Scientists have recovered ancient RNA from a juvenile mammoth named Yuka, who lived approximately 40,000 years ago in present-day Siberia. This groundbreaking discovery offers new insights into the final moments of the extinct creature’s life. The RNA was extracted from well-preserved mummified leg tissue, which had remained intact in permafrost for millennia. This RNA discovery marks the oldest ever sequenced, providing a unique window into the biological processes occurring in Yuka’s cells at the time of its death.
Revealing Insights into Mammoth Biology
Researchers extracted RNA to determine which genes were active when Yuka died. According to Love Dalén, a professor of evolutionary genomics at the Centre for Palaeogenetics at Stockholm University, the significance of RNA lies in its role as a messenger that regulates gene expression within different cell types. As he explained, “All the cells in an organism have the same DNA, but what makes them different is essentially the RNA.”
While ancient DNA can endure for over 1 million years, RNA has traditionally been viewed as more fragile. The techniques employed in this study provide a promising avenue for future research, although their effectiveness on less well-preserved specimens remains uncertain.
The research team examined ten samples of frozen mammoth tissue, including muscle and skin. Only three yielded RNA fragments, with one sample producing sufficient data to analyze the mammoth’s gene activity. This sample, belonging to Yuka, was discovered in 2010 in Oyogos Yar, northeastern Siberia.
Revelations from RNA Analysis
From their analysis, researchers identified messenger RNA, which is crucial for protein coding, and microRNA, which regulates gene activity. According to Emilio Mármol Sánchez, the study’s lead author and postdoctoral researcher at the University of Copenhagen, this data reveals the biological processes occurring in Yuka’s cells just before its death.
The findings suggest that Yuka was likely close to death, evident in the metabolism of its muscle tissue. The active proteins identified included titin, associated with muscle elasticity, and nebulin, which plays a role in skeletal muscle contraction. “The muscle-specific microRNAs we found in mammoth tissues are direct evidence of gene regulation happening in real time in ancient times,” said Marc Friedländer, a co-author of the study.
The research indicates a predominance of slow-twitch muscle fibers in Yuka’s tissue, suggesting the last activity of the mammoth’s muscle before death. This research represents a significant step in understanding the biology of extinct species and the potential applications of ancient RNA studies.
While this discovery is remarkable, it is part of a broader context of studying ancient RNA. In 2023, Mármol Sánchez led a study on RNA from a 130-year-old Tasmanian tiger. In 2019, RNA was sequenced from a 14,300-year-old wolf preserved in permafrost. The study of Ötzi the Iceman, a 5,300-year-old mummy found in the Alps, also revealed RNA, indicating a growing interest in ancient biological materials.
The potential applications of this research extend beyond understanding extinct species. According to Dalén, the techniques developed could assist in efforts to revive extinct animals, such as those being pursued by Colossal Biosciences, a biotech company aiming to “resurrect” species like the mammoth and dodo through genome editing of their closest relatives.
As the field of ancient RNA research develops, it may open new avenues for studying the evolution of ancient viruses and pathogens. The successful sequencing of mammoth RNA is a pivotal moment, yet the long-term implications of this research remain to be fully understood. As Erez Lieberman Aiden, a professor of biochemistry and molecular biology at the University of Texas Medical Branch, remarked, it is still early to determine how this will shape the future of ancient biological studies.
In conclusion, the sequencing of RNA from Yuka not only enhances our understanding of mammoths but also sets a precedent for future explorations into the biology of ancient organisms.
