Scientists Sequence 20-Million-Year-Old Rhino Proteins, Shifting Evolution Timeline

Two studies published in Nature have recovered and sequenced the oldest known proteins, pushing the molecular record of life back more than 20 million years. An international team led by the University of Copenhagen extracted partial sequences of seven enamel proteins from a rhinoceros tooth found in the High Arctic’s Haughton impact crater on Devon Island, Canada, dated at 21–24 million years. A companion study headed by Harvard University analysed mammal teeth from Kenya’s Turkana Basin, retrieving enamel peptides up to 18 million years old from ancestral rhinos, elephants and hippos despite the region’s hot climate. The work extends the previous age limit for authenticated ancient proteins—about four million years—by at least a factor of five and demonstrates that enamel can preserve informative biomolecules in both polar and tropical settings. Phylogenetic analysis of the Canadian specimen revises the rhinocerotid family tree, indicating that the genus Epiaceratherium diverged earlier than fossil morphology alone had suggested. The findings open a path to exploring evolutionary relationships far beyond the reach of ancient DNA, which rarely survives more than one million years, and raise the prospect of obtaining molecular insights from even older fossils, potentially including dinosaurs.