Department of Infectious Diseases, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Parkville, VIC, Australia.
Commun Biol. 2023 Oct 13;6(1):1037. doi: 10.1038/s42003-023-05388-8.
The Two Layer hypothesis is fast becoming the favoured narrative describing East Asian population history. Under this model, hunter-gatherer groups who initially peopled East Asia via a route south of the Himalayas were assimilated by agriculturalist migrants who arrived via a northern route across Eurasia. A lack of ancient samples from tropical East Asia limits the resolution of this model. We consider insight afforded by patterns of variation within the human pathogen Mycobacterium tuberculosis (Mtb) by analysing its phylogeographic signatures jointly with the human Y-chromosome. We demonstrate the Y-chromosome lineages enriched in the traditionally hunter-gatherer groups associated with East Asia's first layer of peopling to display deep roots, low long-term effective population size, and diversity patterns consistent with a southern entry route. These characteristics mirror those of the evolutionarily ancient Mtb lineage 1. The remaining East Asian Y-chromosome lineage is almost entirely absent from traditionally hunter-gatherer groups and displays spatial and temporal characteristics which are incompatible with a southern entry route, and which link it to the development of agriculture in modern-day China. These characteristics mirror those of the evolutionarily modern Mtb lineage 2. This model paves the way for novel host-pathogen coevolutionary research hypotheses in East Asia.
两层假说迅速成为描述东亚人群历史的首选叙事。在这个模型中，最初通过喜马拉雅山以南的路线进入东亚的狩猎采集者群体被通过欧亚大陆北部路线到达的农业移民所同化。来自热带东亚的古代样本的缺乏限制了该模型的分辨率。我们通过分析人类病原体结核分枝杆菌 (Mtb) 的变异模式来考虑其种系地理学特征，同时考虑人类 Y 染色体。我们证明，与东亚最初的人口迁徙层相关的传统狩猎采集群体中丰富的 Y 染色体谱系具有深厚的根源、低长期有效种群大小和与南部进入路线一致的多样性模式。这些特征与进化上古老的 Mtb 谱系 1 相吻合。其余的东亚 Y 染色体谱系几乎完全不存在于传统的狩猎采集群体中，并且具有与南部进入路线不兼容的时空特征，将其与现代中国农业的发展联系起来。这些特征与进化上现代的 Mtb 谱系 2 相吻合。该模型为东亚的新型宿主-病原体协同进化研究假说铺平了道路。
