Neanderthal DNA Found In Cave Dirt Even Though The Bones Are Long Gone
Researchers have detailed a method by which it is possible to detect the presence of long-gone hominin groups in locations where actual skeletal remains aren't present. The method — which involves looking for traces of DNA in sediment layers — has been successfully used to detect the presence of Neanderthal DNA in more than half a dozen sediment layers, as well as an instance of Denisovan DNA detection in what is described as a Middle Pleistocene layer.
Knowing which hominin groups occupied any given archaeological site is important in helping shape current knowledge about the site itself, migration, and more. However, the absence of skeletal remains has largely meant that this knowledge was beyond most researchers who, at best, could detect early human presence in the form of tools, sawed bones, and similar.
According to a new study published in Science Mag, that limitation is changing. By looking for trace DNA in sediment layers, researchers are able to determine which ancient hominin once occupied a site, including the presence of long-gone Denisova hominin and Neanderthals. The trace DNA of the aforementioned Neanderthals were found in four caves located through Eurasia, while the Denisovan DNA was found in Denisova Cave in what researchers describe as a near-bottom layer of Middle Pleistocene sediment.
The discovery of Denisovan DNA is particularly important due to the scarcity of knowledge related to these ancient human relative. Based on what is currently known, researchers believe the Denisovans existed in a stretch of land spanning from SE Asia to Siberia where Denisova Cave is located. Research issues are compounded by the relative lack of skeletal remains pertaining to both the Denisova and the Neanderthals.
Overall, the researchers say that 'cave sediments represent a rich source of ancient mammalian DNA,' and that among that DNA is typically trace amounts pertaining to ancient human ancestors. This remains true even if no skeletal remains have been found at the site. As such, this technology could help researchers discover which hominins were present at archaeological sites where only tools and other signs of past life were found.
SOURCE: Science Mag