Scientists Revive Tiny Animals That Spent 24,000 Years on Ice

These bdelloid rotifers survived for thousands of years in the Siberian permafrost and scientists want to find out how

A rotifer seen under a microscope
A rotifer seen under a microscope. Michael Plewka

Scientists were able to revive a tiny, multicellular animal called a bdelloid rotifer that had been frozen in the Siberian permafrost for 24,000 years, reports Marion Renault for the New York Times. The wiggling, microscopic critter was even able to reproduce, despite having spent tens of thousands of years in a deep freeze of around 14 degrees Fahrenheit.

Rotifers look a bit like translucent worms and tend to inhabit freshwater or moist soils. Like tardigrades or water bears, rotifers are renowned for their toughness in the face of radiation, extreme cold, dehydration and low oxygen levels, reports George Dvorsky for Gizmodo. But this new study, published this week in the journal Current Biology, sets the bar even higher.

"Our report is the hardest proof as of today that multicellular animals could withstand tens of thousands of years in cryptobiosis, the state of almost completely arrested metabolism," says Stas Malavin, a researcher at Russia’s Soil Cryology Laboratory at the Institute of Physicochemical and Biological Problems in Soil Science and co-author of the research, in a statement.

“We revived animals that saw woolly mammoths, which is quite impressive,” Malavin tells the Times.

The team found the organism in permafrost cores drilled 11.5 feet deep near the Alazeya River in Siberia. Researchers confirmed the rotifer’s advanced age by radiocarbon dating the surrounding soil.

However, while 24,000 years is an awfully long time, this rotifer isn’t the oldest organism to be brought back to life after millennia on ice. Prior research documented the resuscitation of another microscopic creature called a nematode worm thought to have spent between 32,000 and 42,000 years frozen in Siberia, reports Mindy Weisberger for Live Science.

To bring the rotifers back to life Malavin tells Live Science that he and his co-authors would “put a piece of permafrost into a Petri dish filled with [a] suitable medium and wait until organisms that are alive recover from their dormancy, start moving, and multiply."

By exploring the unique ability of certain microorganisms to seemingly put all their bodily functions on pause for thousands of years, researchers may be able gain insights into how something similar could be accomplished with more complex lifeforms like us.

"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," says Malavin in the statement. "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."

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