縄文人の人口、縄文時代のはじまりに急増~古人骨由来ミトコンドリアDNA配列から独自の人口史に迫る~

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2026-01-30 東京大学

東京大学の研究グループは、縄文人骨由来のミトコンドリアDNA(mtDNA)全塩基配列を用いて、縄文人の人口史を直接復元した。千葉県市原市の遺跡から出土した13個体の新規データと既存データを合わせ、計40個体を解析した結果、縄文草創期から早期(約1万3千~8千年前)という縄文時代の初期段階で、縄文人集団が顕著な人口増加を経験していたことが明らかになった。これは考古学的推定とも整合的であり、現代日本人のDNA解析では見えなかった縄文人固有の人口動態を示す初の成果である。また、mtDNA系統M7aとN9bに見られる東西頻度差は、複数移住を仮定せずとも、単一起源集団の拡散と遺伝的浮動によって生じ得ることをシミュレーションで示した。本研究は、日本列島における先史時代人類の定住と拡散の理解を大きく前進させるものである。

縄文人の人口、縄文時代のはじまりに急増~古人骨由来ミトコンドリアDNA配列から独自の人口史に迫る~
縄文人および現代日本人の有効集団サイズ(Ne)の変化

<関連情報>

縄文人の人口動態史:全ミトコンドリアゲノム解析からの知見 Demographic history of the Jomon people: insights from whole-mitogenome analysis

Koki Yoshida, Yoshiki Wakiyama, Yuka Nakamura, Guido Valverde, Akio Tanino, Daisuke Waku, Takafumi Katsumura, Motoyuki Ogawa, Tomohito Nagaoka, Kazuaki Hirata, Kae Koganebuchi, Yusuke Watanabe, Jun Ohashi, Minoru Yoneda, Ryuzaburo Takahashi, Hiroki Oota
Anthropological Science  Published:January 30, 2026
DOI:https://doi.org/10.1537/ase.251024

Abstract

The Jomon culture that spread across the Japanese archipelago began about 16000 years ago and lasted for over 10000 years. The population history of the Jomon people, prehistoric hunter-gatherers bearing the Jomon culture, is of great interest in understanding prehistoric East Eurasians. Traditionally, population size and its fluctuations, i.e. Jomon demography, have been estimated in the archaeological context, but over the past 20 years, statistical methods using genome sequence data have been sufficiently developed. To investigate their demography, we determined the complete whole-mitochondrial genome (mitogenome) sequences from 13 Jomon individuals and conducted population genetic analysis on 40 Jomon mitogenomes, including previously published data. By simulation, we showed that east–west frequency differences between two haplogroups typical of the Jomon people, N9b and M7a, could be caused by a genetic drift under conditions of a small initial effective population size, an extreme population split, and limited migration between the eastern and western populations, suggesting that the regionally unbalanced haplogroup distribution does not necessarily contradict the monophyletic origin scenario of the Jomon people implied by recent nuclear genome analyses. We found an effective population size (Ne) increase during the Incipient–Initial phase of the Jomon period, which had not been observed in analyses of mitogenome sequences from present-day Japanese populations. This endemic demographic pattern is pronounced in the eastern part of the archipelago, under the assumption of no gene flow between the Eastern and Western Jomon. This study sheds light on the demography of the Jomon people and shows an alternative scenario of the Jomon peopling history estimated based on whole-mitogenome data.

生物工学一般
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