The Oldest Human DNA Sequences
Over the past years, genomic sequences have been retrieved from hundreds of ancient human remains as well as those of extinct human relatives such as Neanderthals and Denisovans. However, due to constraints on DNA preservation in non-permafrost environments, genetic analyses of human fossils are usually limited to the Late Pleistocene (the last 125,000 years). Recently, improvements to DNA extraction and library preparation techniques have enabled the reconstruction of a mitochondrial genome sequence as well as small amount of nuclear DNA sequences from the 400,000 year-old hominin remains from Sima de los Huesos, a cave site located within the archeological complex of Atapuerca, Northern Spain. The DNA found in these fossils is even more degraded and sparse than in any other ancient human fossil that has produced genetic data to date. I will discuss the technical difficulties one has to face when working with poorly preserved ancient material and the insights this work provides into human evolution in the Middle Pleistocene.