Ancient RNA expression profiles from the extinct woolly mammoth
The analysis of ancient DNA has recently gained considerable momentum, allowing the study of extinct and extant organisms that lived up to 2 million years ago. This has enabled the reconstruction of genomes and historical ancestry of multiple extinct species, as well as revealing the complex nature of the bygone ecosystems where they once thrived. However, current DNA sequencing techniques cannot alone provide information about tissue identity, gene expression dynamics or transcriptional regulation (all of which is encoded in the RNA fraction, and critical to fully understanding the biology of these now lost species). Here we report RNA expression profiles from 10 woolly mammoths dating to the Late Pleistocene. One of these, dated to ~39,000 YBP, yielded sufficient detail to recover tissue-specific biological functions essential for skeletal muscle and skin metabolism. Our findings represent the oldest ancient RNA sequences recorded to date, enabling the reconstruction of transcriptional signatures in the extinct woolly mammoth. With our results, we showcase the potential to study ancient RNA molecules decoding preserved transcriptomes from deep time, pushing the field beyond the study of ancient DNA and proteins, and anticipating a new era of integrative palaeo-studies combining genomics, proteomics and transcriptomics.