Date Published: February 7, 2019
Publisher: Public Library of Science
Author(s): Loïc Harrault, Karen Milek, Emilie Jardé, Laurent Jeanneau, Morgane Derrien, David G. Anderson, Juan J. Loor.
Identifying the presence of animals based on faecal deposits in modern and ancient environments is of primary importance to archaeologists, ecologists, forensic scientists, and watershed managers, but it has proven difficult to distinguish faecal material to the species level. Until now, four 5β-stanols have been deployed as faecal biomarkers to distinguish between omnivores and herbivores, but they cannot distinguish between species. Here we present a database of faecal signatures from ten omnivore and herbivore species based on eleven 5β-stanol compounds, which enables us to distinguish for the first time the faecal signatures of a wide range of animals. We validated this fingerprinting method by testing it on modern and ancient soil samples containing known faecal inputs and successfully distinguished the signatures of different omnivores and herbivores.
The signatures of animals in the environment, or on an archaeological site, can be detected by the faecal material they leave behind. Archaeologists, forensic scientists, ecologists, watershed managers and others make use of the organic residues derived from faecal inputs in the environment to determine the presence of animals and/or human activities [1–10] or to pinpoint whether animal faeces were a source of organic nutrients (e.g. in arable soils, [11–18]) or pollutants in catchment basins (e.g. a source of pathogenic bacteria, viruses and protozoa, [19–31]).
Our results call into question the validity of using simple ratios and even multivariate statistics based on only four 5β-stanols for species-specific faecal fingerprinting. The faecal fingerprint reference library used here, and the use of PCA and HCPC models built using eleven 5β-stanols, provide much more precise faecal source attributions. The fingerprinting method employed here overcomes the limitations of using simple ratios involving only four 5β-stanol compounds (coprostanol and epicoprostanol, 24-ethylcoprostanol and 24-ethylepicoprostanol) to determine the main sources of faecal inputs in environmental and archaeological samples. For the two cases studied here, the model used confirmed the past presence of horses and reindeer on the Sai͡an Mountains site and reindeer and dogs on the I͡Amal peninsula archaeological site.