100万年前の頭蓋骨「雲県2号」が人類進化の年表を刷新(Yunxian 2 from China Rewrites Human Evolution Timeline)

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2025-09-28 中国科学院(CAS)

中国科学院古脊椎動物・古人類研究所を中心とする国際チームは、1990年に湖北省で発見された約100万年前のヒト化石「雲仙2号頭蓋骨」を最新のデジタル復元技術で再解析しました。従来はホモ・エレクトスに分類されていましたが、再構成により、前額部の低平さなど原始的特徴と大脳容積の大きさや頬骨の平坦さなど進化的特徴を併せ持つことが判明。これにより、雲仙2号は「龍人(Homo longi)」系統の初期個体であり、デニソワ人との近縁性が強く示唆されました。系統解析の結果、ホモ・サピエンス、ネアンデルタール人、龍人系統の分岐は従来よりも遥かに早期に起こっていたとされ、人類進化史の複雑性を浮き彫りにしました。本研究は「ミドル・プレイストシーンの混乱」と呼ばれる化石群の位置づけを整理する上で重要な成果です。

100万年前の頭蓋骨「雲県2号」が人類進化の年表を刷新(Yunxian 2 from China Rewrites Human Evolution Timeline)
The human family tree. (Image by NI Xijun, BAI Jiannan)

<関連情報>

雲仙人の頭蓋骨の系統学的位置はホモ・ロンギとデニソワ人の起源を解明する The phylogenetic position of the Yunxian cranium elucidates the origin of Homo longi and the Denisovans

Xiaobo Feng, Qiyu Yin, Feng Gao, Dan Lu, […] , and Xijun Ni
Science  Published:25 Sep 2025
DOI:https://doi.org/10.1126/science.ado9202

Editor’s summary

It is now well known that there were at one time many Homo lineages. Understanding of the differences among these lineages is largely dependent upon crania that are rare and often damaged and deformed by age. Feng et al. reconstructed the 1-million-year-old Yunxian 2 cranium using an approach that allowed for removal of much of the compression and distortion naturally present in the fossil. In doing so, they found that the cranium contained both primitive and derived traits and concluded that it is representative of the H. longi clade, which is sister to H. sapiens and likely contained the Denisovans. —Sacha Vignieri

Abstract

Diverse forms of Homo coexisted during the Middle Pleistocene. Whether these fossil humans represent different species or clades is debated. The ~1-million-year-old Yunxian 2 fossil from China is important for understanding the cladogenesis of Homo and the origin of Homo sapiens. In this study, we restored and reconstructed the distorted Yunxian 2 cranium using recently introduced technology. The results show that this cranium displays mosaic primitive and derived features. Morphometric and phylogenetic analyses suggest that it is an early member of the Asian H. longi clade, which includes the Denisovans and is the main part of the sister group to the H. sapiens clade. Both the H. sapiens and H. longi clades have deep roots extending beyond the Middle Pleistocene and probably experienced rapid early diversification. Yunxian 2 may preserve transitional features close to the origins of the two clades.

生物工学一般
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