NGS Digs up Ancient Mummy DNA
It was previously believed that ancient Egyptian mummies did not have any viable DNA available for sequencing. Possibly due to the hot climate or the chemicals used in mummification, several attempts to extract DNA were unsuccessful. However a team of ancient DNA specialists has successfully sequenced genomes from 90 ancient Egyptian mummies. Until now, the most recent success was a 2010 study that performed polymerase chain reaction on 16 mummies. However, PCR cannot always distinguish between ancient DNA and modern contamination.
Johannes Krause, a geneticist at the Max Planck Institute for the Science of Human History in Jena, Germany, used next generation sequencing to read stretches of DNA and identify any that resemble human DNA. The complete reads allowed the team to piece together data that had tell tale markers of ancient DNA. The results were more reliable than the previous PCR study.
The mummy’s soft tissue contained almost no DNA, but the bones and teeth were full of genetic material. Ninety of the mummies yielded mitochondrial DNA, but this left out the DNA inherited from the father. The nuclear genome, which contains DNA from both parents, is far more informative. Unfortunately, only a small number of mummy nuclear genome was viable, and even fewer passed strict contamination tests. The team ended up with only three nuclear genomes from mummies of different time periods.
They discovered that ancient Egyptians are genetically linked to ancient and modern Near Eastern populations and the genetics remained consistent even as different powers conquered the empire. However, 15% to 20% of modern day Egyptians reflect sub-Saharan ancestry, something not found in ancient Egyptian genome. Krause suspects increased trade along the Nile or the spread of Islam in the Middle Ages increased contact between northern and sub-Saharan Africa.
Geneticist Iosif Lazaridis of Harvard Medical School points out that the genome sequencing of these ancient mummies is a big accomplishment but may not be representative of ancient Egypt as a whole. Other regions may have been more impacted by conquests and various historical events. However, the possibilities are endless now that it has been proven that DNA can be successfully extracted and sequenced from ancient mummies.