What does it take to survive a radiation-ridden region like the CEZ? A group of tree frogs offers one answer. A 2022 study examined Eastern tree frogs from inside and outside the CEZ, and found that the frogs had increasingly high levels of melanin the closer they lived to the plant. Darker skin is better at protecting against radiation, so it makes sense that in the immediate aftermath of the meltdown, frogs with low melanin levels perished while those with high melanin levels lived to reproduce.

Perhaps the most famous animals in the CEZ are the wild dogs. When Pripyat was evacuated, its residents were only permitted to take things they could carry, forced to leave their pets behind. Three decades later, the descendants of these abandoned dogs appear to have unique genetics. Two studies from 2023, one published in Science Advances and the other in Canine Medicine and Genetics, found that dogs in the CEZ were genetically distinct from those outside the zone. Furthermore, dog populations within the zone varied genetically based on radiation exposure. Unfortunately, some of these genetic differences pose challenges for the dogs, including a notably high rate of cataracts. The long-term results of these effects are still unfolding, and more species will need to be studied to reveal the true legacy of Chernobyl.