Neanderthal DNA extracted from sediments offers new insights into their migrations

Excavation in the Galería de las Estatuas cave site (Photo courtesy Javier Trueba - Madrid Scientific Films. All rights reserved)
Excavation in the Galería de las Estatuas cave site (Photo courtesy Javier Trueba – Madrid Scientific Films. All rights reserved)

An article published in the journal “Science” reports the extraction of nuclear DNA belonging to Neanderthals from sediments excavated in deposits in northern Spain and Siberia. A team of researchers led by Benjamin Vernot of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, used techniques to extract DNA from sediments developed over the past few years. At the Spanish site, this made it possible to discover DNA linked to different Neanderthal populations with one population being replaced by another about 100,000 years ago.

Paleogenetics, the discipline that studies the DNA of extinct species and in particular of ancient human beings, is bringing about great progress in the reconstruction of the history of humanity. However, hominin bones in sufficient conservation to allow for the extraction of DNA fragments are rare. In April 2017, an article published in the journal “Science” described a new method for collecting DNA from sediments found in archaeological sites, even when no bone remains are present. Initially, only mitochondrial DNA was extracted but its value was limited. New developments in this method of extracting DNA from sediments now made it possible to obtain nuclear DNA as well, which tells us much more about who the inhabitants of those sites were.

Various traces of hominin DNA have been found in the Chagyrskaya and Denisova caves in Siberia, the analysis of which showed a close relationship with individuals whose DNA was obtained in the past from very well preserved bones. The situation is very different in Spain, on the site known as Galería de las Estatuas. There, only the bone of a toe attributed to a Neanderthal was discovered along with stone tools with an age between 70,000 and 115,000 years ago. In this case, the discovery of DNA in the sediments told a complex story of two different populations who lived in the cave with the original one replaced by another about 100,000 years ago.

Another discovery resulting from the analysis of Neanderthal DNA discovered in the sediments is in the genetic differences that indicate two events of genetic diversification that gave rise to the two different populations that lived in the Galería de las Estatuas. There are hypotheses about possible links between those diversifications and climate changes and morphological changes in Neanderthals but more data will be needed to establish that.

Matthias Meyer, one of the world’s foremost paleogeneticists, explained that these new techniques for analyzing DNA found in sediments enormously extend the range of options for gaining new insights into the evolutionary history of ancient humans. Now it will be possible to study the DNA of many more populations and from many more places than was previously possible.

These first tests of the latest developments in techniques for obtaining DNA from sediments gave excellent results and justify Matthias Meyer’s optimism. The DNA of very ancient humans that ended up in sediments in which hair or scales of skin got mixed adds new possibilities that it lasts long enough to offer new information on the migrations and interbreedings of ancient human populations.

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