Frozen proof: Oldest RNA extracted from 40,000-year-old mammoth unlocks life secrets

RNA molecules have the capacity to survive the test of time. For the first time, the oldest RNA molecules have been extracted from the 40,000-year-old remains of an Ice Age woolly mammoth. Researchers from Stockholm University extracted the RNA sequences from a juvenile mammoth (named Yuka) that died almost 40,000 years ago.

Its well-preserved tissue remains were found frozen in permafrost in Siberia, Russia. The study showcases the remarkable longevity of RNA, proving that, like DNA and proteins, it can remain preserved for tens of thousands of years. “With RNA, we can obtain direct evidence of which genes are ‘turned on’, offering a glimpse into the final moments of life of a mammoth that walked the Earth during the last Ice Age.

This is information that cannot be obtained from DNA alone,” said Emilio Mármol, lead author. Mammoth s last moments Woolly mammoths, perfectly adapted to the icy plains of Eurasia and North America during the last Ice Age (115,000–11,500 years ago), gradually went extinct as the climate warmed.

Some last individuals survived on remote Arctic islands until as recently as 4,000 years ago. The research on Yuka s frozen muscle identified tissue-specific patterns of gene expression. Of the mammoth s over 20,000 protein-coding genes, only a subset was found to be active.

The RNA molecules found contain instructions for creating proteins essential for muscle contraction and metabolic regulation when the mammoth was experiencing stress. This finding aligns with previous evidence suggesting Yuka met a violent end. “We found signs of cell stress, which is perhaps not surprising since previous research suggested that Yuka was attacked by cave lions shortly before his death,” said Mármol.

Gene regulation in mammoths Perhaps the most exciting finding was the detection of a variety of non-coding RNA (ncRNA) molecules that regulate gene activity, particularly microRNAs (miRNAs) in the mammoth muscle. “The muscle-specific microRNAs we found in mammoth tissues are direct evidence of gene regulation happening in real time in ancient times. It is the first time something like this has been achieved,” said Marc Friedländer, associate professor at the Department of Molecular Biosciences, The Wenner-Gren Institute at Stockholm University, and SciLifeLab.

The identified microRNAs served as a key tool for confirming the authenticity of the findings. Interestingly, the team found rare mutations in certain miRNAs that acted as smoking-gun evidence of their mammoth origin. Furthermore, the RNA evidence alone enabled the detection of novel genes, an achievement never previously accomplished with such ancient remains.

This achievement pushes the boundaries of how far back in time we can sequence RNA, providing brand new molecular details about the biology. “Our results demonstrate that RNA molecules can survive much longer than previously thought. This means that we will not only be able to study which genes are ‘turned on’ in different extinct animals, but it will also be possible to sequence RNA viruses, such as influenza and coronaviruses, preserved in Ice Age remains,” said Professor Love Dalén.

The success of this study advances the field of ancient biological research. Future work will employ a comprehensive approach, merging data from ancient RNA, DNA, proteins, and other biomolecules. This multi-molecule strategy is expected to expand understanding of extinct megafauna by providing a full, integrated picture of their biology. The study was published in the journal Cell on November 14.