Bile acids and oxo-metabolites as markers of human faecal input in the ancient Pompeii ruins

Abstract

Small organic molecules, lipids, proteins, and DNA fragments can remain stable over centuries. Powerful and sensitive chemical analysis can therefore be used to characterize ancient remains for classical archaeological studies. This bio-ecological dimension of archaeology can contribute knowledge about several aspects of ancient life, including social organization, daily habits, nutrition, and food storage. Faecal remains (i.e. coprolites) are particularly interesting in this regard, with scientists seeking to identify new faecal markers. Here, we report the analysis of faecal samples from modern-day humans and faecal samples from a discharge pit on the site of the ruins of ancient Pompeii. We propose that bile acids and their gut microbiota oxo-metabolites are the most specific steroid markers for detecting faecal inputs. This is due to their extreme chemical stability and their exclusive occurrence in vertebrate faeces, compared to other ubiquitous sterols and steroids.

Analysis of fecal bile acids and metabolites by high resolution mass spectrometry in farm animals and correlation with microbiota

“…Moreover, high fecal concentrations of several oxo bile acids (oxo-BAs) have been highlighted by HPLC–ESI–MS methods, specifically oxo-derivatives of the secondary BA deoxycholic acid (DCA). Indeed, such hixi-derivatives cover a significant fraction of fecal BAs, approximately 30% of the total pool 9 , 10 .…”

“…in archaeological studies on coprolites). In fact, thanks to their high stability and specificity, BAs and oxo-BA metabolites are promising biomarkers for the identification of human fecal inputs, giving a significant contribution to the growing field of bioarchaeology 10 .…”

The Technological Advance and Application of Coprolite Analysis

“…The steroidal biomarker analysis of a 14,000 years old putative human coprolite from Paisley Cave, which yielded the predominant presence of 5β-stigmastanol, and therefore reversely supported that the putative human coprolite was from a herbivore, and the presence of palaeoindian mitochondrial DNA in coprolites was inferred to be contamination (Sistiaga et al, 2014a). Beyond that, bile acids, testosterone, and estrogen levels also help to identify the producers (Rhode, 2003;Zhang et al, 2020;Porru et al, 2021).…”

Improvement of soil fertility in historical ridge and furrow cultivation

“…Furthermore, the correlation of phosphate and bile acid contents strongly suggested soil amelioration by application of livestock waste at some sites. Bile acids are the best indicator because they are resistant to weathering and “absent in plants and invertebrates, which makes them more appropriate than stanols and stanones for characterizing the origin of fecal input” (Porru et al, 2021). At A‐RAT and A‐KLÖ sites, increased amounts of some bile acids—particularly DCA and HDCA, and to a lower extent LCA and CDCA—were detected in comparison to the reference profiles, although the values were comparably lower than in other steroid analyses (e.g., Prost et al, 2017; Zocatelli et al, 2017).…”