There’s hibernation and then there’s this.
Scientists say they have managed to wake up roundworms asleep for 46,000 years, according to a new analysis published Thursday in PLOS Genetics. The worms were pulled out of the Siberian permafrost, 40 metres below the surface, where they stayed frozen but alive in a “state of suspended metabolism called cryptobiosis.”
By very slowly and gently thawing the roundworms, also called nematodes, researchers were able to get them to the point where they could wriggle around, eat and even reproduce.
One of the worms was bred in a lab for 100 generations, after researchers found that the species could reproduce parthenogenetically, or without a male partner.
The study published Thursday builds on prior research published in 2018, which estimated that the roundworms dated back 42,000 years and belonged to two genera: Panagrolaimus and Plectus.
But by radiocarbon dating plant matter found with the worms, researchers say they could get an even more precise date of 46,000 years old. The worms were found in a prehistoric burrow left by arctic gophers of the genus Citellus, they wrote.
The research team also conducted a new genetic analysis of the worms and found that the Panagrolaimus worms belonged to a completely new species. The team named the new worm Panagrolaimus kolymaensis, for the Kolyma River near where it was found.
It’s possible that these nematodes have been asleep since the Pleistocene, meaning these tiny worms have “evolved mechanisms potentially allowing them to suspend life over geological time scales,” the report reads, adding that these results could one day lead to improved conservation efforts for endangered species, especially in the face of global warming and extreme heat.
“Our findings are essential for understanding evolutionary processes because generation times can range from days to millennia,” concludes Philipp Schiffer, one of the authors who oversaw the study.
But not all scientists are convinced these roundworms really travelled tens of thousands of years in time.
“I don’t doubt the age of the organic material in the permafrost,” Byron Adams, a biologist at Brigham Young University told Scientific American. “Those values are likely legit.”
He doesn’t believe the authors of the study have done enough work to show that the roundworms in their permafrost sample “are not simply surface contaminants.”
Study co-author Teymuras Kurzchalia, a cell biologist emeritus at the Max Planck Institute, told Scientific American that while he was not there when the samples were extracted in 2002, he trusts the scientists who were, and believes the sterility procedures used were enough to prevent contamination.
If the roundworms really are 46,000 years old, that would blow the previous record out of the water. Before this, the oldest roundworm to be revived from cryptobiosis had been dried up on a preserved plant sample for 39 years. Another notable roundworm was frozen on moss in the Antarctic for 25 and a half years.
The sheer length of time these worms survived is causing even scientists’ heads to spin.
“This raises the question of whether there is an upper limit to the length of time an individual can remain in the cryptobiotic state,” the study reads.
A comparison of the P. kolymaensis worm with a common nematode species used in labs found that the two species used the same chemical mechanisms to enter cryptobiosis.
The common dauer larva must process a sugar called trehalose in order to survive being frozen. A genetic analysis found that the genes required for this process were also present in the ancient P. kolymaensis.
“This survival kit is the same as it was 46,000 years ago,” Kurzchalia says.
These results are particularly exciting because, as the world continues to face record-breaking heat, it could be invaluable to know how some animals are able to survive such extremes.
“We need to know how species adapted to the extreme through evolution to maybe help species alive today and humans as well,” Schiffer said.
Comments