An ancient worm has come back to life after 46,000 years frozen in the Siberian permafrost, and has begun to reproduce, in addition, its species was not known until now
These tiny animals, called nematodes, revived from a long slumber that began in the late Pleistocene, between 45,839 and 47,769 years ago, a radiocarbon analysis has revealed. In addition to being impressively tough, these microscopic critters belong to a species unknown to science until now, called Panagrolaimus kolymaensis .
Nematodes, also called roundworms, are one of the few organisms capable of surviving in such extreme environments for long periods of time. To do this, they enter a limbo-like state called “cryptobiosis,” in which all measurable metabolic processes shut down until environmental conditions improve. In 2018, nematodes were resurrected after an alleged 42,000 years of cryptobiosis. With this new finding, the worms beat their own record for several millennia.
Other organisms capable of such a feat are tardigrades and rotifers. An especially startling example of this phenomenon is a bacterial spore preserved in amber between 25 and 40 million years old. In the new study, P. kolymaensis were recovered from 40 meters deep in the permafrost on the banks of the Kolyma River in northeastern Siberia. The frozen soil of these outbacks is home to a trove of unexpected and ancient finds, from archaic DNA and viruses to an entire bear.
Radiocarbon analyzes of plant material from permafrost samples placed them in the Late Pleistocene, and genomic analyzes of the nematodes identified them as an undescribed species. The researchers cultured the worms for more than 100 generations and compared their genome with that of one of their living relatives, Caenorhabditis elegans , to identify common genes involved in cryptobiosis.
In doing so, they hope to better understand the mechanisms underlying this mysterious state, which could eventually lead to new methods of long-term storage of cells and tissues. They are also curious if there is an upper limit to how long nematodes can remain in the cryptobiotic state.
“These findings have implications for our understanding of evolutionary processes, as generation times can stretch from days to millennia, and the long-term survival of individuals of species can lead to the refounding of lineages that would otherwise go extinct.” the authors conclude.