Traces of sea mammals on pottery from the Hamanaka 2 archaeological site, Rebun Island, Japan: Implications from sterol analysis, stable isotopes, and radiocarbon dating

Abstract

To reconstruct prehistoric human diets, we studied pottery excavated from the Hamanaka 2 archaeological site, Rebun Island, Hokkaido, Japan, where marine mammals were cooked (boiled) in pottery vessels to obtain animal oils and fats. We analyzed lipids adhering to the pottery and demonstrated that cholesterol made up more than 80% of the detected sterols, suggesting that they were of animal origin. The stable isotopes of carbonized material adhering to the inner surfaces of potsherds indicated that the charred materials likely refl ected a diet of marine mammals or fi nfi shes. Radiocarbon dates on the same charred materials showed a large marine reservoir effect, which supported the interpretation that they were derived from marine products cooked in the pottery vessels. The apparent radiocarbon age differences between the charred materials on the inner surfaces of the potsherds and charred wood from the same layer that the potsherds came from indicated a correction value for the marine reservoir effect (ΔR) in the northwestern Pacifi c of 444 ± 55 14C years at 3010 BP. The results of these three analyses, namely, sterol analysis, stable isotope analysis, and radiocarbon dating, are consistent with the archaeological hypothesis that during the latter half of the Late Jomon period (1300–1200 cal BC), sea mammals were cooked in pottery vessels to obtain animal oils and fats at the Hamanaka 2 archaeological site. * N ational Museum of Japanese History, 117 Jonai-cho, Sakura, Chiba 285-8502, Japan ** College of Liberal Arts, International Christian University, 10-2 Osawa, 3-chome, Mitaka, Tokyo 181-8585, Japan *** Paleo Labo Co. Ltd., AMS Dating Facility, 1900-65, Shimo-tazawa, kurohone-cho, kiryu, Gunma 376-0144, Japan a Corresponding author: e-mail: miyata@nendai.nagoya-u.ac.jp Present address: Center for Chronological Research, Nagoya University, Furou-cho, Chikusa, Nagoya 464-8602, Japan