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After 42,000 years for one and 30,000 years for the other, they are still alive. However, it is unlikely that they will be able to come and tell us what life was like when it was the good time, the time before, the time before we got too hot, since these are worms. More precisely, two species belonging to the nematode group. It was a team of Russian researchers, accompanied by an American, who published this amazing discovery in the journal of the Russian Academy of Sciences Doklady Biological Sciences.
Russian biologists have extracted two samples from Siberian permafrost containing hundreds of nematodes (roundworms) aged 42,000 years in one case and 30,000 years in the other (late Pleistocene). Permafrost is by definition a soil whose temperature never rises above 0°C. It covers 20% of the Earth’s surface.
“When you deal with nematodes, you can expect anything,” says Jean-Lou Justine, a professor at the National Museum of Natural History. “These are very cold resistant worms. That they have waited nearly 42,000 years is certainly surprising, but quite credible.” In 1946, scientists had succeeded in bringing nematodes back to life in 39-year-old plant samples. Lateigrades, a closely related species, also withstood a 30-year stay in ice at -30°C. But never before had scientists witnessed such a long sleep.
Nematodes do not dig as deep
The first worms belong to the genus Panagrolaimus, they were discovered at a depth of 30 meters, in a layer dated 30,000 years. The latter are representatives of the genus Plectus. They were dug up at 3.5 metres in a layer that dates back almost 42,000 years. “In both cases, they are very small worms (a few tenths of a millimetre, editor’s note),” says Jean-Lou Justine. “This only increases their ability to resist.”
When brought back to Moscow, only two of these worms still showed signs of life. They were heated for several weeks in a Petri dish at 20°C with agar-agar (an algae) and E. coli bacteria as food. The worms then gradually woke up. Although contamination cannot be completely ruled out, the researchers claim to have followed a very strict sterilization procedure. It is also excluded that other worms may have subsequently entered the soil. Such worms are not known to dig so deep, especially since permafrost does not thaw over 80 cm. And over the last 40,000 years, there is no evidence that even in their hottest hours, these Siberian soils have not thawed over more than 1.50 metres.
A sleeping danger?
Is such an achievement possible for other species? For Russian researchers, the adaptation mechanisms of these small worms can be used in other related scientific fields, such as cryomedicine, cryobiology and astrobiology. A better understanding of the biochemical mechanisms used by nematodes could pave the way for better cryopreservation technologies. An idea that convinces Jean-Lou Justine much less. “Nematodes have a structure so different from ours that it seems impossible to me at the moment to transpose these extraordinary resistance capacities to much more complex organisms!”
But behind this discovery, there may be much more worrying news behind it. If the nematodes have managed to survive for so long, Russian researchers are concerned about microbes that could also have been trapped in the ice. Bacteria and viruses that could be awakened by global warming. However, no one knows what the consequences would be for living organisms.
Translated with www.DeepL.com/Translator
