Mon. Sep 26th, 2022
Two rows of simple black pots.
enlarge Seven unglazed ceramic pots from La Chamba were used in a one-year cooking experiment that analyzed the chemical residues of the prepared meals.

Archaeologists are fascinated by many different aspects of cultures in the distant past, but determining what ancient people cooked and ate can be especially challenging. A team of researchers spent an entire year analyzing the chemical residues of some 50 meals cooked in ceramic pots and found that such cookware contained not only the remains of the last meal cooked, but also clues to past meals, which cover the entire life of a pot. This could give archaeologists a new tool in determining ancient diets. The researchers described their results in a recent article published in the journal Scientific Reports.

According to co-author Christine Hastorf, an archaeologist at the University of California, Berkeley (UCB), the project has been in the works for several years. Hastorf has long been interested in the relationships between humans and plants throughout history, especially as they relate to what people ate in the past. In 1985, she co-authored a paper examining the isotopes of charred plant debris collected from the insides of pots. She has also long taught food archeology at UCB. A few years ago, she extended the course to two full semesters (nine months), covering both the ethnographic aspects and the archaeological methods you could use to gain insight into past food habits.

The class was particularly intrigued by recent molecular analysis of pottery, but frustrated by the brevity of the studies done on the subject to date. Hastorf suggested doing a longer study, and her students responded enthusiastically. So they devised a methodology, gave research topics to each student and located places to buy grain (corn and wheat from the same region of the Midwest), and received venison in the form of donated deer. She even bought her own mill so they could grind the grains themselves, and set it up in the garage of her house.

A La Chamba ceramic pot in use during the experiment.
enlarge A La Chamba ceramic pot in use during the experiment.

For the pots, they chose newly purchased unglazed La Chamba ceramic pots – robust black clay cookware whose use dates back to pre-Columbian South America. Each student was given a homemade stir stick plucked from the apple tree in Hastorf’s backyard to clean the pots after each meal. Then they all started cooking.

“We cooked for a year — once a week for 52 weeks,” Hastorf told Ars. Every eight weeks, they burned the meal and took samples of that charred residue for analysis, as well as the charred patina that formed over time. For the analysis of the fatty lipids incorporated into the clay cookware, they collaborated with Richard Evershed’s lab at the University of Bristol in England. Evershed is a master at studying the organic residues in ceramics: dairy products and meat in particular. However, until Hastorf contacted him, he hadn’t focused on plant material – another key addition this project has brought to the field.

Admittedly, Hastorf and her team didn’t use “recipes” in the modern sense of the word. The “meals” consisted of just three ingredients in six different combinations: corn, ground wheat, and game, plus a little water. They did have some recipes where the corn was made into a hominy by adding lime extract. “It was a goopy thing on the stovetop, and it wasn’t tasty,” Hastorf said of their creations. “We never thought of putting it in our mouths. That wasn’t part of the equation of this science experiment.”

Residue in a La Chamba pot after cooking a meal.
enlarge Residue in a La Chamba pot after cooking a meal.

The idea was to control the number of variables for a more rigorous experiment. “We wanted to keep it simple and control the molecules,” Hastorf says. “You start adding salt and you change everything. And we wanted to keep it diagnostic. We chose the food based on how easy it would be to distinguish the chemicals in the food and how the jars would react to the isotropic and chemical values ​​of the food.The bottom line is that corn is a C4 plant and wheat is a C3 plant so they will go a very different pattern [in the isotope analysis]†

They found that the charred bits at the bottom of the jars were evidence of the last meal cooked. But the patinas contain traces of the remains of previous meals that had accumulated over time. So it depends on which part of the pot you taste.

“We can study a range of plants and animals from that region and begin to reconstruct both what cooked the pot during its life, but also what its last meal was, because we know that the last charred crust is pretty much the remains of the last meal cooked in that pot,” Hastorf said of the findings. “What was new was that over time we cooked for so long, and you could see the variability in those pots. So we can say, ‘Yeah, this pot really only cooked corn. They didn’t cook beans in pot here. .'”

“Our data could help us better reconstruct the meals and specific ingredients people consumed in the past, which in turn could shed light on social, political and environmental relationships within ancient communities,” said study co-author Melanie Miller, now a researcher. postdoctoral researcher at the University of Otago in New Zealand: “We have opened the door for others to take this experiment to the next level and establish even longer timelines in which food remains can be identified.”

DOI: Scientific Reports, 2020. 10.1038/s41598-020-70109-8 (About DOIs).

By akfire1

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