Early contact during the 5th millenium in southeastern Europe

Archaeogenetic studies have described two major genetic turnover events in prehistoric western Eurasia: one associated with the spread of farming and a sedentary lifestyle starting ~7000-6000 BCE, and a second with the expansion of pastoralist groups from the Eurasian steppes starting ~3300 BCE. The period between these events saw new economies emerging on the basis of key innovations, including metallurgy, wheel and wagon, and horse domestication. However, what happened between the demise of the Copper Age settlements ~4250 BCE and the expansion of pastoralists remains poorly understood. To address this question, we analysed genome-wide data from 135 ancient individuals from the contact zone between southeastern Europe and the northwestern Black Sea region spanning this critical time period. While we observe genetic continuity between Neolithic and Copper Age groups from major sites in the same region, from ~4500 BCE on, groups from the northwestern Black Sea region carried varying amounts of mixed ancestries derived from Copper Age groups and those from the forest/steppe zone, indicating genetic and cultural contact over a period of ~1000 years earlier than anticipated. We propose that the transfer of critical innovations between farmers and transitional foragers/herders from different eco-geographic zones during this early contact was integral to the formation, rise and expansion of pastoralist groups ~3300 BCE.

考古遗传学研究已阐明史前欧亚西部存在两次主要的遗传更替事件：第一次与公元前7000至6000年左右农业的传播及定居生活方式的普及相关，第二次则与公元前3300年左右欧亚草原（Eurasian steppes）游牧群体的扩张有关。两次事件之间的时段内，依托冶金、轮车与马驯化等关键技术革新，新兴经济形态逐步兴起。然而，公元前4250年左右铜器时代（Copper Age）聚落消亡至游牧群体扩张之间的这段时期，目前仍有待深入探究。为解答这一科学问题，本研究对覆盖该关键时段的、位于东南欧与黑海西北沿岸交界地带的135例古代个体开展了全基因组数据（genome-wide data）分析。尽管我们观察到同一区域主要遗址的新石器时代（Neolithic）与铜器时代群体间存在遗传连续性，但自公元前4500年左右起，黑海西北沿岸区域的群体携带了不同比例的、源自铜器时代群体与森林/草原地带群体的混合祖源成分，这表明遗传与文化交流的出现时间比此前预期早了约1000年。我们提出，在此次早期接触过程中，不同生态地理区域的农耕者与过渡性觅食者/牧民之间的关键技术革新传播，是公元前3300年左右游牧群体形成、崛起与扩张的核心要素。