24,000-year-old microorganisms thawed from Siberian permafrost

Remarkably, the tiny creatures aren't even the oldest beings to be successfully returned to life after spending millennia in the deep freeze.

Life finds a way, as the saying goes – even after spending millennia trapped beneath the frozen soil.

Researchers in Russia announced that they successfully thawed out a certain kind of microorganism that had lain dormant 3.5 metres below the Siberian permafrost for some 24,000 years. In that time frame, humanity's sparse ancestors hadn't yet spread to cover the whole planet, and were thousands of years away from mastering the plow or domesticating animals.

Known as rotifers, the creatures, too small to be seen with the naked eye, not only appeared healthy, they were also able to reproduce.

Rotifers had already been known to survive freezing for up to 10 years, and the experiments, whose results were published last week in the journal Current Biology, also showed the organisms could withstand seven days of slow freezing.

Rotifer side view Michael Plewka

Lateral view of a rotifer (Michael Plewka).

"The takeaway is that a multicellular organism can be frozen and stored as such for thousands of years and then return back to life--a dream of many fiction writers," Stas Malavin of the Soil Cryology Laboratory at Russia's Institute of Physicochemical and Biological Problems in Soil Science, said in a release.

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It's not the first time impossibly ancient life forms have been thawed out in this manner, and these rotifers aren't even the oldest. In previous years, single-celled organisms have been successfully revived, and in 2018, nematodes were successfully resurrected from a permafrost slumber that had lasted at least 32,000 years.

"Of course, the more complex the organism, the trickier it is to preserve it alive frozen and, for mammals, it's not currently possible. Yet, moving from a single-celled organism to an organism with a gut and brain, though microscopic, is a big step forward," Malavin said of the latest research.