Scientists have revived dormant roundworms frozen for 46,000 years in northern Siberia.
The long-extinct creatures had survived by slowing their metabolic rates to close to zero. It allowed them to withstand extreme temperatures, and do without water or oxygen. Studies had previously shown that this dormant state, called cryptobiosis, could keep roundworms alive for around 40 years. Yet these individuals shared the planet with saber-toothed tigers and woolly mammoths.
Like Sleeping Beauty, but much older
After thawing the worms, the scientists revived two simply by rehydrating them with water. They then dated plant material from the permafrost sample using radiocarbon analysis. They concluded that the ice had not thawed since at least 45,839 years ago.
“That [they] could be reanimated after 46,000 years left me absolutely flabbergasted,” said Teymuras Kurzchalia, senior author of the worms study. “It is rather like the fairy tale of Sleeping Beauty, but over a far longer period.”
Having reanimated the worms, the scientists still needed to discover whether it was a known species. Genetic analysis eventually showed that the worms belonged to a novel and long-extinct species, which researchers have named Panagrolaimus kolymaenis.
The dethawed roundworms. Photo: Shatilovich et al., PLOS Genetics, 2023/CC-BY 4.0
Interestingly, P. kolymaenis had a number of overlapping genes with a living species, Caenorhabditis elegant.
“These findings have implications for our understanding of evolutionary processes, as generation times may be stretched from days to millennia,,” the study states. “And long-term survival of individuals of species can lead to the foundation of otherwise extinct lineages.”
