Sequencing of various DNA fragments from skeletal remains has given us a clear understanding of the genetic history of humans. Frequently, ancient DNA (often referred to as aDNA) samples come from recovered bone, teeth, or hair samples. Now, researchers from the University of Vienna have found that cave sediments can preserve ancient DNA well enough to provide genome-length information.
The samples were recovered from the caves of Satsurblia, Georgia where humans lived during the Paleolithic period. The study retrieved samples of three mammalian DNA from a single soil sample. The first genome was of Eurasian ancestry, characteristic of post-ice-age people living in the Near East, North Africa, and parts of Europe. The second was from an unknown extinct species of wolves and dogs, and the last genome was a European Bison.
It’s understood that the DNA remains were preserved in clay-rich sediment from the layers of the cave. The researchers were able to directly sequence DNA found in the sediments, rather than the commonly used method of amplifying small amounts of DNA to make sequencing easier. The small amount of genomic material was sufficient for implementing complementary analyses of various mammalian species to dig some of their population histories. Even from small and fragmentary samples, the scientists were able to determine the human was likely female, carrying XX chromosomes. They were able to even make estimates for percentage Neanderthal mixture into this human sample (approximately 1 percent). The wolf and bison species karyotypes were more mixed, indicating the possible presence of multiple individual wolves and bison samples.
They conclude that this method is an alternative to recovering ancient DNA from the skeletal remains and the team has planned to dive deeper into studying the soil sample of Satsurblia cave to determine the relationship between the effect of climatic changes and ancestral human and animal populations.