Late-Glacial bifacial microblade core technologies in Hokkaido : An implication of human adaptation along the northern Pacific Rim

The wedge-shaped microblade core technology found along the northern Pacific Rim has been regarded as a trait of hunter-gatherer adaptation during the Late Glacial and initial Holocene. Having recognized variable microblade core reduction methods among the technocomplexes in Hokkaido, by employing an optimization model in lithic technology, the present paper addresses the question of what role bifacial microblade core technologies played in foraging, through a comparative analysis of utility, cost of transportation, and failure rates between the larger ("Sakkotsu") and smaller ("Oshorokko") bifacial microblade core technologies in the Late Glacial Hokkaido. Results suggest that as opposed to the larger bifacial microblade core technology, the smaller bifacial microblade core technology was more effective for exploring unpredictable environment across the northern Pacific Rim

Human responses to the Younger Dryas in Japan

The effect of the Younger Dryas cold reversal on the survival of Late Glacial hunter-gatherers in the Japanese Archipelago is evaluated, through a synthetic compilation of 14C dates obtained from excavated Late Glacial and initial Holocene sites (332 14C dates from 88 sites). The estimated East Asian monsoon intensity and vegetation history based on the loess accumulations in varved sediments and pollen records in and around the Japanese Archipelago suggest an abrupt change to cool and dry climate at the onset of Younger Dryas, coupled with the Dansgaard–Oeschger Cycles as recorded in Greenland. The chronometric placement of sites based on an assessment of 14C dates show that the site numbers decrease from the Bølling–Allerød to Younger Dryas and increase from the Younger Dryas to Preboreal. However, human population dynamics inferred from a site distribution analysis was little changed from the previous Bølling–Allerød and to the following Preboreal. Moreover, hunter-gatherers consistently employed ceramic pottery technology since its emergence prior to the onset of Younger Dryas, while the quantity of ceramic vessels that were undermined during the Younger Dryas dramatically increased at the onset of the Holocene, implying that a substantial change in hunter-gatherer socioeconomy occurred after the end of Younger Dryas

A systematic comparison of obsidian hydration measurements : The first application of micro-image with secondary ion mass spectrometry to the prehistoric obsidian

Archaeologists have long used obsidian hydration dating method to give chronometric dates for obsidian artifacts. Models using these equations independently employ different measurement systems, which are based on rim thicknesses determined by optical microscope and hydrogen depths measured by secondary ion mass spectrometry (SIMS), respectively, although the inconsistency of both measurements has been reported. Firstly, this paper describes a systematic comparison that was done on optical rim thicknesses and hydrogen depths by means of an isotope microscope, which provides micro-imaging with SIMS. Depth profiles of hydrogen were precisely obtained from the spots where optical measurements were taken on the archaeological obsidian flakes from two distinctive cultural horizons (older: Upper Paleolithic, younger: Initial Jomon) in the stratified open-air site of Jozuka in southern Kyushu (Japan). Secondarily, using the measurements of hydrogen depths that are the most consistent to the measurements of optical thicknesses, the estimated hydration rate of the Holocene (Initial Jomon) is slower than that of the Late Pleistocene (Upper Paleolithic), implying that the difference in hydration rates was due to the difference of intrinsic water content of obsidian and/or obsidian geochemistry. An application of micro-imaging with SIMS to measure hydrogen depths on obsidian shows promise as a tool for improving the practice of hydration dating and evaluating local climatic condition