Sure, astrophysicists have large telescopes and oceanographers use underwater robots, but some researchers manage to cook venison, in abundance, in the name of science.
Last month in Scientific Reports, a team of archaeologists and organic chemists described how they had spent a year cooking a variety of meals in clay pots and then investigating the organic residue left behind. No one got a big meal from this lab work, but the researchers found that some residues only tracked the last round of ingredients, while others reflected each pot’s long-term culinary history. By documenting the results of these experiments, the team hopes to help scientists reconstruct ancient culinary practices.
One way to learn about food preferences and practices over time is to look at what’s left after a meal. As they are used, kitchen vessels naturally accumulate organic residues such as charred pieces, thin coatings known as patinas and absorbed fats. The sponges and dishwashers we use today tend to eradicate these leftovers, but they are often found in and on kitchen utensils found in archaeological sites.
There is much to learn from studying these leftovers, said John P. Hart, an archaeologist at the New York State Museum in Albany who was not involved in the research. “It’s a way to better understand how people lived in the past and what they ate.”
Dr. Swift and her colleagues designed a culinary experiment using unglazed clay pots from central Colombia. Clay can absorb food residues and thus provides a record of past meals, said Melanie J. Miller, an archaeologist at the University of Otago in New Zealand and another co-author. But that’s only the case if the clay isn’t glazed, he said, adding, “When you have glaze on a pot, it acts as a barrier.”
Seven members of the research team volunteered to cook. Each archaeologist-cook received a pot and prepared the same meal there once a week for 50 weeks. Each then moved on to a different meal for another one to four weeks.
The preparations were based on wheat and corn. “It worked well that we had the representation of two foods that were really central to diets in major parts of the world, but also chemically seem quite different,” said Dr. Miller.
Venison also made its appearance in three meals. “We had a roadkill deer,” said Dr. Miller, adding that no one ate what he had cooked.
Between meals, the researchers hand washed the pots with water. If necessary, they also used a small branch of an apple tree as an additional washing tool. “We spent a lot of time thinking about how we could be as true to the past as possible,” said Dr. Swift.
During the experiment, the researchers collected samples from their vessels for analysis. They picked up small bits of charred food, scraped up bits of patina, and pierced the pots to collect the absorbed fat. In the laboratories of the University of California, Berkeley and the University of Bristol in England, the team analyzed the carbon and nitrogen content of the samples.
They found that the charred remains tended to reflect only the most recent ingredients cooked in a pot, which was no surprise. However, the researchers showed that the patinas had longer culinary memories. As they pondered the last meal strongly, “we see these little hints of things that have been cooked in the pot before,” said Dr. Miller. And the absorbed fats remembered the most, the team found that they tended to be overwritten the slowest.
“We’re getting these three different time scales of history,” said Dr. Miller.
These findings could shed light on the different components of ancient diets, the researchers suggested. Just like people today, civilizations of the past haven’t always cooked the same thing, said Dr. Swift, adding, “That richness of history is often lost.”