Russian scientists recovered a roughly 24,000‑year‑old soil core from Siberian permafrost and revived bdelloid rotifers that had been in cryptobiosis. After gentle thawing in a special medium, the microscopic animals resumed activity and asexual reproduction. The work advances cryobiology and suggests potential applications for storage, hardy crops, and extreme‑environment farming—though human applications remain speculative and far off.
24,000‑Year‑Old 'Zombie' Worms Revived: Siberian Rotifers Return From Permafrost
Scientists Revive 24,000-Year-Old ZombiesLyubov Shmakova/Handout
Russian researchers have successfully revived and cultured bdelloid rotifers—microscopic animals sometimes called "wheel animals"—that had been locked in Siberian permafrost for roughly 24,000 years. After a careful thawing process, the tiny survivors resumed normal activity, including rapid asexual reproduction.
To retrieve the ancient sample the team excavated to a depth of about 11.5 feet and extracted an intact soil core. Radiocarbon dating indicates the layer is on the order of 24,000 years old, and the region has remained frozen since at least the end of the Pleistocene epoch.
How They Survived
Bdelloid rotifers are extremophiles that can enter cryptobiosis, a reversible state of suspended metabolism. While dormant they accumulate protective compounds—such as molecular chaperone proteins—that stabilize cellular machinery and allow recovery when conditions improve.
"They suspend their metabolism and accumulate certain compounds like chaperone proteins that help them to recover from cryptobiosis when the conditions improve," said lead author Stas Malavin of the Institute of Physicochemical and Biological Problems in Soil Science, as reported by Live Science.
In the lab, researchers gently warmed the permafrost sample in a nurturing medium. The revived rotifers were soon active again—and because bdelloids reproduce asexually by producing genetically identical offspring, the team quickly lost track of which individuals were original survivors and which were newly born.
Scientific Context and Implications
These findings join a growing list of long-frozen organisms—mosses, hardy plants, and nematode worms—that scientists have revived after centuries or millennia of dormancy. Studying cryptobiosis advances cryobiology, the science of life at very low temperatures, and improves understanding of how biological systems can withstand and recover from extreme cold.
There are practical implications: discovering traits that enable long-term frozen survival could inform improvements in seed and food storage, development of hardier crops, and even concepts for farming in extreme environments such as Mars. However, Malavin and others emphasize that applying similar techniques to humans is purely speculative and extremely distant given human biological complexity.
For now, the headline is clear: life at microscopic scales can pause for geological timescales and then resume, offering a remarkable demonstration of resilience and a valuable window into the mechanisms that make such survival possible.
Reporting included comments from Stas Malavin and coverage by Live Science.
