Maya Ground Stone Analysis

Project Archaeologist: Lisa Duffy

Ground stone tools represent the physical remains of food processing activities by the ancient Maya.  As such, they are an important part of the archaeological record that can contribute much to understanding past lifeways.  These grinding implements were used to process food items such as corn (maize) and cacao, as well as other plants used for spices such as chili peppers.  Medicinal and ritual herbs, as well as non-food items such as pigments could also be processed by these types of grinding tools.

These manos (handstones) and metates (platform or slab stones) come in different shapes and sizes, based on their intended function.  To determine the specific uses of these tools, different methods can be utilized to see which may have been used for general or mutli-purpose food grinding versus those that were used for specific products.

Whether the surface of the metate shows a reciprocal, back-and-forth grinding motion versus a circular, rotary grinding motion reflects the method employed by the user.  Reciprocal-motion is associated with a flat surfaced metate and a two-handed mano.  This is the most efficient method for processing food such as maize kernels and cacao beans. Rotary motion is associated with concave or bowl shaped metates or molcajetes and one-handed manos. These are often associated with dried foods, seeds, herbs and spices.

Residues of plants such as maize and squash can sometimes be recovered from the surfaces of stone grinding tools.  Starch grains and phytoliths can be collected by washing and then identified by microscopic analysis.

Plants and animals that were processed by these tools can also leave chemical traces behind.  Biomarkers of plants such as chili peppers or cacao can be discovered by mass spectrometry, and lipid analysis can show the presence of animal fats such as cholesterol or other plant-based compounds and waxes.

By using some or all of these methods, manos and metates can yield their secrets and contribute to our understanding of ancient Maya cuisine, environmental resources, food processing and tool function.

Sites included in this research include:

Ground stone fragments from Kante’t’u’ul, Peten, Guatemala. Photo by Lisa Duffy.
Ground stone fragments from Kante’t’u’ul, Peten, Guatemala. Photo by Lisa Duffy.
Fragment of 2-handed mano from Marco Gonzalez, Ambergris Caye, Belize. Photo by Lisa Duffy.
Fragment of 2-handed mano from Marco Gonzalez, Ambergris Caye, Belize. Photo by Lisa Duffy.











Report on Progress: Ground Stone Analysis

Chemical residues and starch grains have been successfully recovered from ground stone manos and metates from seven ancient Maya sites; Cerro Maya (Cerros), Lamanai, and Marco Gonzalez in northern Belize, and four sites in the Motul Polity in the Peten region of Guatemala. These residues include theobromine, caffeine, and theophylline (cacao), nicotine and cotinine (tobacco), capsaicin (chili pepper), vanillin (possibly from vanilla), as well as a variety of aromatic compounds found in herbs and spices such as camphor, sulcatol, pulegone, and trans-cinnamaldehyde. Starch grains recovered include maize and chili pepper, and also grains that show damage consistent with processing techniques such as grinding, heating/cooking, and possibly fermentation.

cluster of starch grains from metate
Cluster of starch grains from metate SF 0104 from Cerro Maya
starch grains under polarized light with "extinction cross"
Same starch cluster under cross-polarized light showing the “extinction cross” pattern diagnostic for starch grains.