A tiny animal called the rotifer was revived after 24,000 years in permafrost, writes NewScientist. The simplest organisms, such as bacteria, are able to survive under such conditions for millennia, and nematode worms returned to life after 30,000 years of "freezing". However, this is the first case of resuscitation of such a large rotifer, an animal with a nervous system and a brain. The successful experiment was reported in a publication in the journal Current Biology by employees of the Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences.
In 2015, scientists drilled a well in the permafrost near the Alazeya River, in northeastern Siberia, in Yakutia, and found a rotifer there - a worm-like organism barely visible to the naked eye, which is considered "living dust". When the researchers thawed the animal and gave it food, the rotifer showed activity and the ability to reproduce: such Bdelloidea rotifers are able to clone themselves without a sexual partner.
Scientists believe they have discovered a new species. After sequencing the genome, they found that the discovered creature was similar to one of the known species, the subspecies of which had not been properly identified.
Using mass spectrometry, the researchers dated the organic remains that were found along with the rotifer. They turned out to be from 23 960 to 24 485 years old. This suggests that the rotifer was frozen at the same time.
Probably, modern rotifers also have the ability to survive in a frozen state. Scientists froze several individuals of different modern species, as well as some offspring of the ancient rotifer at -15 ° C, and after a week they all showed the same resistance to freezing.
It is unclear how rotifers do this, the researchers said. It is known that frost-hardy organisms have many survival mechanisms, but all of them are surprisingly poorly understood. It is also unclear how long rotifers and other frost-hardy animals are able to survive in permafrost. It depends on whether their metabolism stops completely or just slows down a lot. If the former is true, then theoretically rotifers can live much longer than 24,000 years - the duration depends only on the surrounding radiation, which should slowly damage their DNA. But if the metabolism only slows down, then sooner or later the animals will need a source of energy - food to keep moving.