The Evolution of Nuclear Landscapes: A Darwin Day Discussion

Natural selection has caused many dramatic changes to occur over centuries, even millennia. This evolutionary process is especially stressed in environments under challenging conditions, including in the presence of nuclear fallout. Stony Brook University’s Department of Ecology and Evolution focused on these environments — Chernobyl, Fukushima and other “hot places” — to celebrate Darwin Day on February 10.

“Charles Darwin, along with Alfred Russel Wallace, revolutionized our understanding of life by proposing the theory of evolution through natural selection, explaining how species change over time,” said John True, event co-organizer and associate professor in the Department of Ecology and Evolution. “This idea is the most fundamental principle of modern biology, and provides an organizing scaffold to our knowledge in fields from genetics to medicine to environmental science.

“Observing Darwin Day honors his contributions to science and celebrates the importance of investigating and preserving the diversity of species in nature.”

The special lecture welcomed Timothy Mousseau, ecologist and professor at the University of South Carolina, to engage with Stony Brook faculty, staff and students, as well as community members, and discuss these impacts, drawing from his research conducted in Chernobyl for the past 25 years.

Radiation has been linked to increased rates of cancer in humans since the early 20th century. Yet little was known about the environmental and evolutionary impacts until relatively recently. 

Before Mousseau began his research, some population genetic models showed that most populations in nature existed on a knife’s edge. Even a small increase in mutation rates could determine the survival or extinction of a species. Mousseau wanted to test these models using actual populations, such as insects, rodents, birds and dogs.

He described Chernobyl, an area in Eastern Europe spanning 1,000 square miles, as a unique opportunity due to the area being “a patchwork of high and low radioactivity.”

“The Chernobyl event was a ten-day event,” Mousseau said. “So, depending on which way the wind was blowing or whether it was raining, the deposition was all over the place.”

Mousseau and his team caught anything they could find, but their primary specimens were birds. Out of the 1,669 they caught, 25 had tumors or growths around their heads, beaks, feet and wings.

“This does not sound like a lot,” Mousseau said. “But, when compared to 36,000 birds that were handled in the control site, where zero cases of tumors were observed, it is highly significant. The fact that we are seeing any at all means that the actual frequency is probably much higher.”

The brain is also highly sensitive to radiation. Birds from various species in highly radioactive areas were more likely to have smaller brains, which can lead to cognitive impairments. The birds were also more likely to develop cataracts at an early age.

In addition, the Mousseau team collected sperm samples to study reproductive abilities. In highly radioactive areas, approximately 40 percent of the birds were sterile. The sperm that was collected had higher rates of deformities and abnormal swimming behavior.

All of these health complications reduce the probability of survival significantly, he said. Bird populations in highly radioactive areas were significantly lower compared to those in areas with low radiation. Diversity among individual species was also low. Similar patterns were found in the rodent and plant populations. 

The Mousseau team also repeated these experiments a few months after a major earthquake led to a nuclear disaster in Fukushima, Japan, in 2011. Despite the different environment, the results were similar to Chernobyl. The models depicting wild populations a few steps away from mutational meltdown were true. 

Nevertheless, in the two years after the Fukushima accident, the pollen viability of plants in highly radioactive activity was less than 15 percent. The pollen data from Chernobyl more than 30 years after the incident showed that viability was 70 percent. This could suggest that over the years, natural selection has led to the decline or elimination of plant genotypes more vulnerable to radioactivity, resulting in pollen that are “unbelievably tough and resistant to almost anything.”

“We have been going to Brookhaven [National Laboratory] and zapping …Chernobyl seeds with massive doses of radiation,” Mousseau said. “But a sizable portion is still viable.”

This suggests that one day, areas like Chernobyl and Fukushima may grow back stronger. In the meantime, Mousseau and other scientists hope to use genome sequencing to further investigate how natural selection may be influencing traits related to survival and reproduction in these areas.

The Darwin Day event was sponsored by the Stony Brook Collaborative for the Earth. This year’s topic of nuclear energy comes on the heels of Microsoft’s efforts to use nuclear reactors at Three Mile Island to power artificial intelligence processing. Governor Kathy Hochul also wants to explore possibly investing in advanced nuclear reactor models to reduce New York’s carbon footprint for generating electricity. 

The Collaborative will also continue the conversation of nuclear energy on February 26 with a “Science and Cinema” screening of the film Radioactive: The Women of Three Mile Island, featuring a talk-back with Heidi Hunter, director and associate professor of English and sustainability at Stony Brook.

An academic debate on the expansion of nuclear energy will also be featured during the first Climate Solutions Summit NYC hosted by The New York Climate Exchange April 23-24.

— Rachel Lea