Hairs in old books isotopically reconstruct the eating habits of early modern Japan

要旨

Abstract To complement literature-based historical knowledge of the eating habits of 17th- and 18th-century Japan, we analysed carbon and nitrogen isotope ratios ( δ 13 C and δ 15 N, respectively) of human hairs embedded in cover paper of Japanese books printed during 1690s–1890s, taking regional and temporal variations into consideration. We purchased 24 book sets from second-hand book markets. Twenty-three sets contained enough human hairs, which were non-destructively extracted from the thick, recycled paper of the book covers and used to measure the δ 13 C and δ 15 N values, found to be identical within each book set. Relatively low δ 13 C values and high δ 15 N values suggested that people depended on rice, C 3 vegetables, and fish, more exclusively than contemporary Japanese people. The relatively high δ 13 C values found in Edo (Tokyo) might be associated with the preference for C 4 millets by Edo people as a measure against beriberi (locally recognised as the Edo affliction). The δ 15 N values gradually increased over 200 years, indicating an increase in the contribution of marine fish both as food and fertiliser for rice fields as suggested by literature-based studies. Further collection of hairs from books will enable a thorough examination of regional and temporal variations to better understand the pre-globalised food culture.

主題