Phytoliths, paleoecology and plant foodways at El Flaco, northern Dominican Republic

Phytoliths are microscopic bodies that are formed in many plants when silica (in a dissolved state) is absorbed from the soil and then accumulates and solidifies within different intracellular and extracellular structures of the plant. These bodies are highly resistant to the inclement of time and weather and are useful to identify plant families and in some cases species. In the last decades, phytoliths studies have been more recurrent in archaeological projects to facilitate research on plant usage at different levels from household activities, to socio-ecological and landscape management practices. The aim of our phytolith study is to better understand the formation process and varied uses of the multi-functional mounds and kitchen areas already documented at El Flaco in order to complement other lines of research focused on ancient plant foodways.

How do we do it?

The analyzed samples come from one of the multi-functional mounds identified at El Flaco. These samples were collected from a soil core extracted by Dr. Pagán-Jiménez in January 2018 as part of the Nexus 1492 project. Soil samples were then packaged and sent to the Faculty of Archaeology at Leiden University to undergo laboratory processing and further analysis. Samples were submitted to a specialized protocol which included the chemical digestion of carbonates and organic matter, the chemical flotation of phytoliths, and the mounting of them for further microscope analyses. Next, phytoliths were counted and identified to different taxonomic levels with an optical microscope, following morphometrical criteria based on a comparative collection of neotropical plants. Then, the quantified results were used to produce paleoecological graphs and preliminary interpretation.

What are we looking for?

Among other things, phytoliths allow us to understand issues of plant/forest succession and how ancient humans affected these processes. Broadly speaking, forest succession refers to how and when different plants are involved in the varied steps toward the vegetal colonization of an area. In this sense, humans intervene on forest structure and succession when they integrate or pay special care to some useful plants, or when they apply different forest management practices to create their living spaces and their horticultural plots. In this context, the distribution, reproduction, dispersal and/or eradication of plants is affected by humans, thus modifying the original forest structure of which microbotanical traces (such as phytoliths) remains after a long time. Therefore, when comparing how identified ancient plants interact and behave before, during, and after the arrival of humans to the studied site, it is possible to interpret underlying socio-ecological processes to gain new insights on forest management practices and plant foodways by the indigenous communities at El Flaco. Other aspects such as past climatic conditions and particular climatic stress events can also be inferred by means of phytoliths analysis.

Preliminary results

Preliminary results have revealed that a complex dynamic existed between ancient human activities and ecological aspects. Our approach helps to better understand the local and regional forest, as well as forest management practices and climatic events before, during, and after human occupation of El Flaco. The studied multi-functional mound was a place in which natural and anthropogenic processes and activities collided. Plants from the surrounding environment were naturally integrated into the mound through time, together with other economic plant byproducts that were intentionally deposited there. This set the stage for studying the contingent nature of these kinds of archaeological features. Results obtained from the studied mound will then be compared with results from other mounds and site features (hearths) of El Flaco, in order to produce high-resolution interpretations of the use of spaces for plant processing, cooking, and disposal at the site and on a regional level.

by Carlos G. Santiago-Marrero