These tiny animals spent 24,000 years frozen in Siberia, then started cloning themselves

Woolly mammoths were still around when this animal went into the deep freeze. About 24,000 years later, it thawed out and started making copies of itself.

A core sample from Siberia

The creature is a bdelloid rotifer from the genus Adineta: a microscopic multicellular animal that usually lives in freshwater or moist soil. Researchers drilled permafrost cores 11.5 feet (about 3.5 meters) deep near the Alazeya River in Siberia. Radiocarbon dating of the surrounding soil put the find at about 24,000 years old.

Bringing it back sounds almost too simple. According to Smithsonian Magazine, co-author Stas Malavin from the Soil Cryology Laboratory in Russia explained it like this: put a piece of permafrost in a Petri dish with a suitable medium, then wait for dormant organisms to recover, start moving and multiply. “We revived animals that saw woolly mammoths, which is quite impressive,” he said.

Cloning itself into the present

Once thawed, the rotifer reproduced through parthenogenesis, a clonal process that needs no partner, reports the U.S. National Science Foundation, which funded the work. The study appeared in the journal Current Biology in 2021.

Before this, frozen rotifers had a much shorter track record: earlier reports had them surviving 6 to 10 years at temperatures between minus 20 and 0 degrees Celsius. In the lab, the team froze and thawed dozens of rotifers and found that they could withstand the formation of ice crystals during slow freezing. The researchers suspect some mechanism that shields their cells and organs at very low temperatures.

Bonus fact: Rotifers aren’t the only ones with an ice age comeback. Smithsonian Magazine reports that a nematode worm was previously revived after an estimated 32,000 to 42,000 years frozen in Siberia.

Malavin called the find “the hardest proof as of today” that these animals can survive tens of thousands of years in a dormant state. He also admits it’s not yet clear what it takes to survive on ice for even a few years. Big mystery, tiny animal.