When it comes to kitchen utensils, there's nothing better than olive oil. It can do it all: spice up a salad, sauté vegetables, add crispness to noodles, and much more. Humanity has used olive oil for about 8000 yearsSo archaeologists Olive oil residues on excavated pottery are often reported.
However, in some regions the prevalence of this miracle food may have been exaggerated. For decades, archaeologists may have misidentified olive oil in Mediterranean pottery, perhaps missing other vegetable oils or mistaking olive oil for animal fat. The reason for this potential archaeological shake-up? new study published in Journal of Archaeological Science shows that organic residues of vegetable oils are poorly preserved in calcium-rich Mediterranean soils. So what archaeologists previously thought were olive oil residues on pottery could have been the result of some other food source.
“I wash the dirty dishes”
Technically, the interdisciplinary study began in 2019. As a doctoral student, co-author of the study, and archaeologist at Cornell University. Rebecca Gerdes also studied chemistry and wanted to better understand how it could be applied to archaeology.
“I usually describe my job this way: I wash ancient dirty dishes, save the rinse liquid, and use the molecules in it to figure out how people use their pans,” Gerdes the statement says.
Organic residue analysiswhere archaeologists and chemists join forces to study the molecular composition of plant and animal remains at an excavation site, is already an established discipline of archaeology. However, many old claims about the presence of olive oil in ancient places have never been revised. technology The situation has improved, so some pots and pans dug up many years ago may not have olive oil at all.
On the recommendation of her Ph.D. Sturt Manning chairman Gerdes decided to dig deeper.
“One of the things I realized early on in my PhD was that people were making all sorts of claims about what they found in pots in the eastern Mediterranean, and there was a lot of opportunity to back up those claims with more serious experiments,” she said. “I wanted to answer some interesting archaeological questions, but realized I needed to “develop a ‘method’ to do it.”
Gerdes collaborated with other Cornell researchers, finding a key partner in chemical engineer Gillian Goldfarb.
Ancient Play-Doh
Due to travel restrictions in… early days of the COVID-19 pandemicGerdes was unable to travel to assess the geological conditions of Cyprus, island country in the eastern Mediterranean Sea this was her area of focus in this study. Instead, she received samples of Cypriot soil from the Cornell Soil Health Laboratory. There, scientists sterilized the samples before handing them over to Gerdes' team for safe study. Soil Health Lab Director Bob Schindelbeck also played a critical role in helping Gerdes understand how these soils behave.
Together with Goldfarb's biochemical research group, Gerdes developed laboratory experiment to test how the soil's unique chemistry triggers chemical reactions that break down food debris found on ancient pottery. They created ceramic granules using rolled terracotta clay and fired them in a tube kiln.
“I kept thinking about playing with Play-Doh,” Gerdes said.
Thilo Reren of the Cyprus Institute collected samples of Cypriot soil and sent them to upstate New York. Then they soaked the granules in olive oil and buried them in two types of moist soil. One of the soil samples was from Cyprus and the other was from the Soil Health Laboratory's agricultural fields, which are less acidic.
Cyprus “the soil is really common in the eastern Mediterranean, so it influences a lot of important historical periods, especially when we look at trade and connections in that region,” Gerdes said. “Late Bronze Age. [about 1650 to 1100 BCE] is one of those periods of time.”
For a year, samples were stored in incubators at temperatures up to 122 degrees Fahrenheit (50 degrees Celsius). The team then dug up the granules and recovered the remaining olive oil. In the laboratory, they studied the profile of molecules preserved on the granules.
“We were able to do this in the lab at an accelerated pace, so we didn’t have to wait 3,000 years to get our PhD,” Gerdes said.
They found that the amount and composition of olive oil residues in ceramic granules deteriorated in the calcium-rich alkaline soil of Cyprus. Compared to pellets that were buried in slightly acidic New York City soil, pellets in Cyprus soil had lower abundance and loss of vegetable oil dicarboxylic acid biomarkers, which signal the presence of olive oil. While the team didn't test the preserved pots and pans to see what was actually on them if not olive oil, this kind of research does provide another look at the artifacts that have already been discovered. There may be different oils or fats on the heirlooms waiting to be discovered.
“Archaeologists definitely want to believe you found olive oil because it makes for an interesting story,” Gerdes said. “And because it is such an economically important Mediterranean product, the default assumption is that if you found molecules that matched olive oil, then you must have found olive oil.”
The composition of olive oil can sometimes overlap with that of other vegetable oils in clay pots. “And if you start to break it down, it gets even worse—it starts to look like animal fat,” Gerdes said.
Since all reports of ancient olive oil remains may be inaccurate, work remains to be done to figure out which artifacts are actually covered in this delicious oil. It seems that Gerdes will have to continue washing dirty dishes.
