Periodic Reporting for period 1 - MicroStratDNA (Reconstructing Paleolithic Population Dynamics Using Microstratified Paleogenomic Analysis)
Reporting period: 2022-07-01 to 2024-12-31
Our species is defined and sustained by interactions and networks. In Paleolithic contexts, reconstructing interactions and networks is limited to inferences based on material culture or direct evidence of biological relatedness, but evidence on the latter in the form of human fossils is very rare. Still, archaeogenetic research can formulate supra-regional models for broad time periods based on only a few genomes by distinguishing ancient clades, but not to the level of interactions between human groups of particular cultural complexes. Recently, archaeological sediments and speleothems - karstic cave formations - have been revealed as a further genomic archive for past environments and past human populations initiating a new phase in archaeogenetic research. These new archives have the potential to greatly expand the archaeogenetic record as they stem from ubiquitous environmental sources and they do provide the spatial and temporal resolution to zoom into population dynamics at the group level. However, what this ancient DNA (aDNA) originates from and under what conditions it preserves over time are still open questions. The MicroStratDNA project places this paleogenomic data into a microstratigraphic framework, where individual depositional events are recorded in microscopic features, to overcome these problems and to provide high-resolution time series of population interactions. Using an interdisciplinary tool kit, the project is (I) reconstructing the source, origin, and depositional history of sedimentary and speleothem aDNA in archaeological contexts, (II) identifying ideal preservation contexts for this type of aDNA with a focus on in-field assessments and (III) extracting genomic time series from archaeological sediments and speleothems. We are applying this approach predominantly to Upper Paleolithic sites in Georgia to reconstruct the relatedness of the people using individual sites over time and across contemporaneous sites set against regional expressions of climate and paleoenvironment change.
The MicroStratDNA project is concerned with the formation history of ancient sediment DNA (sedaDNA) in archaeological contexts and how we can use this new paleogenetic archive to investigate human population dynamics in the Paleolithic. To this aim, the project contains 4 different work packages – Microcontext, Field Observation, Times Series and Genomic Time Series. All four work packages and several milestones are under way. The core team was formed in Year 1 and 2 with the PI starting an assistant professorship position at the University of Vienna.
The MicroStratDNA projects works with materials collected in previous field campaigns and conducted new sampling and field campaigns at Upper Paleolithic sites in in western Georgia. The Microarchaeology lab at the University of Vienna currently houses 36 block samples from previous campaigns and 55 related thin sections and block chips. This material serves as the starting point for the microcontextual sedaDNA analysis at Satsurblia. We performed microarchaeological and paleogenetic analysis of this material and have identified several microcontexts of variable potential for DNA preservation and integrity. We collected 92 samples for sedaDNA analysis from the blocks and chips. Furthermore, we performed field work at several other cave sites. Field work consisted of block sampling for further microcontextual analysis and bulk sampling of field contexts for sedaDNA based on previous microcontextual analysis combined with field observations. We collected 20 bock samples and 228 sedaDNA samples. First genomic results of the samples from the impregnated blocks and bulk sedaDNA samples show the presence of canid, bovid and human sedaDNA.
The MicroStratDNA projects works with materials collected in previous field campaigns and conducted new sampling and field campaigns at Upper Paleolithic sites in in western Georgia. The Microarchaeology lab at the University of Vienna currently houses 36 block samples from previous campaigns and 55 related thin sections and block chips. This material serves as the starting point for the microcontextual sedaDNA analysis at Satsurblia. We performed microarchaeological and paleogenetic analysis of this material and have identified several microcontexts of variable potential for DNA preservation and integrity. We collected 92 samples for sedaDNA analysis from the blocks and chips. Furthermore, we performed field work at several other cave sites. Field work consisted of block sampling for further microcontextual analysis and bulk sampling of field contexts for sedaDNA based on previous microcontextual analysis combined with field observations. We collected 20 bock samples and 228 sedaDNA samples. First genomic results of the samples from the impregnated blocks and bulk sedaDNA samples show the presence of canid, bovid and human sedaDNA.
The recovery of ancient DNA from sediments greatly expands the scope of archaeogenetic research and presents a new phase in the field. Sediments are ubiquitous at archaeological sites and can therefore expand our current archaeogenetic record greatly, which is currently built on bones. This will also allow us to ask new and much more detailed questions regarding individual sites and regions, using a bottom up approach to population dynamics. However, the major challenge to unlocking this archive is, that we do not yet understand what the extracted DNA originates from. Is the DNA still encased in its original source, for example microscopic bones or biological cells? Are we extracting free DNA in solution? Or has the DNA developed a bond with other materials present in the environmental source? This greatly influences our interpretation as different sedimentary processes are implied for each these possibilities and may affect the integrity of the extracted DNA. The MicroStratDNA projects is proposing a microcontextual approach to sedaDNA to resolve these issues. Only in understanding the context of sedaDNA will we be able to unlock this exciting new archive.