Metagenomic analysis is a highly promising technique in paleogenetic research that allows analysis of the complete genomic make-up of a sample. This technique has successfully been employed to archaeological sediments, but possible leaching of DNA through the sequence limits interpretation. We applied this technique to the analysis of ancient DNA (aDNA) from Late Quaternary stalagmites from two caves in Western Georgia, Melouri Cave and Solkota. Stalagmites form closed systems, limiting the effect of leaching, and can be securely dated with U-series. The analyses of the sequence data from the Melouri Cave stalagmite revealed potential contamination and low preservation of DNA. However, the two Solkota stalagmites preserved ancient DNA molecules of mammals (bear, roe deer, bats) and plants (chestnut, hazelnut, flax). The aDNA bearing layers from one of the two Solkota stalagmites were dated to between ~84 ka and ~56 ka BP by U-series. The second Solkota stalagmite contained excessive detrital clay obstructing U-series dating, but it also contained bear bones with a minimum age of ~50 BP uncalibrated years and ancient DNA molecules. The preservation of authentic ancient DNA molecules in Late Quaternary speleothems opens up a new paleogenetic archive for archaeological, paleontological and paleoenvironmental research.
Genome-scale sequencing and analysis of human, wolf, and bison DNA from 25,000-year-old sediment Highlights d A single shotgun-sequenced Pleistocene sediment yielded genomic data of three mammals d Sediment genome sequencing can produce data comparable to that from skeletal remains d A pre-LGM human lineage from the Caucasus was an ancestral component of West Eurasia d 0.01X wolf and bison environmental genomes, suggesting reshaping of populations
Bioinformatic pipelines optimised for the processing and assessment of metagenomic ancient DNA (aDNA) are needed for studies that do not make use of high yielding DNA capture techniques. These bioinformatic pipelines are traditionally optimised for broad aDNA purposes, are contingent on selection biases and are associated with high costs.Here we present a bioinformatic pipeline optimised for the identification and assessment of ancient metagenomic DNA without the use of expensive DNA capture techniques. Our pipeline actively conserves aDNA reads, allowing the application of a bioinformatic approach by identifying the shortest reads possible for analysis (22-28bp). The time required for processing is drastically reduced through the use of a 10% segmented non-redundant sequence file (229 hours to 53). Processing speed is improved through the optimisation of BLAST parameters (53 hours to 48). Additionally, the use of multi-alignment authentication in the identification of taxa increases overall
SummaryArchaeological sediments have been shown to preserve ancient DNA, but so far have not yielded genome-scale information of the magnitude of skeletal remains. We retrieved and analysed human and mammalian low-coverage nuclear and high-coverage mitochondrial genomes from Upper Palaeolithic sediments from Satsurblia cave, western Georgia, dated to 25,000 years ago. First, a human female genome with substantial basal Eurasian ancestry, which was an ancestry component of the majority of post-Ice Age people in the Near East, North Africa, and parts of Europe. Second, a wolf genome that is basal to extant Eurasian wolves and dogs and represents a previously unknown, likely extinct, Caucasian lineage that diverged from the ancestors of modern wolves and dogs before these diversified. Third, a bison genome that is basal to present-day populations, suggesting that population structure has been substantially reshaped since the Last Glacial Maximum. Our results provide new insights into the late Pleistocene genetic histories of these three species, and demonstrate that sediment DNA can be used not only for species identification, but also be a source of genome-wide ancestry information and genetic history.HighlightsWe demonstrate for the first time that genome sequencing from sediments is comparable to that of skeletal remainsA single Pleistocene sediment sample from the Caucasus yielded three low-coverage mammalian ancient genomesWe show that sediment ancient DNA can reveal important aspects of the human and faunal pastEvidence of an uncharacterized human lineage from the Caucasus before the Last Glacial Maximum∼0.01-fold coverage wolf and bison genomes are both basal to present-day diversity, suggesting reshaping of population structure in both species
Takabuti, was a female who lived in ancient Egypt during the 25th Dynasty, c.660 BCE. Her mummified remains were brought to Belfast, Northern Ireland, in 1834 and are currently displayed in the Ulster Museum. To gain insight into Takabuti’s ancestry, we used deep sampling of vertebral bone, under X-ray control, to obtain non-contaminated bone tissue from which we extracted ancient DNA (aDNA) using established protocols. We targeted the maternally inherited mitochondrial DNA (mtDNA), known to be highly informative for human ancestry, and identified 38 single nucleotide variants using next generation sequencing. The specific combination of these SNVs suggests that Takabuti belonged to mitochondrial haplogroup H4a1. Neither H4 nor H4a1 have been reported in ancient Egyptian samples, prior to this study. The modern distribution of H4a1 is rare and sporadic and has been identified in areas including the Canary Islands, southern Iberia and the Lebanon. H4a1 has also been reported in ancient samples from Bell Beaker and Unetice contexts in Germany, as well as Bronze Age Bulgaria. We believe that this is an important finding because first, it adds to the depth of knowledge about the distribution of the H4a1 haplogroup in existing mtDNA, thus creating a baseline for future occurrences of this haplogroup in ancient Egyptian remains. Second, it is of great importance for archaeological sciences, since a predominantly European haplogroup has been identified in an Egyptian individual in Southern Egypt, prior to the Roman and Greek influx (332BCE).
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