46,000-year-old worms wriggle back to life after scientists defrost them
Stone Age worms dug up from the Siberian permafrost were brought back to life after 46,000 years in suspended animation - becoming the oldest-known creatures to have existed.
The roundworms were discovered by Russian scientists inside a fossilised squirrel burrow and a deep glacial deposit near the Kolyma River in 2018, but it was unclear what they were, or how long they had been trapped in the ice.
Now genetic sequencing has shown they are an entirely new species of nematode worm which has lain dormant since the last Ice Age.
Radiocarbon dating of plant material found on the same level of the worms has shown that the frozen deposits had not thawed since the late Pleistocene.
It means they existed when Neanderthals, woolly mammoths and saber-toothed tigers still roamed the region.
The tiny worms, which are less than a millimetre in length, were thawed out and coaxed back to life in a petri dish filled with a nutritious soup designed to encourage their growth. After a few weeks in the dish, they began moving and eating.
The worms died within a few months, however scientists said the species has reproduced and is now undergoing lab experiments.
Dr Phillip Schiffer, group leader of the worm lab at the University of Cologne, told The Telegraph: “Usually Panagrolaimus nematodes live 20-60 days.
“They instantly started reproducing and we do have a culture of these worms in the laboratory. Thus, the species is alive and we are doing experiments on it.”
Nematode worms are one of several creatures known to be able to survive harsh conditions by entering a hibernation-like state called cryptobiosis. In 2021, Bdelloid rotifers, a class of microscopic invertebrates, were found in the Arctic and brought back after 24,000 years.
Although scientists have revived single cell microbes and bacteria dating back 250 million years, it is thought to be the oldest multicellular creature ever reanimated.
Previously the longest known record for nematode worms staying in cryptobiosis was 25.5 years in the Arctic.
Prof Teymuras Kurzchalia of the Max Planck Institute of Molecular Cell Biology (MPI-CBG) in Dresden, Germany, which carried out the new research, said: “This study extends the longest reported cryptobiosis in nematodes by tens of thousands of years.
“Survival in extreme environments for prolonged periods is a challenge that only a few organisms are capable of.
“Our findings are important for the understanding of evolutionary processes because generations times could be stretched from days to millenia, and long-term survival of individuals of species can lead to the refoundation of otherwise extinct lineages.”
Genetic analysis shows the ancient worms belong to a previously unknown species, which has been named Panagrolaimus kolymaensis.
Lying dormant for decades
The team found the species contained similar genes to other worms that can enter a state of suspended animation, including those that increase a sugar called trehalose, which may help them to survive harsh drying-out and freezing.
Experts say that the study proves that the worms can lie dormant not just for decades, or hundreds of years, but entire geological eras, waiting for conditions to improve.
Dr Vamshidhar Gade of the MPI-CBG, said: “Overall, our research demonstrates that nematodes have developed mechanisms that allow them to preserve life for geological time periods.”
Several ancient species have been revived in recent years. In 2020, Japanese and US scientists reanimated 200-million-year-old microbes found in sediments 328ft (100m) beneath the ocean floor within the South Pacific Gyre, an ocean current.
The findings do not show that life can lie waiting in the most extreme environments on Earth but gives new hope that it could be found on inhospitable planets, such as Mars and other parts of the solar system.
However, some scientists have cautioned against reanimating “time-travelling” species, warning that it could unleash ancient bugs or viruses that could threaten human health and the environment.
There are fears that global warming may cause glaciers and permafrost to melt, allowing long dormant microbes to re-emerge.
A new study in Plos by the European Commission Joint Research Centre used artificial intelligence to simulate what would happen if ancient viruses were unleashed onto modern communities.
They found that ancient invading pathogens could often survive and evolve in the modern community with 1 per cent capable of wiping out one third of the species.
The nematode study was published in the journal Plos Genetics.