Early human dispersals within the Americas
Early human dispersals within the Americas
复制标题
DOI：
10.1126/science.aav2621
复制
发表时间：
2018-12-07
期刊：
影响因子：
56.9
通讯作者：
Willerslev，Eske
中科院分区：
文献类型：
--
作者：
Moreno-Mayar，J. Victor;Vinner，Lasse;Willerslev，Eske
美洲更新世人类的遗传学研究主要集中在从西伯利亚迁移到北美的时间和数量上。他们表明，祖先美洲原住民（NAs）在约23，000年（约23 ka）前从西伯利亚人和东亚人中分化出来，并且在后来的NAs和古代Beringians（AB）之间的祖先谱系中发生了分裂。随后，NA分支成北方NA（NNA）和南方NA（SNA）分支约15.5 ka前，据推测，分裂发生在东白令加以南，（今阿拉斯加和西部育空地区）。理论根据声称与澳大拉西亚人有亲缘关系的人或具有独特颅形态的人迁移到美洲（“古美洲人”）之前，从西伯利亚和东亚的NA分歧已经产生了争议。同样，美洲人口的增长速度、基底分歧的数量以及不同地区的隔离、混合和连续性程度也知之甚少。为了解决这些问题，我们对从阿拉斯加到巴塔哥尼亚的15个古人类基因组进行了测序，其中6个年龄≥10 ka（覆盖率高达18倍）。所有基因组都与NAs关系最密切，包括两个形态上不同的古美洲人和一个AB个体。然而，我们也发现，以前的模型只是一个粗略的轮廓人口的过程：NA扩散引起了更复杂的序列分裂和早期的人口结构，包括人口的NNA-SNA分裂之前分歧，以及与早期未抽样人口的混合物，这既不是AB也不是NNA或SNA。一旦进入美洲，SNA就广泛而迅速地传播，这一点可以从来自北美和南美的>10 ka前的基因组之间的遗传相似性（尽管物质文化上存在差异）得到证明。到达南美洲后不久，群体沿着沿着多条地理路径分散，在10.4 ka前，这些群体与具有澳大拉西亚血统的人群混合，这可能在早期南美洲人中很普遍。后来，Mesoamerican相关的人口（S）扩大北部和南部，可能标志着相对较小的群体，不一定淹没当地人口的遗传或cultural.CONCLUSIONNAs迅速辐射，并产生了多个群体，一些可见的遗传记录中只作为未抽样的人口的运动。在不同的时期，这些群体扩展到大陆的不同地区，尽管没有最初的人口那么广泛。早期的人口广泛而迅速地传播，这表明他们进入半球的大部分地区基本上是不受限制的，然而，有基因组和考古学暗示早期人类的存在。这些早期的群体，特别是那些有澳大利亚血统的群体，是如何联系或结构的，仍然未知。人口的迅速扩张，加上距离的衰减效应，以及在某些地方，地理和社会障碍，导致了复杂的人口历史。这些包括强大的人口结构在太平洋西北部;隔离在北美大盆地，随后是长期的遗传连续性，并最终一个插曲的混合物早约0.7万年前;和多个独立的，地理上不平衡的迁移到南美洲。其中一次迁徙提供了晚更新世南美洲澳大拉西亚人祖先的线索，而另一次则代表了与中美洲有关的扩张;两者都对今天的南美洲祖先做出了贡献。
INTRODUCTIONGenetic studies of the Pleistocene peopling of the Americas have focused on the timing and number of migrations from Siberia into North America. They show that ancestral Native Americans (NAs) diverged from Siberians and East Asians ~23,000 years (~23 ka) ago and that a split within that ancestral lineage between later NAs and Ancient Beringians (ABs) occurred ~21 ka ago. Subsequently, NAs diverged into northern NA (NNA) and southern NA (SNA) branches ~15.5 ka ago, a split inferred to have taken place south of eastern Beringia (present-day Alaska and western Yukon Territory).RATIONALEClaims of migrations into the Americas by people related to Australasians or by bearers of a distinctive cranial morphology (“Paleoamericans”) before the divergence of NAs from Siberians and East Asians have created controversy. Likewise, the speed by which the Americas were populated; the number of basal divergences; and the degrees of isolation, admixture, and continuity in different regions are poorly understood. To address these matters, we sequenced 15 ancient human genomes recovered from sites spanning from Alaska to Patagonia; six are ≥10 ka old (up to ~18× coverage).RESULTSAll genomes are most closely related to NAs, including those of two morphologically distinct Paleoamericans and an AB individual. However, we also found that the previous model is just a rough outline of the peopling process: NA dispersal gave rise to more complex serial splitting and early population structure—including that of a population that diverged before the NNA-SNA split—as well as admixture with an earlier unsampled population, which is neither AB nor NNA or SNA. Once in the Americas, SNAs spread widely and rapidly, as evidenced by genetic similarity, despite differences in material cultural, between >10-ka-old genomes from North and South America. Soon after arrival in South America, groups diverged along multiple geographic paths, and before 10.4 ka ago, these groups admixed with a population that harbored Australasian ancestry, which may have been widespread among early South Americans. Later, Mesoamerican-related population(s) expanded north and south, possibly marking the movement of relatively small groups that did not necessarily swamp local populations genetically or culturally.CONCLUSIONNAs radiated rapidly and gave rise to multiple groups, some visible in the genetic record only as unsampled populations. At different times these groups expanded to different portions of the continent, though not as extensively as in the initial peopling. That the early population spread widely and rapidly suggests that their access to large portions of the hemisphere was essentially unrestricted, yet there are genomic and archaeological hints of an earlier human presence. How these early groups are related or structured, particularly those with Australasian ancestry, remains unknown. Rapid expansion, compounded by the attenuating effect of distance and, in places, by geographic and social barriers, gave rise to complex population histories. These include strong population structure in the Pacific Northwest; isolation in the North American Great Basin, followed by long-term genetic continuity and ultimately an episode of admixture predating ~0.7 ka ago; and multiple independent, geographically uneven migrations into South America. One such migration provides clues of Late Pleistocene Australasian ancestry in South America, whereas another represents a Mesoamerican-related expansion; both contributed to present-day South American ancestry.NA dispersal and divergence over timeSchematic …