Centuries-old plaque preserved on human teeth is giving researchers an unusually personal look at what ordinary people ate in Osaka during Japan’s Edo period, which lasted from 1603 to 1868.
In a study of eight adults buried in Osaka during that era, researchers found traces of foods ranging from sea bream and other fish to meat and plants. The findings suggest that at least some ordinary city residents had access to a surprisingly varied diet, including seafood brought from distant parts of Japan.
The study, published in Anthropological Science, used hardened dental plaque, called dental calculus, to look for proteins left behind by food. Researchers also analyzed the bones to get a broader picture of the types of foods these people ate.
Together, those methods helped answer a simple question: Osaka was famous for having a rich food supply, but did ordinary people actually get to eat that food?
At the time, Osaka was a major center for food trade and distribution and was known as the “Kitchen of the Realm.” Food arrived from nearby waters as well as more distant parts of Japan. But a city having plenty of food does not necessarily mean everyone living there could afford or obtain it.
The eight people in the study were buried at Umeda Cemetery, a burial ground used by commoners. Researchers found 38 food-related proteins linked to 17 groups of animals and plants. Fish proteins appeared in seven of the eight people.
One of the most common findings was red sea bream, detected in six people.
Historical sources describe sea bream as a prized fish, but that does not mean every piece was an expensive luxury. The researchers note that size, quality, season and availability likely affected price, and sea bream was especially abundant during parts of the year.
Still, its presence suggests that a fish associated with higher status could also reach ordinary city residents.
Other findings show just how far Osaka’s food network extended.
Researchers found proteins from salmon-family fish, even though those cold-water fish do not naturally live around Osaka Bay. Historical records show that seafood from northern Japan and the Sea of Japan coast was shipped to Osaka over long distances.
That means some of these people were eating food that had traveled hundreds of miles before reaching the city.
The researchers also found evidence of meat.
Proteins from nonhuman mammals appeared in four of the eight people. Some were linked to animals such as wild boar and badger.
Meat eating was restricted by religious and social customs during much of the Edo period, but historical records show that people still ate it. In some cases, meat was described as medicinal food, which offered a socially acceptable reason for eating it.
The dental plaque adds another piece of evidence that meat was not just mentioned in old books or found in archaeological trash. Some ordinary people appear to have actually eaten it.
One of the strangest findings involved proteins matching goldfish or closely related freshwater fish. Those proteins appeared in three people.
The researchers cannot say for sure that anyone was eating goldfish because closely related fish can have very similar proteins. But the idea is not completely out of place historically. A Japanese food and herbal text from the 1600s listed goldfish among edible fish.
Another unusual finding involved cottonseed protein in one person.
That result is much harder to interpret. The protein could have come from a processed cottonseed product, medicinal use or even accidental exposure related to work. The researchers do not have enough evidence to say the person was eating cottonseed oil.
The study also comes with important limits.
Eight people cannot tell us what everyone in Osaka ate. The researchers selected remains that were well preserved, and dental plaque only captures fragments of someone’s diet.
Finding a food protein means a person was exposed to or likely consumed that food, but it does not show how often they ate it, how much they ate or whether it was a regular part of their diet.
And if researchers did not find a particular food, that does not mean the person never ate it.
Even with those limits, the study offers something historical records often cannot: evidence connected directly to ordinary people who left behind no diaries, cookbooks or detailed accounts of their meals.
For these eight Osaka residents, at least, living in one of Japan’s great food cities appears to have meant access to more than just local staples. Their diets included prized fish, food transported from distant regions and foods that did not always fit neatly with the social rules of the time.
The research was supported in part by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science and a Joint Research Grant for the Environmental Isotope Study from the Research Institute for Humanity and Nature.