Researchers create a reference collection of cattle faeces for archaeological studies in Menorca

A study carried out by archaeologists in the island of Menorca materialises in the creation of a reference collection of faeces from bovine, ovine and porcine cattle. It will serve as a modern reference to contrast and study faeces rests found in archaeological excavations.

Pigs in one of the agricultural estates of Menorca. Autumn 2018.Fossilised excrements from animals and other microscopic indicators are among the different organic and inorganic rests that archaeologists can find in excavations. These indicators can not only give us information about life in a particular place from the past, but also data about the origins of stockbreeding and the processes of domestication. These rests can give answers to questions such as, what these animals ate, what species of plants or parts of plants do these vegetal rests found in the faeces belong to, or if animals suffered from a certain disease. Moreover, they can also help clarifying the diversity of agricultural and livestock practices and their ecological impact.

However, excrements found in archaeological sites are not generally identified and their study requires reference material to compare it with. The project leaded by Marta Portillo helps in filling this existing gap in research. Portillo is currently a distinguished researcher at the Institución Milá y Fontanals of Humanities Research (IMF-CSIC, by its Spanish acronym).

Portillo, who made the analytical part of the project at the Universitat Autònoma de Barcelona alongside the palynologist Yolanda Llergo, presented the first scientific results of the study at the University of Reading (UK) in 2020, already as a member of the IMF-CSIC. Portillo and her team prepared between 2018 and 2019 a new modern reference collection with bovine, ovine and porcine faeces from three agricultural estates of Mahon (Menorca, Balearic Islands).The innovative aspects of the project are the gathering of faeces’ samples during the four different seasons for a microscopic analysis of their contents, and the introduction of the pig, that could not be studied in their earlier projects in Tunisia, Syria and the Kurdistan Region (project that was funded by the EU MICROARCHAEODUNG).

Bioarchaeologists always base their work on previous reference collections of the studied material, so this project’s purpose is to offer a modern reference with which to contrast and study the rests of faeces from archaeological excavations.

Sampling, analysing, comparing and contrasting

Marta Portillo explains, “We carried out the sampling of modern dung during different seasons through a study of vegetal and faecal microrests, mostly pollen and other microparticles such as fungal spores, in order to understand changes in livestock management and in animals’ diets.” The researcher adds: “We studied phytoliths found in faeces (microfossils that reproduce plants cellular structure) and also faecal spherulites, calcitic microrests that are produced in animals’ digestive systems, especially in herbivores.”

Even though the samples are all of present excrements, faecal indicators with antiquities between 3000 and 2000 years have been found in the talaiotic Menorca, which is candidate to UNESCO World Heritage Site. For example, faecal microrests were found in ashes, which might suggest that the faeces were used as fuel. In fact, this application can be found in other contemporary cultures of the Mediterranean and it is a practice that even today is observed in rural settlements.

Fieldwork results are useful for comparing today’s faecal rests with that of ancient times. Although direct analogies with nowadays societies and cultures are to be avoided. This research also allows to explain how livestock management was carried out in the past, at the same time that it gives information about the type of nutrition they had, seasonality (thanks to indicators such as pollen seeds and other microrests) and the different usages that excrements have had. Apart from being a ground and vegetable garden fertiliser, this material is key as an energy source for some contemporary societies.

Information obtained through microscopic study of livestock’s faeces is also valuable in regards to environment and energy sustainability.

Special settlement in Menorca

Menorca has a rich heritage and rural landscape and UNESCO designated it as a Biosphere Reserve in 1993. The three agricultural estates of Mahon selected for the study (Algendaret Nou, Talatí de Dalt y Es Capell de Ferro) are in an ideal place, explains the researcher, as they have important talaiotic settlements and they are close to a meteorological station. This helps in easily controlling precipitations in the area of study and in the places were the locally growncrops are used as fodder.

Teapot heated with excrements. Kurdistan Region, 2017.These settlements were also chosen because of the livestock that can be found there: cows, goats, sheep and pigs. All of these animals have been very important to the Mediterranean areas since their domestication. Therefore, it is expected that results can be useful for the study of other ecosystems of the Mediterranean flora and other historical time periods.

The researcher also explains that the estates’surroundings “provided us with the interesting possibility of observing these animals in semi-liberty, which made possible to identify indicators of seasonality in their diet.”

Portillo highlights the importance that for this study has had working alongside the owners of the estates and their families, from whom they have learned a great deal. They have opened their homes to show them the working methods of their farming activity and the traditional methods that they still use today.

The project is funded by the Consell Insular de Menorca. One of the institutions’ goals is the safeguard and promotion of historical heritage. This project is part of the grants that the Consell Insular awards to historical, archaeological and palaeontologist researches.

Marta Portillo presented the results of “Microarchaeology of dung through experimental archaeology” as an invited conference speaker at the Museo de Menorca. The meeting counted with the attendance of some of the local producers, demonstrating their interest and social compromise with archaeological research, as well as their rich ecological and rural heritage. The scientific results will be published shortly and her team is now on the process of receiving further projects for the same location of study.

Alongside Marta Portillo as the main researcher, other members of the team comprise Damià Ramis and Montserrat Anglada, both from Museo de Menorca, and Yolanda Llergo through a contract with the Universitat Autònoma de Barcelona. Other collaborators have been Antoni Ferrer from Institut Menorquí d’Estudis and Kate Dudgeon from the Archaeology Department of the University of Reading (UK).

Lydia Gallego Barco / Communication Department DICAT-CSIC