〇Oki NAKAMURA (Ritsumeikan University), Yosuke KAWAI (National Center for Global Health and Medicine), Katsunori TAKASE (Hokkaido University), Yuji YAMAGUCHI (Okayama University), Corey NOXON (Ritsumeikan University)
Group B05 aims to conduct population estimates with high temporal and spatial resolution, mainly for the Jomon period, based on statistical analysis of archaeological, human skeletal, and environmental data and natural science analysis. In FY2023, the group worked on data construction and improved analytical methods. In FY2024, we will continue these efforts and prepare to conduct several different demographic studies in the same region and period. The following is a summary of the members' research results.
１．Demographic estimates of the Jomon period based on the number of archaeological sites in the northern Tohoku region (Nakamura)
We have developed a population estimation method that takes advantage of both the number of archaeological sites with lower discovery bias and the number of dwellings with easier estimation of total population (Figure 1). It is possible to estimate the average number of people per year in a regional unit over a 100-year range. Based on the type and timing of pottery excavated at the sites, a probability of existence is given for each site for each 100-year-wide time block. For this purpose, we developed a time block that divides the earthenware chronology with the calendar chronology from the Initial to Final Jomon period into 100 year-wide time blocks. The sum of presence probabilities for each time block gives an approximation of the average annual number of site presence for each 100-year range (Fig. 1). Multiplying this by an appropriate coefficient yields an estimate of the average annual population, and the time-series data at 100-year intervals allows us to accurately grasp the speed and magnitude of population change. In the construction of the data for the Aomori Prefecture area, data from about 620 reports were entered. We can point out the possibility that several large population waves occurred after the middle of the Early Jomon period (around 5,900 cal BP).
２．Population history of Japanese population inferred from whole genome data (Kawai)
This year, we mainly conducted analysis and database construction for the preparation of genome information for analysis. We received genomic information obtained by whole genome sequencing analysis (WGS analysis) obtained from the analysis of biobanks in the National Center Biobank Network. In addition, we received genomic data obtained by WGS analysis obtained from the Okinawa Bioinformation Bank provided by the University of the Ryukyus and the Yaponesia Genome, a new academic research area. An ethical application to use these genomic data of modern Japanese in this study was submitted to and approved by the Ethics Review Committee of the National Center for Global Health and Medicine. In addition to the genomic data of contemporary Japanese, WGS analysis data of various populations around the world obtained from public databases were added for data integration. Specifically, a single dataset was created from the GRCh38 mapping data by performing a variant call using the GATK Haplotype Caller and then performing a joint call (Fig. 2). In addition, in order to estimate the past population from ancient human genome data, genome data collected in the Japanese archipelago, such as the Yaponesian genome study, were provided by Group B04, Hideaki Kanzawa. In addition, ancient human genomes obtained from the analysis of human remains excavated from archaeological sites mainly in East Asia were downloaded from public databases. We performed imputation using haplotype information of modern humans and constructed an analytical dataset containing a number of variants comparable to that of whole genome analysis.
３． Isotopic analysis of northern fur seals and cod from excavations in northern and eastern Hokkaido (Takase)
In Hokkaido, which has been highly dependent on marine resources for a long period of time, there may have been some relationship between past marine productivity and population change. To test this hypothesis, we conducted nitrogen, carbon, and oxygen isotope analyses of 51 northern fur seals (Callorhinus ursinus) and 39 cod (Gadus macrocephalus) excavated from six northern Hokkaido and five eastern Hokkaido sites. The δ15N of northern fur seals was lower in the Early and Late Jomon in eastern Hokkaido, but this may reflect differences in growth stage due to smaller size in eastern Hokkaido than in northern Hokkaido. The low linkage between northern fur seal and cod in all isotopes may reflect the marine environment of the western North Pacific for northern fur seals and the Hokkaido coast for cod, considering the difference in migration range. For cod, δ13C is higher in eastern Hokkaido than in northern Hokkaido, and there is a clear trend toward lower δ15N and δ18O from the Sequential Jomon to Okhotsk cultures. We can assume that not only marine productivity but also human fishing activities, population structure and migration routes have changed as factors. It is estimated that the population of the East Hokkaido region increased during the Okhotsk culture period and then declined consistently. The decline in population after the end of the Abrahamic Culture may be related to the decline in marine productivity, but this does not explain the population increase during the Okhotsk Culture. Interpretation is still difficult because other factors, such as the advance of an abraded culture to the east of Hokkaido during this period, are also relevant. In the future, we plan to use ancient DNA analysis and amino acid isotope analysis in combination to determine the background.
- (Research note) Katsunori Takase, Yoshinori Nishida, and Keisuke Ushiro 2024, "DNA Analysis and Carbon, Nitrogen, and Oxygen Stable Isotope Analysis of the Remains of the Northern Fur Seal: Excavated Materials from the Joro Eiura 1 and Omisaki 1 Sites in Wakkanai City, Hokkaido, in the Collection of Hokkaido Museum," Bulletin of the Hokkaido Museum. 9: 37-52.
- (Conference presentation) Katsunori Takase, Yoshinori Nishida, and Takumi Tsutaya 2024, "DNA and isotope analysis of northern fur seals and codfish excavated from archaeological sites," 23rd North Asian Research Report Meeting (March 2, University of Tokyo, Japan).
４．Insights into mobility through reconstruction of dwellings (Noxon)
This year, we proceeded to collect data for two different approaches to better understand the demographics of the Jomon period. The first is the quantification of the materials and energy resources required to construct the various forms of Jomon-era dwellings. Prior studies have confirmed a link between mobility and the amount of energy required to construct dwellings. As an experimental archaeological model, a 3D model was constructed based on scans of dwelling sites and reconstructed dwellings. This is used to estimate energy consumption for material procurement and construction. If quantitative differences between different dwelling types can be identified, changes in dwelling types used could be associated with changes in mobility in habitation. Next, GIS data on slopes, views, and distance to water sources were collected using the Tama area of Tokyo and the Hokuto City area of Yamanashi Prefecture as case study areas. By estimating the likely locations of archaeological sites based on geographical features, it is possible to evaluate cases where current archaeological site distribution data may not be straightforwardly indicative of the original site distribution.
５．Formation process of storage pits (Yamaguchi)
Some of the low marsh type storage pits in western Japan have few excavated artifacts, making it difficult to determine the timing of their formation. It is difficult to discuss whether the pits are the product of a single period or the result of continuous use. The above question is important because the number and capacity of storage pits are sometimes used as a basis for estimating the size of the population. Therefore, we conducted dating of a group of storage pits at the Minamikata-Maeike site located in Akaiwa City, Okayama Prefecture. Based on excavated pottery, the storage pits at this site have been thought to be the product of a single period. The results of the dating indicate that the storage pits were used in two separate periods, but the number of simultaneous use of the pits was small, suggesting that the storage pits were formed as a result of continuous use. This result may have implications for issues such as group, population, and settlement pattern.
- Yuji Yamaguchi 2023 "The Formation Process of Storage Pit Groups: Dating Results from the Minamikata-Maeike Site, Okayama Prefecture, Japan" 89th Annual Meeting and Conference of the Japanese Archaeological Association (Sendai, Japan).
- Yuji Yamaguchi 2024 "The Jomon Period in Okayama: Environment, Culture, and Population," Nature and Culture of Okayama 43: 53-102.