Revision History

In 2021, Russian scientists revived a bdelloid rotifer from Siberian permafrost radiocarbon-dated to approximately 24,000 years old — the longest confirmed survival of a multicellular animal in frozen stasis at the time. The organism not only survived but reproduced asexually, raising questions about the biological limits of cryptobiosis, the potential applications for cryopreservation, and the risks posed by ancient organisms emerging from a rapidly thawing Arctic.