Ancient DNA and protein preservation and transfer in concretions covering human remains

Archaeological remains covered with concretions, including human bones, are commonly found in certain areas and time periods of interest for understanding the past, but have yet to be investigated for potential ancient DNA (aDNA) and protein content. We extracted aDNA and proteins in tandem from human dental remains and the concretions surrounding them and compared them to non-concreted human dental remains from the same site as well as postcranial human remains from a contemporary site. Our study shows that both the original element and concretions lacked endogenous human aDNA. Interestingly, concretions covering human tissues in two cases were found to contain human oral microbiome genomic data leached from the original skeletal source, as well as environmental and human proteins. In conclusion, we show that when investigating the preservation of certain species in singular environments, this substrate can be a source of microbial reads and may be utilised to study ancient microbial genomes.