Microscopic worms that were suspended in a deep freeze in Siberia for 42,000 years have come back to life after being defrosted, making them the oldest living creatures on the planet and the first multicellular organisms to have survived such long-term cryobiosis.
The findings were published in the journal Doklady Biological Sciences.
Researchers from Moscow State University in Russia and Princeton University in the US analysed 300 samples of Arctic permafrost deposits and found two that held several well-preserved nematodes.
Nematodes are tiny worms that typically measure about one millimetre in length, and are known to have impressive abilities. Some are found living 1.3 kilometers below Earth’s surface, deeper than any other multicellular animal. Certain worms that live on an island in the Indian Ocean can develop one of five different mouths, depending on what type of food is available.
In this study, one sample was collected from a fossil squirrel burrow near the Alazeya River in the northeastern part of Yakutia, Russia, from deposits estimated to be about 32,000 years old, the ‘Live Science’ reported.
The other permafrost sample came from the Kolyma River in northeastern Siberia, and the age of nearby deposits was around 42,000 years old, scientists said.
The isolated worms represented two known nematode species: Panagrolaimus detritophagus and Plectus parvus.
After years of sitting in cold storage in a lab at -20° C (-4° F), the samples were defrosted in a Petri dish with an enrichment culture to promote their growth. They were warmed at 20° C (68° F) for a few weeks and sure enough, the nematodes began to move again, as well as chowing down on E. coli that had been added as a food source.
“Our data demonstrate the ability of multicellular organisms to survive long-term (tens of thousands of years) cryobiosis under the conditions of natural cryoconservation,” say the scientists in a statement. “It is obvious that this ability suggests that the Pleistocene nematodes have some adaptive mechanisms that may be of scientific and practical importance for the related fields of science, such as cryomedicine, cryobiology, and astrobiology.”
The two worms, both female, are now the oldest living things on the planet by quite a wide margin. This kind of cryobiosis has been known to work for single-celled organisms such as bacteria and amoeba, and the seeds of certain plants have been viable after years of being frozen. Earlier a group of researchers had identified a mysterious giant virus had been resurrected that was buried for 30,000 years in Siberian permafrost.
The nematodes represent the first time multicellular organisms have been able to be revived. Still, these worms are very simple creatures and, amazing as the find is, we’re not likely to be able to mimic the effects to help preserve or revive ourselves or other large animals.