Ancient mitochondrial DNA provides high-resolution time scale of the peopling of the Americas

The exact timing, route, and process of the initial peopling of the Americas remains uncertain despite much research. Archaeological evidence indicates the presence of humans as far as southern Chile by 14.6 thousand years ago (ka), shortly after the Pleistocene ice sheets blocking access from eastern Beringia began to retreat. Genetic estimates of the timing and route of entry have been constrained by the lack of suitable calibration points and low genetic diversity of Native Americans. We sequenced 92 whole mitochondrial genomes from pre-Columbian South American skeletons dating from 8.6 to 0.5 ka, allowing a detailed, temporally calibrated reconstruction of the peopling of the Americas in a Bayesian coalescent analysis. The data suggest that a small population entered the Americas via a coastal route around 16.0 ka, following previous isolation in eastern Beringia for ~2.4 to 9 thousand years after separation from eastern Siberian populations. Following a rapid movement throughout th...

尽管已有大量研究，美洲大陆的首次人类定居的精确时间、迁徙路线与过程仍未明确。考古证据表明，早在14.6千年前（ka），人类就已抵达智利南部区域，彼时阻隔白令东部地区（eastern Beringia）对外通道的更新世冰盖正处于消退初期。此前，由于缺乏合适的校准位点，且美洲原住民遗传多样性较低，基于遗传学的定居时间与路线估算始终难以获得准确结果。本研究对92例前哥伦布时期（pre-Columbian）南美骨骼样本的完整线粒体基因组（mitochondrial genome）进行了测序，样本年代跨度为8.6至0.5 ka。通过贝叶斯溯祖分析（Bayesian coalescent analysis），我们得以构建经时间校准的美洲大陆首次人类定居详细重建模型。研究数据显示，一小部分人群在与东西伯利亚人群分离后，曾在白令东部地区隔离约2.4至9千年，随后于约16.0 ka沿沿海路线进入美洲，并在此后快速扩散至整个美洲大陆……