Scientists Isolate 39,000-Year-Old RNA from Woolly Mammoth

Researchers have successfully isolated and sequenced the oldest known RNA from a juvenile male woolly mammoth that lived approximately 39,000 years ago in Siberia. The mammoth, named Yuka, was discovered in 2010 in the permafrost along the Oyogos Yar coast near the Laptev Sea. This groundbreaking achievement sheds light on the biological processes of Ice Age megafauna and challenges previous assumptions about the longevity of RNA.

This study reveals that RNA, a molecule essential for biological functions, can endure much longer than previously believed. The RNA recovered from Yuka not only identifies genes that were active in the mammoth’s tissues at the time of its death but also indicates signs of cell stress. Most of what scientists know about prehistoric organisms comes from skeletal remains, which have limitations in revealing their biology. The ability to extract and analyze biomolecules like RNA offers a new avenue for understanding these ancient creatures.

According to Emilio Mármol, a geneticist and the lead author of the study from the University of Copenhagen, “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.” This access provides a detailed view of the cellular metabolism of woolly mammoths, something that DNA or protein analysis alone cannot achieve.

Understanding Ancient Biology Through RNA

RNA, or ribonucleic acid, plays a crucial role in cellular functions by acting as a messenger between an organism’s genome and its cellular machinery. It regulates which genes are expressed and influences various metabolic processes. The researchers found RNA molecules in Yuka that code for proteins involved in muscle contraction and metabolic regulation under stress, potentially related to injuries sustained from an attack by a cave lion, an extinct species closely related to today’s African lion. Love Dalén, a geneticist and co-author of the study from Stockholm University, noted that the markings found on Yuka were not severe enough to have caused its death, leaving the cause of its demise uncertain.

The study also highlights that RNA is more fragile than DNA and proteins. Previously, the oldest RNA recovered was from a wolf cub that lived around 14,000 years ago. The oldest DNA, in contrast, has been found in samples dating back almost 2 million years, while ancient proteins have been extracted from remains dating up to 23 million years ago. The findings from Yuka demonstrate that, under the right conditions, RNA can survive much longer than scientists once thought, particularly in the frigid conditions of Siberia.

A New Era of Paleogenetics

The resequencing of Yuka’s DNA further confirmed its sex as male, which was previously misidentified as female. Standing at approximately 1.6 meters at the shoulder, Yuka represents a significant addition to the understanding of woolly mammoths’ biology and physiology. Researchers believe that RNA could potentially be recovered from even older remains, opening new avenues for studying gene expression patterns in other ancient species.

Mármol emphasized the implications of these findings, stating, “We hope our work elicits a renewed interest in exploring RNA in other old remains, not necessarily from the Ice Age or extinct species, but also from medieval or historical remains of both extinct and extant organisms.” This research not only deepens our understanding of woolly mammoths but also paves the way for future studies in paleogenetics, potentially transforming how scientists approach the study of ancient life.