The Energy of Plants

Starches are polysaccharides in which plants store their energy, and they can be found somewhat abundantly in the archaeological record – on shell tools, stone tools, in dental calculus, on ceramics and so on. Starches can also be quite resilient and have been found at archaeological sites around the world dating to be over a million years old. Starch grain analysis of ancient human dental calculus can indicate what types of starchy plants were consumed, and this information can add to an understanding of the paleodiet and agricultural practices, among other things, of the studied populations, as well as enable spatial and temporal comparative analyses of past foodways. However, due to the chemical degradation of starches by oral secretions (e.g., amylase) during life, it is typical for dental calculus to contain less starch grains than other types of samples.

Starches of Trinidad

Starches have been studied in paleoethnobotany in the Caribbean since the early 2000’s. In Trinidad, starch grain analysis on human dental calculus has been done from the Manzanilla site in southern Trinidad (Mickleburgh and Pagán-Jiménez, 2012). Starch analysis  on stone tools from the St. John site by Pagán Jiménez and colleagues (2015) resulted in the identification of the oldest known domesticated and wild food crops (such as maize, sweet potato, wild yam, and chili pepper) in the insular Caribbean and northeastern South America.

The dental calculus samples currently being examined are from the Red House site, Port-of-Spain, Trinidad. This is a multi-period site with a range of finds including pre-colonial and colonial biofacts and artefacts. The calculus samples are from Saladoid and Arauqinoid (Guayabitoid) burials, and the individuals are of varying ages and sex.

Processes of Analysis

Generally, analysis of microbotanical remains is a time-consuming endeavor and requires meticulous caution from the analysts at all stages (from the site to microscope) in order to prevent damage to and contamination of the samples. Processing the samples involved cleaning the teeth with an ultrasound device, chemical degradation of the carbonate solids that form the dental calculus, then several rounds of centrifugation with ultrapure water to clean the samples. Finally the remaining samples were mounted on slides for microscopic analysis. Using a polarising microscope, the slides are examined for starch grains, and photographs, measurements and taxonomic identifications of any starches found are made where possible.

Analysis of these samples is still ongoing, and therefore results are not conclusive. It is expected that the eventual results can add another dimension to the understanding of the dietary aspect of the buried individuals, in collaboration with other dietary investigations done at the site such as lipid residue analysis on ceramic sherds and faunal analysis. 

by Zara Ali