DNA from extinct humans discovered in cave sediments
DNA from extinct humans discovered in cave sediments
Researchers have developed a new method to retrieve hominin DNA from cave sediments -- even in the absence of skeletal remains
esearchers found the genetic material in sediment samples collected from seven archaeological sites.
The
remains of ancient humans are often scarce, so the new findings could
help scientists learn the identity of inhabitants at sites where only
artefacts have been found.The results are described in Science.
Antonio Rosas, a scientist at Spain's Natural Science Museum in Madrid, said: "This work represents an enormous scientific breakthrough.
"We can now tell which species of hominid occupied a cave and on which particular stratigraphic level, even when no bone or skeletal remains are present."
"We know that several components of sediments can bind DNA," said lead researcher Matthias Meyer of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
"We therefore decided to investigate whether hominin DNA may survive in sediments at archaeological sites known to have been occupied by ancient hominins."
The team collaborated with researchers excavating at seven dig sites in Belgium, Croatia, France, Russia and Spain.
They collected sediment samples covering a time span from 14,000 to 550,000 years ago.
By looking into the genetic composition of our extinct relatives, the Neandertals, and their cousins from Asia, the Denisovans, researchers can shed light on our own evolutionary history. However, fossils of ancient humans are rare, and they are not always available or suitable for genetic analyses. "We know that several components of sediments can bind DNA," says Matthias Meyer of the Max Planck Institute for Evolutionary Anthropology. "We therefore decided to investigate whether hominin DNA may survive in sediments at archaeological sites known to have been occupied by ancient hominins."
To this aim Meyer and his team collaborated with a large network of researchers excavating at seven archaeological sites in Belgium, Croatia, France, Russia and Spain. Overall, they collected sediment samples covering a time span from 14,000 to over 550,000 years ago. Using tiny amounts of material the researchers recovered and analyzed fragments of mitochondrial DNA -- genetic material from the mitochondria, the "energy factories" of the cell -- and identified them as belonging to twelve different mammalian families that include extinct species such as the woolly mammoth, the woolly rhinoceros, the cave bear and the cave hyena.
The researchers then looked specifically for ancient hominin DNA in the samples. "From the preliminary results, we suspected that in most of our samples, DNA from other mammals was too abundant to detect small traces of human DNA," says Viviane Slon, Ph.D. student at the Max Planck Institute in Leipzig and first author of the study. "We then switched strategies and started targeting specifically DNA fragments of human origin." Nine samples from four archaeological sites contained enough ancient hominin DNA for further analyses: Eight sediment samples contained Neandertal mitochondrial DNA from either one or multiple individuals, while one sample contained Denisovan DNA. Most of these samples originated from archaeological layers or sites where no Neandertal bones or teeth were previously found.
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