Scientists revive prehistoric worm that laid dormant for 46,000 years

The ancient nematode survived for 46,000 years in the permafrost by entering a state of cryptobiosis.

 Group of nematodes. (photo credit: Wikimedia Commons)
Group of nematodes.
(photo credit: Wikimedia Commons)

Researchers from the European countries of Germany, Ireland, Russia, and the UK documented the discovery and revival of a nematode that had been laying dormant in the Siberian permafrost for some 46,000 years.

The findings of the research are documented in a study published in PLOS Genetics, an open-access, peer-reviewed scientific journal.

“Some organisms in nature have developed the ability to enter a state of suspended metabolism called cryptobiosis when environmental conditions are unfavorable,” the authors of the study write. “Recently, nematode individuals have been reanimated from Siberian permafrost after remaining in cryptobiosis.”

These nematodes belong to two taxonomical genus groups Panagrolaimus and Plectus. However, the nematodes recovered after nearly 50,000 years of permafrost dormancy belong to a previously undescribed species of nematode within the Panagrolaimus genus. 

Researchers have dubbed these nematodes Panagrolaimus kolymaensis.

 A river in Siberia. (credit: PIXABAY)
A river in Siberia. (credit: PIXABAY)

Where were the nematodes found?

Researchers extracted the nematodes from a site called Duvanny Yar in northeastern Siberia. The nematodes were collected from an ancient arctic gopher burrow dated to be between 45,839 and 47,769 years old.

The researchers note that the worms have biochemical mechanisms that they use to endure desiccation and freezing. In fact, according to a press release on the research, laboratory experiments revealed that “exposure to mild desiccation before freezing helped prepare the worms for cryptobiosis and improved survival at -80°C.”

The cryptobiosis exhibited by animals such as nematodes fascinates researchers as it enables animals to exist in states of suspended animation that have durations that scientists are yet not able to fully account for.

The state of cryptobiosis reduces metabolic functioning to rates that are undetectable. 

According to the researchers, the longest record of cryptobiosis in nematodes comes from individuals recovered from arctic moss frozen at -20 degrees Celsius. This study, however, “extends the longest reported cryptobiosis in nematodes by tens of thousands of years,” according to the press release. 

The author notes the value of the findings of the research writing, “our findings here are important for the understanding of evolutionary processes because generation times could be

stretched from days to millennia, and long-term survival of individuals of species can lead to the refoundation of otherwise extinct lineages.”