Old life wakes up in the midst of the thaw of ice caps and permafrost

From about 1550 to 1850, a global cold wave called the small glaciers of the Ice Age in the Arctic. On Ellesmere Island in Canada, the Teardrop Glacier extended its frozen tongue across the landscape and swallowed a small tuft of moss.

Since 1850, the plant was frozen under a 100-foot thick ice sheet when humans discovered antibiotics, visited the moon and burned two trillion tons of fossil fuels.

Thanks to this last exploit, the evolutionary biologist Catherine La Farge arrived centuries later on the edge of the melting of Teardrop to find the bunch of the species Aulacomnium turgidum finally released from its frozen landfill. The moss was faded and torn, but had a green hue – a possible sign of life.

Climate change stories often highlight the flickering fragility of Earth's ecological system. The situation has become even more critical when a UN report said that one million species of plants and animals on our planet are threatened with extinction. But for some exceptional species, the thaw of the ice sheets and permafrost is beginning to reveal another story, that of an astonishing biological resilience.

Researchers in a warming Arctic are discovering organisms, frozen and presumed dead for thousands of years, capable of reviving life. These ice age zombies range from simple bacteria to multicellular animals and their endurance encourages scientists to rethink their understanding of what it means to survive.

"You would not think that everything that would be buried for hundreds of years would be viable," said La Farge, who is doing foam research at the University of Alberta. In 2009, his team was exploring the Teardrop margin to collect plant material blackened by shrinking glaciers. Their goal was to document the vegetation that once formed the base of the island's ecosystem.

"The material had always been considered dead. But seeing the green fabric: "I thought: it's rather unusual," La Farge said about the tufts of moss that she has found for centuries.

She brought back dozens of these curious samples to Edmonton, lavishing them with nutrient-rich soil in a warm, bright laboratory. Nearly a third of the samples exploded with new shoots and leaves. "We were pretty blown away," La Farge said. The moss has shown little adverse effects from its multi-year freezer.

It is not easy to survive being frozen. Shredded ice crystals can shred cell membranes and other vital biological machines. At the beginning of winter, many plants and animals simply succumb to the cold, wanting their seeds or eggs to spawn a new generation in the spring.

Mosses have traced a more difficult path. They dry out when the temperature drops, thus avoiding the risk of ice formation in their tissues. And if some parts of the plant are damaged, some cells can divide and differentiate into different types of tissues that make up a complete foam, similar to stem cells from human embryos.

With these adaptations, mosses are more likely than other plants to survive long-term frost, said Peter Convey, an ecologist with the British Antarctic Survey.

After the rebirth of the Canadian moss at La Farge, the Convey team announced that it had awakened a 1,500-year-old moss, buried more than three feet underground in the Antarctic permafrost.

"The permafrost environment is very stable," said Convey, noting that the permanently frozen ground could isolate the foam from surface aggressions, such as annual freeze-thaw cycles or radiation that is harmful to the environment. DNA.

The regrowth of age-old mosses suggests that glaciers and permafrost are not just cemeteries for multicellular life, they could instead help organisms resist glacial periods. And while man-made warming is pushing the pack ice away from the Arctic and Antarctic, the one that brings it out alive is about to dominate the emerging polar ecosystems.

Convey explained that when ice melts exposed surfaces, plants usually colonize the new land "elsewhere" via spores transported long distances by the wind. Such dispersion is slow and often takes decades. But "when something can survive in situ," Convey said, he discovered "the process of recolonization is really accelerated." These mosses can paint a lifeless green landscape almost overnight, paving the way for other organisms.

These insects survive just about everything

Although the older mosses discovered by La Farge and Convey are remarkable, the Ice Age survivor clique extends far beyond this group of plants.

Tatiana Vishnivetskaya has studied ancient microbes long enough to make routine extreme sensations. Microbiologist at the University of Tennessee, Vishnivetskaya has explored Siberian permafrost to map the network of unicellular organisms that flourished long ago. She has managed to bring back to life bacteria of a million years in a petri dish. They look like "a lot of the bacteria that can be found in cold environments (today)," she said.

But last year, the Vishnivetskaya team announced an "accidental discovery" – an attack of the brain and nervous system – that upset scientists' understanding of extreme endurance.

As usual, researchers were looking for unicellular organisms, the only life forms considered viable after millennia locked in permafrost. They placed the frozen product on petri dishes in their room temperature lab and noticed something odd. Among the stubborn bacteria and amoebae, there were long segmented worms with a head at one end and an anus at the other – nematodes.

"Of course, we were surprised and very enthusiastic," said Vishnivetskaya. The nematodes that came back to life were some of the most complex creatures that Vishnivetskaya – or whoever else – had recovered after a long frost.

She estimated that a nematode was 41,000 years old – by far the oldest living animal ever discovered. This worm, which lived in the soil under Neanderthalian feet, had lived in the high-tech laboratory of Vishnivetskaya to meet modern humans.

Experts have suggested that nematodes are well equipped to withstand millennia trapped in permafrost. "These machines survive just about everything," said Gaetan Borgonie, a nematode researcher at Extreme Life Isyensya in Gentbrugge, Belgium, who did not participate in the Vishnivetskaya study. He added that nematodes are ubiquitous in the various habitats of the Earth. Borgonia has found many nematode communities two miles from the Earth's surface in mine pits in South Africa, with very little oxygen and scorching heat.

When environmental conditions deteriorate, some species of nematodes can sink into a state of suspended animation called the stage dauer – dauer means duration – in German – in which they prevent food and develop a protective coating that will protects from extreme conditions.

Vishnivetskaya does not know if the nematodes that his team has removed from the permafrost have passed the eras at the dauer stage. But she assumed that nematodes could theoretically survive indefinitely if they were stably frozen. "They can last for years if their cells remain intact," she said.

Borgonie agrees. He acknowledged that the discovery of Pleistocene nematodes was "a huge surprise," he said. "If they survive for 41,000 years, I have no idea what is the upper limit."

He envisions the virtuoso endurance of nematodes in a cosmic context. "This is very good news for the solar system," said Borgonie, who believes that these feats of survival could foreshadow life on other planets.

Here on Earth, many species are on the verge of extinction as humans disrupt the global climate. But near the thaw poles, some robust organisms reveal incredible endurance. It's an ecological gospel that some creatures – from birds to butterflies to wildebeest – survive by migrating vast dangerous distances to find a favorable habitat. More recent discoveries suggest another mode of migration: over time.

After prolonged sleep in the icy fringes of the Earth, bacteria, mosses and nematodes wake up in a new geological epoch. And for these endurance models, the weather is auspicious.