Dog packs in the Chernobyl forests hold a shocking secret

Can animals survive a nuclear disaster? If so, what happens to them in the decades that follow, left alone in an environment that is dangerous and uninhabitable for humans?

A paper summarizing the results of years of research, published in March 2023 (Science Advances, Vol. 9, No. 9), reached some startling conclusions.

The previous events

On April 26, 1986, five kilometers from the Ukrainian town of Pripyat, the worst nuclear power plant accident in human history occurred when Reactor 4 at the Chernobyl power plant exploded. The 47,000 surviving residents of the town were evacuated by a convoy of over 1,200 buses spanning 2.5 kilometers. Residents were instructed to leave all pets behind, as they were told they would be able to return to their homes within a few days—a promise that, of course, was never fulfilled. A few weeks later, Soviet military shooting units were deployed in the town and surrounding areas. Soldiers were ordered to eliminate the remaining animals, including dogs and cats, that had become dangerous (sick), to prevent the spread of radiation. It was believed that none of the animals survived this tragic encounter or the ongoing radiation exposure. Until now.

The present

In the latter half of the 2010s, a team of U.S. researchers attempted to assess the genetic changes caused by the Chernobyl disaster in elk and wild boar populations within the surrounding forests. However, since only a few of these animals could be captured and studied, the true highlight of their research turned out to be mapping a population of over 800 wild dogs. These dogs live and hunt in several packs within a 30-square-kilometer radius around Pripyat and frequently visit the abandoned town. How is this possible, and what are the characteristics of these dogs?

Since access to the restricted area is nearly impossible for outside dogs, almost all individuals in this “wild dog population” are likely descendants of dogs that survived both the disaster and subsequent culling efforts. Over the past few decades, the once purebred and mixed-breed pets have lost all distinct breed characteristics. No terrier, Labrador, or German Shepherd types remain. Despite this, their appearance has become relatively uniform: the dogs are mostly medium-sized, with a herding-dog look. In this isolated dog community—free from outside influence and human control—appearance has naturally adapted for survival. There are no giant or very small dogs among them.

Although most of these four-legged creatures have never encountered humans before, they are generally wary, distrustful and fierce rather than aggressive towards humans. Younger individuals are notably friendly and often seek direct contact with the ‘disaster tourists’ who have been arriving in increasing numbers in recent years. One of the most surprising findings for researchers was the dogs’ extremely high levels of observation and memory. They could spot uniformed personnel (such as guards of the restricted area) from a distance and would immediately flee upon seeing them. Rangers assisting with genetic research experienced the same issue when attempting to capture some dogs. Even after changing their uniforms regularly, they had little success in avoiding detection

Another surprise for the researchers was that none of the 302 dogs thoroughly tested so far were found to have tumors or lesions caused by dangerous radioactive exposure. Additionally, the dogs living permanently near the damaged plant did not carry residual radiation themselves, meaning they posed no danger to other animals, according to the measurements.

The current phase of the research will involve a thorough analysis of the gene samples collected on-site. Even the preliminary test studies show a significant difference in the genetic structure between dogs living in the immediate vicinity of the Chernobyl nuclear power plant and those living and tested hundreds of kilometers away. These results may reveal whether any genetic mutations have occurred in the dogs of Pripyat that could have helped them develop immunity to harmful radiation, thereby aiding their survival.

However, the research is significantly complicated by the fact that this isolated dog community evolved and reproduced in a closed environment. Leading to inbreeding, which could also be the cause of many genetic defects. Although the researchers have not yet reached any firm conclusions, the study and genetic sampling of this unique, independently evolved pack of 800 dogs could provide an excellent foundation for understanding how prolonged exposure to radioactive radiation affects the genetics of mammals—and potentially even humans.