The fate of lipids in archaeological burials

Geochemical techniques have been developed in order to systematically analyse soils collected from several burial sites. Through the extraction and GC analysis of burial soils organic signatures that inform an understanding of the burial environment, including aspects relating to the individual or culture in which they lived, have been obtained. GC analysis revealed that the profiles of several lipid signatures found in the burial soil samples, including n-alkanes, n-alkanals, n-alkanols, fatty acids and steroids, have shown similarities to signatures relating to degraded human adipose tissue and bacterial signatures. The abundance of lipid signatures increases around the skeletal remains, particularly the gut region, which suggests that these components are present because of the remains. Fatty acids and steroids have been typically found in the analysis of tissues from mummies and bog bodies and are also present in adipocere, although the oxidative degradation products (hydroxy fatty acid and diacids) that have also been observed in these tissues have been absent during this study. However fatty acid reduction products such as n-alkanes, n-alkanals and n-alkanols have been observed in several of the graves suggesting that the remains can undergo microbial reduction in the soil. In addition several specific signatures that are exclusive to only a few samples from the remains have provided information on the nature of the burial. The presence of coprostanol in the burial samples has the potential to infer on the individuals last meal, while the presence of specific resin acids within the soil provides information on the materials used to construct a coffin. The presence of pine diterpenoids observed in a burial from Iceland has suggested that materials, such as pine, were imported at the time as pine trees are not native to Iceland. Another specific plant signature, Hopenone b, has further revealed information about the nature of the burial inferring that the plant Cypress Spurge (also known as grave yard weed) was present within close proximity to the grave.