Cherries Galore in a Cesspit

By Merit Hondelink

As an archaeobotanist, an archaeologist specialised in studying plant remains found in archaeological excavations, I aim to reconstruct and interpret the relationships between humans and plants in the past. Archaeological plant remains, also known as subfossil plant remains, help us to reconstruct the former landscape and inform us how humans exploited it and even transformed the vegetation. Archaeobotanists do not necessarily study one time period, nor a specific region or topic. They can study plant remains from the Palaeolithic or the 20th century, and everything in between. They can focus on one specific site, work across the country or continent, and even work worldwide. They can delve into topics such as natural vegetation, forestation, domestication, trade, food consumption and much more. The one thing that all of this has in common is the link between humans and plants. But most archaeobotanists do specialize, most notably in the plant parts they study, such as fruits, seeds, pollen, wood or phytoliths. And most archaeobotanists have a beloved time period, favourite region or topic that they find most intriguing. In my case my research focuses on early modern Dutch urban food consumption.

I study what people ate in early modern Dutch cities, and how this changed through time. The best way to study what people ate in the past, is to look at their excrement and kitchen refuse, both of which can be found in the archaeologists treasure trove: the cesspit. These latrines were used to empty one’s bowels, but also served as a place to discard kitchen refuse and household waste. The content of a cesspit consists of organic remains from plants and animals, inorganic (culinary) material culture such as earthenware, glassware and ceramics, but also wooden cups and plates, as well as (decorative) objects, personal belongings and much, much more.

Figure 1: A selection of faunal and floral items found in a late medieval cesspit sample from Groningen. Photo: Dirk Fennema.

The content of an archaeobotanical cesspit sample consists of, among others, floral remains in different shapes and sizes (Figure 1). The items are sorted with the use of a microscope (Figure 2) and identified on a species level (and sometimes even on the level of species variety) by using a reference collection (Figure 3). The Groningen Institute of Archaeology offers a wonderful digital, open access, reference collection, see

Figure 2: A peek through the microscope. Visible is a fragment of text and different seeds and fruits, taken from an early modern Delft cesspit sample. Photo: Merit Hondelink.

When the content of a cesspit sample is analysed, sorted and identified, the interpretation begins. What can these plant remains tell us about past human-plant relationships? Most plant species are interpreted in a standardized way: wild plants inform us about the vegetation composition, make-up of soils and hydrology, whilst agricultural weeds in particular inform us about the crops grown and their local, regional, international or even global provenance. Wild but poisonous or toxic plants inform us about potential medicinal applications. A majority of plant species found in cesspits are classified as economic plants, grown as a food crop or cultivated for other useful purposes, such as fibres for textiles or seeds for oil. Identifying edible plants helps us better understand what plants people used for food and which parts people consumed. It also helps us better understand how food was prepared in the past, as preparation marks can be left behind on seeds and fruits.

Some preparation marks are easier to identify than others: nuts need to be cracked to get to the seed; apple seeds may be sliced when cutting up an apple, cereals can be ground, resulting into fragmented bran. But sometimes the archaeobotanist finds fragmented plant parts that, at a first glance, do not make sense.

Figure 3: A small selection of the tubes from the archaeobotany reference collection housed at the Groningen Institute of Archaeology (GIA) at the University of Groningen. Photo via GIA.

I have come across dozens and sometimes hundreds (or even more) cherry stones and plum stones in a single cesspit sample. No surprise there, cherries and plums were grown in local orchards, sold in the market and consumed with gusto. Most of these stones will have been discarded in the cesspit as a result from eating the fruits and spitting out the stones, or after de-pitting the fruits for dinner preparation. Only a small percentage is assumed to have been accidentally swallowed and secreted as excrement. Still, archaeobotanists find many fragments of cherry and plum stones (Figure 4). This is something that raises questions when you think about it. Why would these sturdy fruit stones be fragmented? A more pressing question when you are aware that the Rosaceae family, among others also including almond, peach, and even apple, contains – to varying degrees – hydrocyanic acid, also known as hydrogen cyanide and sometimes called prussic acid. The seed coat and fruit wall protects the consumer from digesting this acid, which can be poisonous when consumed. So why would someone break the stones of these fruits?

Figure 4: Two fragments of cherry stones found in an early modern cesspit in Vlissingen. Photo: Merit Hondelink.

To test the assumption that cherry stones were fragmented intentionally, and not through, for instance, pressure, an experiment was devised. Cherries were bought at the farmer’s market and taken to a physics lab to measure the pressure required to fragment the stones. After a number of tests, the calculated force to fragment a cherry stone averaged 23,9 kg or 239 Newton (Graph 1). This makes it more plausible that the stones were intentionally fragmented, as opposed to – for instance – fragmentation due to soil pressure.

Graph 1: Force needed to fragment a cherry stone. On the vertical axis the force (N), on the horizontal axis the elongation (μm). The point where the line falls is the moment the cherry stone breaks (max. force – max. elongation).

Consulting early modern cookbooks provided me with a list of recipes requiring the cook to de-stone cherries for the preparation of jams, sauces, syrups and tarts. Delicious experiments ensued, but I did not manage to fragment cherry stones whilst cutting and de-stoning, pressing through a cloth or colander, or by just baking the fruit with stones in a tart in the oven. Working a batch of cherries with a mortar and pestle did the job, though. But than you would have to pick the fragmented stones from the mushy cherries: not ideal at all. Picking up the eighteenth century encyclopaedia compiled by Noël Chomel gave me the hint I needed. In the Dutch version of his Dictionnaire œconomique (Algemeen huishoudelijk-, natuur-, zedekundig- en konst- woordenboek), he mentions different recipes for preparing cherries. Two recipes for cherry liquor instruct the reader to fragment the cherry stones by using a mortar and pestle (Figure 5). The fragmented fruits, including the stones and (I assume) the seeds are added to the brandy (Dutch: brandewijn) and, after closing the bottle, the mixture is put in the sun to infuse. Adding spices such as cinnamon, cloves and sugar is optional, according to the author.

Figure 5: How to make a pleasant cherry liquor (Noël Chomel, 1778).

So, it is plausible that the fragmented cherry stones found in early modern cesspits are the result of the domestic production of cherry liquor. Other fruits, such as plums and peaches, are also used to make a fruity liquor according to Chomel’s encyclopedia. However, what happens to the acid contained in the seeds? That requires further research. It might be that the prescribed infusing in the sunlight helps denature the acid into harmless molecules, leaving only the (bitter) taste behind. This line of research will be undertaken come summer with the aid of a brewer and some chemical analysis. In the meantime, a cherry and cinnamon flavoured lemonade is my poison of choice. Bottoms up!

Conference Report: Materia Medica on the Move, Leiden, 15-17 April 2015

By Sietske Fransen

What happens if you put together historians of early modern science and medicine, ethnobotanists, historians of pharmacy, and art historians in the Dutch National Biodiversity Center in Leiden? Last month this resulted in an amazing conference where we discussed the (global) movements of early modern materia medica. The conference was jointly organized by the Descartes Centre (Utrecht University), Huygens ING, and Naturalis Biodiversity Centre.

The conference was hosted by the project Time Capsule and was interdisciplinary to its core. The project’s aims and goals are wonderful, and deserve some explanation, so here it comes. Project Time Capsule has as aims to create a ‘semantic interoperable ontology’ of cultural heritage data. This ontology will consist of a combination of existing digital databases and new data, in order to provide historians as well as the creative industry with new methods for research. And the actual ‘time capsules’ – based on Andy Warhol’s project – are supposed to contextualize historical events or facts. To exemplify this exciting but rather mystifying concept, Time Capsule works specifically on data sets related to the history of medicinal plants in the Low Countries, c. 1550-1850. With a team of computer scientists and historians of science the project tries to set an example for further research into the development of digital resources. The final goal is to enable scholars to connect, compare and use an enormous amount of digital resources regarding early modern material medica.

A re-created sunflower, using real sunflower leaves in a herbarium of Felix Platter. Burgerbibliothek Bern, ES 70.6, fol. 155.
A re-created sunflower (native to the Americas), using real sunflower leaves in a herbarium of Felix Platter. Burgerbibliothek Bern, ES 70.6, f. 155.

The conference started at Museum Boerhaave with a key-note lecture by Florike Egmond, who  the introduction of non-European ‘medical’ plants into the European context. Even though there were not that many exotic plants actually introduced in European medicine in the sixteenth century, it is remarkable to see that they did gain a rather prominent present in visual sources such as herbaria, prints, and paintings. One of Egmond’s concluding questions and useful pointers for the rest of the conference was to wonder what ‘exotic’ or ‘indigenous’ really means. How long does a plant need to be grown in Europe to be no longer exotic?

The following two days took place at Naturalis Biodiversity Centre. One of the most exciting papers (at least to me) was given by ethnobotanist Tinde van Andel.

Materia Medica on the Move - Tinde van Andel
Key-note lecture by Tinde van Andel

Van Andel showed us how the movement of knowledge about local plants can be traced by following African slaves from their home countries to the Surinam rain forests. Combining ethnobotanical and anthropological field research in West-Africa and Surinam with historical botany and linguistics Van Andel argues that enslaved Africans reinvented their household medicine in the New World. Van Andel’s research demonstrates clearly how the knowledge of plants travelled with the people and was adapted to the needs of surviving on a new continent. Through trial and error and comparison with the knowledge they brought about African flora, the slaves figured out which new but similar plants could be used as medication and food. 

Historian of Pharmacy Sabine Anagnostou, used pharmacopeias in Europe and America to research the transfer of medicinal plants and drugs. She not only looks at the import of exotic plants into Europe, but also at the building and use of pharmacies in the New World. Jesuits were of major importance in the development of such institutions, and would use their own knowledge of European plants in combination with local knowledge in these New World settings. She argues, amongst other things, that there is still a higher amount of European plants present in the American pharmacopeias then the other way around.

Harold Cook delivered the final key note lecture about the ‘Atlantic drug trade and the new sciences’. Cook argued convincingly that we need to study the developments in the use of drugs at the large plantations in the Caribbean to explain the globalization as well as entrepreneurship that started to become connected with medicine from the eighteenth century onwards.

Harold Cook, key-note lecture.
Harold Cook, key-note lecture.

The owners of big plantations were looking for a universal medicine that would cure any disease, in any situation, in any person, with the best possible outcome. The idea behind this was to make sure that ill people could go back to working again as soon as possible. According to Cook the impersonality of these developments (from drugs aimed at an individual to drugs aimed at large groups of people) should be seen and studied (!) as major issues in the changing perception of social medicine in the 17th and 18th century.

Unfortunately this blog is too short to give a description of all papers, but a brief report of all presentations can be found here. The papers covered topics like botanical gardens in Leiden, Poland and Russia; testing of new and unfamiliar drugs in both European and Asian contexts; and the materiality and circulation of herbaria in Early modern Europe. Just as examples I would like to mention Alexandra Cook’s paper on the approval of exotica in a European medical context. She argued that both ginseng and tea (after they were brought to the West) were for a while seen as universal medicines. However, during the eighteenth century, these unproven claims were no longer seen as valid. This lead to reports based on observations and experience in which the qualities of the exotic drugs were systematically described. A last example comes from Davina Blankert, who showed us how the Swiss botanist Gaspard Bauhin and the Veronese apothecary Giovanni Pona discussed exotic plants in their correspondence. Blankert argues that the scholars utilization of plant names with few plant descriptions demonstrates that both were conversant in their knowledge of exotic plants using similar nomenclature and terminology. Bauhin would later publish his acquired knowledge about exotic plants in his famous book Pinax theatri botanici.

Gaspard Bauhin, Pinax theatri botanici, Basel 1623. Title page.
Gaspard Bauhin, Pinax theatri botanici, Basel 1623. Title page.

Bringing together so many different scholars, methods, used materials, and questions seems exactly the point of Warhol’s Time Capsule project. Fortunately for us, the focus of this specific project is not the daily life of Warhol but the ‘daily life’ of materia medica between 1550 and 1850. The conference gave a wonderful view into the research that can be done when material will be collected and brought together in digital form. The current scholars working on all these different aspects of materia medica will hopefully be the providers of the content as much as they should be able benefit from the integration of the all the existent cultural heritage data.