Unlocking Ancient Secrets: Woolly Mammoth's RNA Tells a Tale

Deep in the Siberian permafrost, a young woolly mammoth named Yuka lay frozen for roughly 40, 000 years. In 2010, tusk hunters found Yuka's remarkably preserved body, with skin, muscle tissue, and even hair still intact. Scientists were thrilled, as Yuka's DNA was in such good shape that some cell nuclei could start limited activity when placed in mouse eggs. However, cloning Yuka was not possible. Recently, a team of researchers achieved something extraordinary: they sequenced Yuka's RNA. This is a big deal because RNA is usually too fragile to survive long after an organism dies. The team ground up bits of Yuka's muscle and other tissue, then used special chemical treatments to extract any remaining RNA fragments. Previous attempts with very old specimens had either failed or been contaminated, so this was a significant breakthrough. The researchers used methods adapted for ancient, fragmented RNA molecules. This allowed them to explore information that had never been accessible before, such as which genes were active when Yuka died. They found that Yuka's muscles were tensing and its cells were signaling distress in its final moments, likely due to a cave lion attack. Studying RNA provides a unique perspective that DNA alone cannot offer. "With RNA, you can access the actual biology of the cell or tissue happening in real time within the last moments of life of the organism, " said Emilio Mármol, a researcher who led the study. Combining DNA and RNA analysis led the team to discover that Yuka, usually described as a juvenile female based on external anatomy, is actually a male. Both molecules contained sequences derived from the Y chromosome, which only males have. While scientists have studied DNA from creatures that lived up to 2 million years ago, RNA sequencing has lagged far behind. RNA normally breaks down very quickly, unlike DNA, which is more stable. However, if a cell is frozen, as in many Ice Age remains, the degradation process halts. This means that RNA can be preserved for much longer periods in cold, dry environments. Now that scientists have demonstrated that it's possible to recover such old RNA, the same technique could be applied to samples from other long-extinct species. This could help us understand more about these ancient creatures and even detect if they were infected with RNA-based viruses like influenza or coronavirus when they died. The method could also be applied to remains of the ancestors of still-living species. This could provide a more comprehensive understanding of the effects of population decline and help pull today's threatened species back from the brink of extinction. Studying ancient RNA in combination with DNA and protein opens a new window into lost worlds.