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Experimental Archaeology in Food Residues

Published on August 27, 2020, a year-long experimental archaeology project led by Melanie Miller, Helen Whelton and Jillian Swift, examined food residues left in ceramic pots. Researchers recorded visible and absorbed residues left in pots in carefully controlled tests, supporting decades of research into evidence of culinary behaviors of the ancient past. This Background Check highlights the study of organic residue analysis and why this study is downright exciting.
La Chamba pottery used in the experiments
La Chamba pottery used over the course of the year-long study, taken at the conclusion of the experiment. Residues are visible on the inner surfaces and pots marked near the handles with the initials of each archaeologist-chef. Credit: Jillian Swift

Food Residues

The study of macro- and microscopic residues of plant and animal foodstuffs left inside of pots (as well as on grinding stones and stone tool edges) and known as organic residue analysis (ORA), has its roots in analytical chemistry studies of the mid-twentieth century. Today, organic food residues have been found in ancient ceramic containers as visible carbonized food crusts, as calcified deposits or thin patinas on the surface, or as invisible absorbed fats and oils (lipids) into the vessel walls. While crusts and patinas are fairly rare, Richard Evershed (2008) has estimated that absorbed organic residues survive in more than 80% of domestic cooking vessels worldwide.

In ORA, these residues are examined and chemically analyzed to identify component parts. Working with chemists, archaeologists have been able to identify terrestrial animal fats, aquatic fats from fish, shellfish, and marine mammals, plant oils and waxes, cereals, beeswax, resins, tars, and bitumen. That, in turn, leads to information about ancient diets.

But an ongoing issue has been figuring out what the observed residues tell us about the behavior that created them. Ethnographic studies—that is to say, studies of the culinary remains from indigenous chefs—have been conducted, but those are specific to the chef. What Evershed argued for in 2008, the team (with input from Evershed and ethnobotanist Christine Hasdorf) published on August 27, 2020, in Nature's open-source journal Scientific Reports.

Experimental Archaeology

Experimental archaeology is when archaeologists recreate presumed behaviors in a controlled situation, using reconstructed tools, recording the steps, and measuring the results. Those tangible results are then compared with ethnographic and archaeological examples, with any luck providing insight into ancient behaviors.

In the new paper, bioarchaeologist Melanie Miller and colleagues spent a year conducting weekly cooking episodes of different specific recipes of wheat, maize, and deer meat. For 50 weeks, each of seven cooking pots was used to make one recipe; in the last two weeks, they altered recipes. They used La Chamba crocks, a style of highly burnished pots made by a small indigenously owned-and-operated firm in Colombia. These pots are made by methods used since the pre-Hispanic period.

Results

Researchers looked at the residues for carbon and nitrogen stable isotope values in the food crusts and patina and lipid biomarkers in the vessel walls. Details of the experiment and results are presented online (Miller et al 2020), but in general, Miller and colleagues found that the isotope values of the food crusts generally reflect the last dish cooked in the vessel. The isotope values of the patina residues were slower to change, reflecting both earlier and later recipes; and the lipids are replaced very slowly and reflect an amalgam of the entire history of the pots' use.

Coda

This is an exciting discovery in general because it explains and contextualizes differences between the three measures (crusts, patina, and lipids). Researchers can now make some fairly reliable theories as to the life history of a cooking pot.

The report didn't include analysis of the occurrence of pollen, starches, or opal phytoliths, all of which would lend additional support to culinary archaeology that can be used to identify specific types of foodstuffs. Maybe that's in a forthcoming paper, but inquiring minds crave to know.

Selected Sources and Further Reading

Created by KKris. Last Modification: Thursday 27 of August, 2020 12:33:28 EDT by KKris.