Steroid Biomarkers Revisited – Improved Source Identification of Faecal Remains in Archaeological Soil Material

Abstract

Steroids are used as faecal markers in environmental and in archaeological studies, because they provide insights into ancient agricultural practices and the former presence of animals. Up to now, steroid analyses could only identify and distinguish between herbivore, pig, and human faecal matter and their residues in soils and sediments. We hypothesized that a finer differentiation between faeces of different livestock animals could be achieved when the analyses of several steroids is combined (Δ5-sterols, 5α-stanols, 5β-stanols, epi-5β-stanols, stanones, and bile acids). We therefore reviewed the existing literature on various faecal steroids from livestock and humans and analysed faeces from old livestock breed (cattle, horse, donkey, sheep, goat, goose, and pig) and humans. Additionally, we performed steroid analyses on soil material of four different archaeological periods (sites located in the Lower Rhine Basin, Western Germany, dating to the Linearbandkeramik, Urnfield Period / Bronze Age, Iron Age, Roman Age) with known or supposed faecal inputs. By means of already established and newly applied steroid ratios of the analysed faeces together with results from the literature, all considered livestock faeces, except sheep and cattle, could be distinguished on the basis of their steroid signatures. Most remarkably was the identification of horse faeces (via the ratio: epi-5β-stigmastanol: 5β-stigmastanol + epicoprostanol: coprostanol; together with the presence of chenodeoxycholic acid) and a successful differentiation between goat (with chenodeoxycholic acid) and sheep/cattle faeces (without chenodeoxycholic acid). The steroid analysis of archaeological soil material confirmed the supposed faecal inputs, even if these inputs had occurred several thousand years ago.

Characterization of ancient lipids in prehistoric organic residues: Chemical evidence of livestock‐pens in rock‐shelters since early neolithic to bronze age

“…This model was not able to classify M11.1 sample, however, this sample could be altered. In this way, the absence of COP or EpiCOP could be attributed to the transformation of one isomer to another due to time (diagenesis) and not to the absence of ruminant residues . Thus, the presence of either COP or EpiCOP is enough to use in Eq.…”

“…The extraction of these compounds from fecal samples has been commonly carried out using Soxhlet as extraction technique (24-36 h/sample) [19,[23][24][25]. However, alternative extraction techniques such as ultrasound-assisted solidliquid extraction (20-80 min) [26][27][28][29] or PLE [30,31] have been used to accelerate the extraction time and reduce the extraction solvent. Commonly, different mixtures of dichloromethane/methanol (DCM/MeOH = 1:1, 2:1, 3:1, or 9:1) and volumes (20-200 mL) [24,25,32,33] have been used for the total lipid extraction.…”

Fecal stanols show simultaneous flooding and seasonal precipitation change correlate with Cahokia’s population decline

“…Fecal stanols deposited in sediment provide evidence of trace human waste products, and are used as a proxy for measuring population change over time (15,19). Although other mammals, including dogs, donkeys, seals, horses, goats, and cattle, produce coprostanol, only sheep and pigs are known to generate sufficient quantities that could mask changes in human stanol concentration (20)(21)(22)(23), and neither domesticate was present in the Cahokia area before Euroamerican settlement (24). White et al (15) demonstrated the validity of this approach by producing a 1,200-y record of Cahokia region population change through fecal stanol analysis of Horseshoe Lake sediment that parallels population trends identified by previous demographic reconstructions derived from archaeological evidence (2,14).…”

Opportunities and limitations related to the application of plant-derived lipid molecular proxies in soil science

“…A general trend of preferential preservation in smaller size fractions, in particular the clay fraction, is also reported in other studies. For instance, Quenea et al (2004) and observed longer turnover rates of SOM in smaller size fractions. Clemente et al (2011) studied the preservation of long-chain aliphatic compounds in three soils with similar clay mineralogy but different carbon contents and standing vegetation.…”

“…However, Otto and Simpson (2006) found the degradation of cutin and suberin to take place without preference for specific constituents. In general, Quenea et al (2004) described cutin and suberin to be more resistant to degradation than free lipids residing in the same particle size fraction.…”