This package of the project seeks to explain for whom this burial practice was chosen. Who were the people given these unusual gypsum burials? Were they local residents, immigrants, or people of special status? Was this burial method used for people who experienced disease?
These team members are specialised in a range of methods that will allow us to determine the age, sex and health of the dead, what they ate throughout their lives, their genetic ancestry, and their potential geographic origins. Understanding whether these individuals were from the local area or travelled to York from other regions will help us determine if this burial custom was developed locally or brought to York from elsewhere.
Reading the Bones
Skeletons in York, Doncaster, Castleford-Wakefield and Sherburn in Element will have their bones analysed to determine the age and sex of these individuals as well as look for evidence of pathology visible on the bones and teeth.
Ancient DNA: Unlocking Genetic Stories
Ancient DNA analysis will further assist in determining the genetic sex of these individuals and look for evidence of infectious pathogens. These analyses, performed in the Ancient Genomics Laboratory at the Francis Crick Institute will also explore the genetic ancestries and population affiliations of the individuals chosen for gypsum burials. The results of ancient DNA analysis will generate information on their ancestral origins, and help determine if there are patterns of relatedness with other sampled burials.
Chemical Clues to Origins and Diet
Stable isotope analyses, which acts like a chemical fingerprint, will be performed to identify potential geographic origins of these individuals in comparison to their genetic ancestral origins. Stable oxygen isotope analysis (δ18O) alongside strontium (87Sr/86Sr) and lead (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb) isotope analyses can suggest if an individual may have grown up in the Yorkshire region or identify areas abroad where they could have migrated from.
Stable isotope analyses can tell us more about the way these people lived their lives through their dietary biographies. Stable carbon (δ13C), nitrogen (δ15N) and sulfur (δ34S) isotope analyses will help identify sources of dietary protein, such as the importance of agricultural animals, seafood and plants. We can do this by comparing the stable isotope signatures of the people buried in gypsum to local animals from the area (Sherburn in Elmet, Castleford and Doncaster), therefore, creating a local baseline. We will study how their diets changed over time from birth to late adolescence by performing incremental dentine analyses on adult molar teeth, similar to reading growth rings on trees. This will be compared to the adult diet by sampling bone collagen from adult bone.
Further in-depth characterisation of diet will be made possible by using amino acid compound specific stable carbon and nitrogen isotope analyses. This will be the first application of this technique on humans and animals from the Roman period in the UK and will be complemented by Bayesian isotopic mixing models. These results will allow us to understand baseline shifts in stable isotope analyses that impact our interpretations of bulk stable carbon and nitrogen isotope values.
Looking Deeper into Human Hair
Tresses of human hair surviving from a female gypsum burial will be studied using low-powered microscopes and a high-powered scanning electron microscope (SEM) to identify any plant materials and parasites present within the hair. Identifying these materials could tell us more about the use of this hair ornament and the health of the person wearing it. Further incremental analysis of δ13C, δ15N and δ34S for sections of the hair will provide a dietary history of the individual to whom the hair originally belonged.