MADRID, Dec 28 (EUROPA PRESS) -Ancient human and animal DNA manages to be preserved in archaeological sediments because it is concentrated in small "hot spots", especially in microscopic particles of bone or feces.It is the finding published in the Proceedings of the National Academy of Sciences (PNAS) by an international team of researchers who have succeeded in isolating DNA from solid blocks of undisturbed sediments embedded in plastic resin.Micro-sampling of these particles can recover substantial amounts of DNA from ancient humans, such as Neanderthals, and other species and link them to archaeological and ecological records on a microscopic scale.The sediments in which archaeological finds are embedded have long been regarded by most archaeologists as unimportant by-products of excavations.However, in recent years it has been shown that sediments can contain ancient biomolecules, including DNA."Obtaining human DNA and ancient fauna from sediments offers new and interesting opportunities to investigate the geographical and temporal distribution of ancient human beings and other organisms in sites where their skeletal remains are scarce or absent," he says in a statement from Matthias Meyer, lead author of the study and researcher at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.To investigate the origin of DNA in sediments, the Max Planck researchers partnered with an international group of geoarchaeologists - archaeologists who apply geological techniques to reconstruct sediment and reservoir formation - to study DNA conservation in sediments on a microscopic scale. .They used blocks of undisturbed sediment that had been previously mined from archaeological sites and soaked in plastic-like synthetic resin (polyester).The hardened blocks were brought to the lab and cut into sections for microscopic imaging and genetic analysis.The researchers were able to extract DNA from a collection of sediment blocks prepared over 40 years ago, from deposits in Africa, Asia, Europe and North America."The fact that these building blocks are an excellent source of ancient DNA - including that from hominids - despite the fact that they have often been stored for decades in plastic, provides access to a vast repository of untapped genetic information."The study opens a new era of studies on ancient DNA that will revisit samples stored in laboratories, allowing analysis of deposits that have long been refilled, which is especially important given the restriction of travel and the inaccessibility of sites in a pandemic world, "says Mike Morley of Australia's Flinders University, who led some of the geoarchaeological analyzes.The scientists used blocks of sediment from Denisova Cave, a site in the Altai Mountains of south-central Siberia, where ancient DNA has been recovered from Neanderthals, Denisovans and modern humans, and showed that the small organic particles they produced more DNA than randomly sampled sediments."The study clearly shows that the high success rate in the recovery of ancient mammalian DNA from Denisova Cave sediments is due to the abundance of micro-debris in the sediment matrix, rather than free extracellular DNA from faeces. , body fluids or decomposing cellular tissue potentially adsorbed to mineral grains ", states Vera Aldeias, co-author of the study and researcher at the University of Algarve (Portugal)."This study is a great step towards understanding precisely where and under what conditions ancient DNA is preserved in sediments," Morley adds.The method described in the study allows for a very localized microscale sampling of the sediments to analyze the DNA and demonstrates that the ancient DNA (ADNa) is not evenly distributed in the sediments, and that certain characteristics of the sediments are more conducive than others for the preservation of ancient DNA."Linking the ADNa in sediments to the archaeological microcontext means that we can also address the possibility of physical movement of ADNa between sedimentary deposits," stresses Susan Mentzer, researcher at the Senckenberg Center for Human Evolution and the Paleoenvironment (Germany).Diiendo Massilani, lead author of the study, was able to recover substantial amounts of Neanderthal DNA from just a few milligrams of sediment.He was able to identify the sex of the individuals who left their DNA and showed that they belonged to a population related to a Neanderthal whose genome was previously reconstructed from a bone fragment discovered in the cave."The Neanderthal DNA in these small samples of sediment embedded in plastic was much more concentrated than what we usually find in loose material - he says -. With this approach it will be possible in the future to analyze the DNA of many ancient human individuals different from starting from just a small cube of solidified sediment. It's funny to think that this is presumably so because they used the cave as a toilet tens of thousands of years ago. "© 2021 Notimérica.The redistribution and redistribution of all or part of the contents of this website without your prior and express consent is expressly prohibited.