Centuries-old plaque on eight people’s teeth preserved a surprisingly detailed menu of what they ate in Osaka

Nearly 400 years ago, people living in Osaka had no refrigerators, supermarkets or modern food supply chains. Yet an unusual scientific discovery suggests that their diets were far more varied than expected. Researchers analysing hardened dental plaque from eight people buried at the Umeda cemetery in Osaka identified 38 dietary proteins from 17 types of food, offering a rare glimpse into what ordinary people ate during Japan’s Edo period. The study, published in Anthropological Science, was conducted by researchers from the Graduate University for Advanced Studies (SOKENDAI), Aomori Public University, Kyushu University and other institutions.Their teeth became a food recordThe researchers examined dental calculus, hardened plaque that can preserve microscopic traces of what people consumed.They combined palaeoproteomic analysis of the calculus with carbon and nitrogen isotope analysis of bone collagen. The isotope results indicated diets based largely on terrestrial plants and marine resources, while the proteins trapped in dental calculus provided much more specific clues about individual foods.⁠Across the eight individuals, scientists identified proteins belonging to nine fish t...