A worm frozen in Siberian permafrost for 46,000 years — since woolly mammoths still roamed — was thawed in a lab dish and simply woke up, began eating, and started reproducing, because its species can shut its metabolism down to a complete standstill in a survival state biologists call cryptobiosis | Brendan Brown, ScienceBlog
Forty metres below the surface of the Siberian Arctic, in the frozen wall of a riverbank called Duvanny Yar, scientists dug out a fossilized burrow. An arctic ground squirrel had packed it with grass and seeds sometime in the depths of the last Ice Age, back when woolly mammoths and cave lions still walked the Kolyma lowlands, and then the whole thing had frozen solid and stayed that way.
Inside the ancient nest material, alongside the dead grass, were microscopic roundworms. Researchers placed some of the thawed soil in a dish of nutrient solution, kept it warm, and waited.
The worms woke up.
Just add water
They did not merely twitch. Within days the tiny nematodes, each about a millimetre long, were wriggling, feeding on bacteria in the dish and laying eggs. One of the study’s authors, evolutionary biologist Philipp Schiffer of the University of Cologne, put it plainly: they are alive because they move, they eat, and they reproduce. Life had simply resumed, as if the intervening dozens of millennia were a pause between two heartbeats.
The soil around the worms was the key to their age. Radiocarbon dating of the plant material in the burrow put it at roughly 46,000 years old, and because permafrost at that depth never thawed in between, the worms could not have wandered in later. They had been locked in since the late Pleistocene. Anatomically modern humans were still sharing the planet with Neanderthals when these animals last ate a meal.
A new species from a lost world
The revived worms turned out to be something science had never seen. Genome sequencing and analysis, published in PLOS Genetics, showed they belonged to an undescribed species, which the team named Panagrolaimus kolymaensis after the Kolyma River.
The species has a convenient trick for rebuilding a population from nothing: it is all-female and reproduces by parthenogenesis, cloning itself without any need for a mate. A single thawed survivor can found a dynasty, and in the lab that is exactly what happened. The original Ice Age individuals have since died of ordinary old age, a nematode’s natural lifespan being a matter of weeks, but their descendants have been cultured for more than 100 generations and are still going. Somewhere in a laboratory today, worms are eating bacteria whose great-many-times-grandmother hatched before the invention of agriculture, writing, or the wheel.
The pause button
The trick behind the survival is called cryptobiosis, and it is one of the strangest capabilities in biology. An organism entering cryptobiosis is not hibernating or sleeping. It shuts down entirely. Metabolism drops to levels no instrument can detect, oxygen use stops, and by every practical measure the animal is dead. Except that it is not, because the state is reversible. Add water and warmth, and the machinery restarts.
Tardigrades, the famous microscopic “water bears,” use the same trick, and it is why they can survive being dried out, frozen, and even exposed to the vacuum of space. The Siberian worms showed how it works at the molecular level. When the researchers compared P. kolymaensis with C. elegans, the lab workhorse of nematode science, they found the two species share much of the same genetic toolkit. Both, when preparing to shut down, flood their cells with a sugar called trehalose, which protects membranes and proteins from the damage of freezing and drying, essentially vitrifying the cell’s contents so nothing tears when the water leaves.
The mildly dried worms in the study survived being frozen at minus 80 degrees Celsius and came back fine. Prepared correctly, the pause button seems to hold almost indefinitely.
The record, and the fine print
Before this, the credible record for revived nematodes stood in the centuries-to-millennia range, and the same Siberian team’s earlier claim of 42,000-year-old worms had been met with scepticism about contamination. The new work answered much of it: precise dating, a sealed frozen context, and a full genome showing a distinct species rather than a modern stray.
Some caution survives, as it should. A few researchers note that the freezing experiments in the lab, where worms were dried first and then frozen abruptly, do not perfectly mimic conditions in wet Arctic soil, so exactly how the original animals entered their long pause remains partly open. But the central fact, that complex multicellular animals sat lifeless in the ice for 46 millennia and then resumed living, is now about as well-documented as such a claim can be. One biologist not involved in the work called it, accurately, mind-boggling.
What 46,000 years of sleep means
The find rewrites an assumption about time and life. For these worms, 46,000 years was not a lifetime; it was a skipped chapter. A species can apparently step out of existence during a bad epoch and step back in when conditions improve, which means the permafrost is not just frozen dirt. It is a seed bank of paused animals, some of which are waking now as the Arctic thaws.
For humans, the interest is practical. Understanding how trehalose and its supporting genes preserve cells through a total shutdown could improve how we store transplant organs, blood, vaccines and other living tissue. The worm that woke up after 46,000 years is a proof of principle written by evolution: life, correctly prepared, can wait almost forever.
A worm frozen in Siberian permafrost for 46,000 years — since woolly mammoths still roamed — was thawed in a lab dish and simply woke up, began eating, and started reproducing, because its species can shut its metabolism down to a complete standstill in a survival state… pic.twitter.com/e9l5wtVeGd
— Owen Gregorian (@OwenGregorian) August 25, 2026
Factcheck: This is legit science, not some random claim.
Scientists really did thaw out nematodes from Siberian permafrost that had been frozen for about 46,000 years.
They woke up, started eating bacteria, and made babies by cloning themselves.
The paper came out in 2023 in PLOS Genetics. Major outlets covered it.
Some scientists still side-eye the exact dating method, but the core revival is solid.