These studies usually rely on the DNA of bones and teeth, which can store DNA and protect it from environmental pollution. However, this kind of skeleton remains is extremely rare, which makes it impossible to carry out genetic analysis for most of human history.
In order to fill these gaps, researchers at Max Planck Institute for Evolutionary Anthropology adopted a new method to enrich and analyze human nuclear DNA from sediments, which are abundant in almost every archaeological site.
So far, only mitochondrial DNA has been recovered from archaeological sediments, but it is of limited value for studying population relations. The appearance of DNA analysis of sediment nuclei provides a new opportunity for studying human past. However, when extracting ancient human DNA from sediments, scientists must be careful not to extract large amounts of DNA from other mammals, such as bears and hyenas.
Benjamin Vernot, the first author of this study, said, "For example, there are many places in the human genome that are very similar to bear DNA." Researchers specialize in genomic regions, and they are confident that only human DNA can be isolated. They also designed some methods to measure how to successfully remove non-human DNA.
Scientists used their technology to study more than 50 sediment samples from three caves. In two of these caves-Chagyrskaya and Denisova caves in Altai Mountain in southern Siberia-previous studies analyzed the DNA of bones. Therefore, the author can compare the DNA in sediments with that in bones.
Matthias Meyer, a senior author of the study, said: "The technology we developed is very novel, and we hope to test it where we know what will happen." The researchers found that the DNA in the sediment was most closely related to the genome obtained from the bones in these parts, which made them confident in the reliability of this method.