In cave sediments lacking skeletal remains, scientists report having found DNA from ancient humans. The highly sensitive screening technique they applied even identified ancient human DNA sequences from locations where Neandertal presence has been proposed but never demonstrated; thus, say the authors, the technique represents a valuable tool for reconstructing human (and other mammalian species') evolutionary history. To date, DNA analysis from archaic individuals has greatly informed our understanding of evolution. However, fossils from the Pleistocene (often referred to as the Ice Age) have been scarce, impeding scientists' understanding of ancient human movement in this epoch. Vivian Slon et al. decided to investigate whether hominin DNA could survive in sediments at archaeological sites even in the absence of bones. They collected 85 sediment samples from seven Pleistocene sites in Europe and Russia where ancient humans are known to have lived. From the mammalian DNA identified in these samples, they isolated mitochondrial DNA (mtDNA). Large-scale screening of this mtDNA revealed Neandertal DNA in four caves and Denisovan DNA in another. The results may help to establish DNA analyses of sediments as a useful archaeological procedure in the future.
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Science