Ancient pathogens that escape from thawing permafrost have the potential to survive in modern microbial communities, sometimes killing off their diversity and becoming the dominant strain. Further down the line, the impact of this is unforeseeable – and it’s this unpredictability that scientists are most worried about.
To reach these findings, scientists used intensely detailed computational simulations that involve a digital virus-like pathogen from the past being introduced into a digital Petri dish with other bacteria-like hosts. They then click “go” and see what unfolds.
“We use artificial life simulations. You have these digital organisms, which are like computer programs that compete for resources. Although they’re quite abstract, they act like bacteria. They use resources to grow, they compete, they reproduce, and they interact with the environment in a similar way,” Giovanni Strona, lead study author from the European Commission Joint Research Centre and the University of Helsinki, told IFLScience.
Along with having the benefit of not handling real germs, the simulations allow the researchers to repeat the simulations time and time again while finely tweaking the many different variables.
The simulations found that ancient invading pathogens could often survive and evolve in the modern microbial community, which itself is a striking discovery. Furthermore, the ancient bacteria were very successful. In around three percent of cases, the ancient pathogen outcompeted the modern-day bacteria and became the dominant species.
In other cases, the ancient pathogen ended up actually increasing the microbial diversity. In one percent of cases, the invaders yielded unpredictable results, which was the most worrying of all.
“An invader with the ‘proper’ characteristics might fail, while some invaders that seemed unlikely to succeed could actually be very successful and be very nasty to the community,” Strona explained.
“It’s the sheer unpredictability of the process which is bad news because it tells us that it's very hard to be prepared,” he added.
With global temperatures continuing to rise and rise, it’s a very real possibility that dormant microbes that have been frozen in ice caps and permafrost for thousands of years could be reawakened and released into the environment.
While the big concern is whether these ancient pathogens could infect humans and spark a new pandemic, the new research highlights a much subtler – but not necessarily less damaging – threat.
By reintroducing microbes back into long-standing environments, it's meddling with the precious equilibrium that’s perhaps been stable for thousands of years. Like a butterfly effect, the reintroduction of a tiny microorganism could have profound effects on the wider ecosystem.
“Messing with the structure of ecological communities is not a good thing, even if the net diversity remained the same or even if you have an increase in diversity,” continued Strona.
“We might have sort of cascading effects, which are totally unpredictable. You can trigger cascading effects which might collapse ecosystems or bring more extinctions,” he said.
This, too, could directly impact humans. Like all living things, we are inseparably intertwined with the trillions of microorganisms that live in and around us. By adding new unwanted characters into the mix, long-standing balances could be tipped, raising the risk of disease and disaster.
“Regarding human health, we might end up messing up situations that have been stable for a long time,” he added.
The study is published in the journal PLOS Computational Biology.