After the tragic explosion and the largest nuclear disaster in history at the Chernobyl nuclear power plant, many living creatures, including dogs, remained on site. Over the decades, during which animals have lived here without humans, but under conditions of higher radiation and massive contamination, they have begun to adapt to this new world. A new study, published in the journal Genes, has now described how dogs have managed this and how they have changed.
Researchers have long been interested in Chernobyl dogs. Experts have noted that they have divided into two populations in the enclosed area, with each evolving somewhat differently. The "more normal" population lives in the city of Chernobyl and is genetically quite similar to other dog populations in Russia or Belarus. In contrast, the dogs living directly in the nuclear power plant or its immediate surroundings are genetically quite different. They have managed to develop mechanisms that can repair their DNA.
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Although the two dog populations live only a short distance apart, genetically it appears as if each of them lives on an isolated island – they are so different. New research examined how these changes occurred and what their causes are. It showed that they are not caused by mutations, as initially some scientists had assumed.
The basis is that in dogs it was a case of natural selection – the process by which genes that increase an individual's adaptability to the environment in which they live become more common in the population over time. So-called directional selection is one of the ways that nature achieves this goal. The entire population of one species shifts over time toward a smaller number of favored traits. This is typically associated with changes in the environment to which species try to adapt.
The second way is known as genetic drift, which are random genetic changes that do not necessarily relate to adaptation but still become common in the population. Genetic drift is more common in small, isolated populations because the probability of passing on these random changes is higher and can lead to a reduction in diversity across the genome. These changes are common, for example, in animals living on islands and could therefore also apply to isolated Chernobyl dogs.
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To decipher this mystery, scientists examined not only the genes of animals from the contaminated area but also from regular dog populations in Eastern Europe – and also in the Galapagos, which are a typical representative of development in isolated environments.
It turned out that despite the small size of the Chernobyl population, there is currently no decrease in genetic diversity, suggesting that drift is not occurring. Genetically, the population from the nuclear power plant also differed significantly from other geographically isolated dog populations – including those from the Galapagos Islands.
A detailed analysis of Chernobyl dogs revealed that adaptation to the living conditions in the exclusion zone of the power plant manifested in at least one hundred locations in the genome. These primarily involve sites associated with cancer defense, immunity, and especially with DNA repair. According to the authors, it looks like evidence of selection: radiation and toxic substances damage DNA, and these defects can lead to malignant growth. Creatures capable of repairing these emerging errors have an advantage over those lacking this ability – and can also continue to pass these traits on.
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"While we cannot say for certain whether what we discovered can be directly confirmed as selection, we find genomic markers that suggest selection," the authors of the study stated. "When we delve deeper into these genomic areas, we find that these genes are involved in biologically relevant pathways that could enable them (the dogs) to overcome the effects of exposure to toxic substances in this environment."
In any case, it is not clear what came first. "We argue that the consequence need not have been a change in the dogs' genome for the purpose of adaptation. It is possible that those who managed to survive the initial exposure to radiation possessed just this level of basic genetic diversity and variants that provided them with a higher degree of adaptability," the authors argue in the study.
"It is clear that this is speculation, and we do not know precisely what happened. However, we can confidently say that we conducted a very thorough analysis and found signs of selection in biologically relevant areas," the scientists add.
Reference to the study (in English)
An article written by Tomáš Karlík (CT), initially published on 29 October 2026, 13:33 (CET)