On Friday at 4PM in the Hilton, Dr. Jessica Parilla presented “Microbes in (Semi)Permafrost,” a program on the reawakening of ancient viruses and bacteria as permafrost melts. She began by defining permafrost as soil that has been continually frozen for at least two years. The map she displayed showed large areas of purple, which denoted continuously frozen soil that was mostly in Russia, Canada, and Alaska. There are also sporadically frozen areas that occasionally melt in northern Canada, Alaska, Siberia, and northern Russia. Permafrost constitutes about 25% of the Northern Hemisphere.
As permafrost melts, Parilla said, it causes landslides and other disruptions of the local landscape. It also releases the carbon and methane frozen into it. Scientists estimate that permafrost holds twice as much carbon as the atmosphere currently does. Since carbon and methane are greenhouse gases, they contribute to atmospheric warming, which, in turn, contributes to increased melting, and so on. Rising temperatures over the next century will melt a lot of permafrost and sea ice.
The top area of permafrost is the active layer. Layers deeper into the soil strata may not melt, and those deep layers are perfect freezers with ideal conditions for preserving for animal corpses, including those of extinct animals, as well as humans and their ancestors like Neanderthals and frozen plant matter. As the permafrost melts, it releases its contents, which sometimes flow into water systems.
In Russia, melting permafrost revealed a desiccated corpse of a woolly mammoth that was 45,000 years old. Its organs were “almost pristine,” and the stomach still held its last meal. The discovery also allowed scientists to see bacteria and plant matter from the era when the mammoth lived.
Melting permafrost has also yielded a bone from a 700,000-year-old creature that was an ancestor of the horse and possibly of giraffes. The bone was so well preserved that the genome was intact. This is now the oldest fully sequenced genome.
Parilla pointed out that epidemics in the past often led to victims being buried in mass graves. Because civilization arose by rivers and lakes, these graves were often not especially far from the water. With permafrost melting, the rivers overflow, eroding what’s around them and possibly cutting into mass graves that may have contain bodies carrying diseases such as smallpox. The graves could also contain the bodies of people who died of diseases that are unknown today. If there are pre-human corpses affected, what kinds of viruses and diseases would be preserved in them?
Frozen plant matter, she said, is also cause for concern. Areas that are now frozen may have had abundant vegetation in the past. The diseases frozen in ancient plants could devastate modern crops.
When asked how long microbes could last in permafrost, Parilla replied that it depended on several variables. Temperature, pH levels, and salt levels would need to be constant. Cycles of freezing and thawing damage organic matter. She also pointed out that bacteria are hardier than viruses because bacteria don’t require hosts. An ice core from Alaskan permafrost contained bacteria that were 32,000 years old. After gentle thawing in the lab, they started swimming and reproducing as thought they’d never been frozen. An ice core from Antarctica yielded bacteria that were eight million years old. When thawed, they also behaved as though they had never been frozen.
Parilla also noted that the giant crystals in Mexico’s crystal caves have bacteria that’s 10,000 to 50,000 years old trapped in them. One bacterium was four million years old and already resistant to 18 antibiotics. If it caused a disease outbreak, there might be no way to control it. She pointed out that antibiotics come from funguses and bacteria and said there may be a chance to discover antibiotics that are also unknown and use them to control such outbreaks.
In contrast to bacteria, viruses can’t survive long without a host. Parilla described them as “more fragile” than bacteria. If an ancient virus were to be awakened, it would have a very short window of opportunity to pick up a new host before it died. Acorns found in squirrel nests frozen for 30,000 years have been planted and produced oak trees, but there are no viruses of equivalent age.
A virus discovered in Siberia, however, was unusual in its size and shape and broke all the rules for viruses. It belongs to a comparatively new category, giruses. It also has an odd mix of genes, with the functions of about 30 percent of them remaining a mystery.
The virus that caused the 1918 influenza pandemic, the deadliest in history with 50 to 100 million cases worldwide, is extinct. Researchers have been looking for active samples in corpses so they can develop a treatment if it ever emerges again.
When asked what the impact would be if some unknown virus were exposed and started spreading, Parilla said she thought measures such as geographic isolation and quarantine would help. She added that a bigger problem would be hysteria.
The odds of newly exposed bacteria getting into the water supply are high, especially for varieties that form spores and are thus highly resistant to environmental pressures.
An audience member asked about the health issues that would arise when people didn’t realize they were infected, as has often happened with the flu. Parilla discussed the spread of Ebola via an infected patient and the difficulties of treating him when so little was known about the virus and the protective gear that would block it. Access to world databases, she said, was important in treating all such outbreaks.
Discussing the possible whether a disease could ever truly be eradicated, Parilla said that was uncertain. The last smallpox epidemic occurred in 1979, so now people are not being vaccinated for the disease and would be vulnerable if it reemerged. Rinderpest, which strikes both domestic and wild animals, has also supposedly been eliminated, but it’s impossible to be sure.
Parilla observed that planning for particular doomsday scenarios was pointless because that particular problem might never occur. It’s better to plan general emergency response that can be extrapolated for any problem. She also noted that the ancient enzymes and biochemicals could possible produce benefits and that we have a lot to learn in this field.