By Venicia Slotten
This July, supported by a Tinker Foundation and CLAS-funded research grant, I helped excavate a house structure in Costa Rica that was preserved by the eruption of Arenal Volcano around 3,500 years ago. This archaeological site, La Chiripa, is one of the oldest known domestic structures found to date in Central America. The ancient house was discovered in 2016 by the Proyecto Prehistorico Arenal, directed by Payson Sheets and Christine Dixon. The recovery of ancient botanical remains here provides an excellent opportunity to address questions regarding the daily lives and resilience of ancient people in this region of the world. La Chiripa’s landscape has been continually inhabited for approximately 2,500 years, persevering through frequent volcanic activity. Distinct ash deposits help distinguish between periods of human occupation, with abandonments, ecological recovery, and reoccupations after each eruption. The research will provide invaluable information regarding ancient household practices, long-term residence stability, and environmental resilience in pre-Hispanic Central America.
As a paleoethnobotanist, my role was to collect soil samples from the floor surface of the house structure and also from each cultural strata covering this remarkable find. Extra samples were taken from any cultural features we encountered during excavations as well, such as post-holes from where the house was once anchored or darkened organic features that could have been a hearth or cooking pit. Once processed and analyzed, these soil samples will help researchers know the assemblage of food the ancient inhabitants of the house were consuming and other details about the environment that surrounded their home. Soil samples designated for water flotation were taken to recover the larger macrobotanical remains such as seeds and wood charcoal that can be identified later based on their morphological and anatomical characteristics. Separate samples were also taken that were designated for phytolith and pollen analysis, to provide a more microbotanical view of the ancient flora.
All botanical samples were then exported back to the UC Berkeley McCown Archaeobotany Laboratory for analysis. Employing a variety of collection techniques will help my project determine which methodology is more productive in future excavations while also maximizing what was collected in 2018. Operation of the flotation device and collection of materials is labor intensive and requires assistance, so it was an excellent opportunity to train a local Costa Rican archaeologist who can now aid in the recovery and processing of the botanical data elsewhere on other archaeological projects in their country. Processing archaeological samples using water flotation is not yet widely practiced in this region of the world, so there is still much to learn about past foodways of Central America. Paleoethnobotanical recovery can speak to various aspects of daily household practices: This analysis can reveal information regarding how plants in the past were utilized as food, medicine, fuel, tools, clothing, construction material, and even art. The botanical results will be combined with research from other members of the archeological team, who focus on lithic, ceramic, organic residue, and spatial analyses. All of this information will be combined and work together to depict the past lives of pre-Hispanic Central Americans.
The analysis of the paleoethnobotanical samples is a long process that I will undertake here at Berkeley for the next several years, as it involves hours of microscope work and identification of plant material. The experience of collecting these botanical samples showed me just how much there is to learn archaeologically in this region. Few researchers have collected these types of macrobotanical samples in Central America, often claiming that there just is not enough preservation of organic remains to make the recovery efforts worthwhile. While this particular site does have exceptional preservation due to nearby volcanic activity, the project also suggests that other efforts elsewhere in the region to recover macrobotanical remains could prove to be productive as well. I hope that my interactions with other scholars during my time in Costa Rica demonstrated that this field of study could yield fantastic results; it is just a matter of taking the time and energy to collect the samples.
Initial results of the floated soil samples show abundant carbonized organic matter was collected. The next step is to sort and identify the assemblage of plant remains that were preserved for thousands of years to tell us a story about the past lifeways of Central America!
Venicia Slotten is a PhD student in Anthropology at UC Berkeley. Venicia earned her MA in Anthropology from the University of Cincinnati and a BA in Anthropology and Latin American Studies from Miami University. Her main research interests include household archaeology, paleoethnobotany, historical ecology, and Latin America.