The Chernobyl accident on the 26th of April 1986, the mixture of molten fuel bears the nickname “Elephant’s Foot” which hides the gruesome reality behind the reactor that stole the lives of 350,000 forced evacuees. At 01:24 am on the 26th of April RBMK Reactor 4’s core had a meltdown caused by a failed safety test conducted by criminally inexperienced night staff. 36 hours later, a 30km Chernobyl Exclusion Zone (CEZ) was identified and publicly announced. The accident is a minefield for anthropocene evolution.

Following the explosion of the core, a purge of all livestock and animals within a 15km radius was initiated by the Ukrainian Ministry of Internal Affairs to prevent the spread of radioactive contamination. While 618 tons of radioactive meat from cows was churned with clean meat in sausages, the fate of dogs were left undetermined as animals fell far below the government’s priority list. It is believed that around 900 stray dogs are still present in Chernobyl, with common breeds including household favourites- Rottweiler and Labrador retriever. This study aims to dwell into the possibility of hyper evolution occurring over a mere 40 years.

While there have been several studies into the effect of acute radiation syndrome (ARS) in humans, there have been no long-term studies into the canine species. The study into dogs could hint at future vaccines and project the return of civilians back to Pripyat, Ukraine.

A Crash Course on the Chernobyl incident

The feebly-created test plan required a gradual decrease in reactor power to 700–1000 MW. However, due to the reactor's production of a fission byproduct, Xenon-135, absorbed neutrons and held back the rate of reaction, power continued to plummet below safe operating levels.

Xenon-135 is nuclear fission's own poison pill; as uranium atoms split, they create this xenon isotope. To raise the power, they hastily removed nearly all 211 control rods, and the power surged to 33,000 MW leading to the worst recorded nuclear accident in history.

Plumes of smoke-up to 1km-dotted the sky with two radionuclides, Iodine-131 and Caesium-137, were released during the core explosion (both were products from the fission of Uranium-235).

The immediate aftermath of the explosion triggered a desperate race against time to contain the radioactive inferno. Over approximately 5,000 tonnes of materials—including about 40 tonnes of Boron compounds were dropped onto the burning reactor core by military helicopters to minimize the release of radioactive particles.

The paradox of wildlife? Researchers believe the population increased following the absence of humans, however there are no records prior to the explosion to solidify this claim.

"Most people think of the Chornobyl nuclear accident as a radiological disaster in an abandoned corner of Ukraine, but the potential adverse health implications are much wider," says Norman Kleiman, co-author and professor of environmental health sciences at the Columbia University School of Public Health.

Daunting discoveries combat unanswered variables

The feared, yet iconic, trio in biology: mutation, selection and genetic drift has caused significant changes in the genome of dogs in Chernobyl over the years. The University of South Carolina and the National Human Genome Research Institute examined the DNA of 302 feral dogs found within 45 km of Nuclear Reactor 4. This falls into the CEZ which has radioactivity levels is up to 400 times higher than the global average. The study can be broken down into physical measurements, health indicators and development abnormalities. The objective of the study was to compare allele frequencies to nearby dogs in Russia, Ukraine and Belarus.

Blatant signs of disintegrating health

These feral and domestic canines have been exposed to continuous low-level radiation -it is currently between 6 and 12 micro-Roentgens per hour in comparison to the international average of 0.1roentgens per year. Countless dogs were victims to elevated count rates (high number of radioactive decays per unit time), believed to be from Sr-90 to the extent that washing or shaving did not reduce the count rate. They suffered increased rates of cataracts, twinning with the first symptoms of ACR in humans as eyes are the first tissues to show signs of chronic exposure. A total of 33 dogs had Cs-137 above 1 kBq/kg, yet this is not enough to pose an ionizing risk to external individuals (Cs-137 is primarily a Beta emitter and Beta can only travel around 30 cm in air and is stopped by skin tissue).

The irradiated dogs adapted to chronic exposure through natural selection (where an environment favours a particular gene expressed by Charles Darwin’s theory) where cancer suppressing genes were favoured. A study in 2018 displayed the chromosomal aberration (changes within the structure or number of chromosomes in a cell) and fertility rate, but this was believed to not have any correlation with the radiation present.

The Canine Medicine and Genetics study, propelled to success by environmental health scientist Dr. Norman J. Kleiman from Columbia University, identified 52 genes associated with these outlier loci (dogs found in the CEZ) that ‘could be associated with exposure to the contamination of the environment at the nuclear power plant,’.

A break in expectations

While they expected to find statistics to prove the presence of heavy metal poisoning or potential pigmentation changes driven by increased melanin, it ended up being a cold lead. The study was made on the assumption that mutations caused by inbreeding are negligible and bore sample size constraints. Physical safety enforcements to contain radioactivity within the CEZ is the prime reason for higher rates of inbred dogs due to reproductive isolation.

They found no evidence of drastic mutations, that can be tied back to the radiation exposure, however the tested dogs are believed to be 30 generation descendants from the dogs present during the explosion and may have already gained the fruits from selection pressure (an external factor that causes certain genes to become more favourable in an environment).

Despite the dire results, the study created a pedestal for prospects; Clean Futures Fund was able to neuter over 350 dogs, curating a safer path for future medical assessments. Chernobyl dogs may become the blueprint for survival in the nuclear age!