Although modern humans left Africa multiple times over 100,000 years ago, those broadly ancestral to non-Africans dispersed less than 100,000 years ago¹. Most models hold that these events occurred through green corridors created during humid periods because arid intervals constrained population movements². Here we report an archaeological site—Shinfa-Metema 1, in the lowlands of northwest Ethiopia, with Youngest Toba Tuff cryptotephra dated to around 74,000 years ago—that provides early and rare evidence of intensive riverine-based foraging aided by the likely adoption of the bow and arrow. The diet included a wide range of terrestrial and aquatic animals. Stable oxygen isotopes from fossil mammal teeth and ostrich eggshell show that the site was occupied during a period of high seasonal aridity. The unusual abundance of fish suggests that capture occurred in the ever smaller and shallower waterholes of a seasonal river during a long dry season, revealing flexible adaptations to challenging climatic conditions during the Middle Stone Age. Adaptive foraging along dry-season waterholes would have transformed seasonal rivers into ‘blue highway’ corridors, potentially facilitating an out-of-Africa dispersal and suggesting that the event was not restricted to times of humid climates. The behavioural flexibility required to survive seasonally arid conditions in general, and the apparent short-term effects of the Toba supereruption in particular were probably key to the most recent dispersal and subsequent worldwide expansion of modern humans.

尽管现代人类在 10 万多年前多次离开非洲，但非非洲人的祖先在不到 10 万年前就分散了¹。大多数模型认为，这些事件是通过潮湿时期创建的绿色走廊发生的，因为干旱时期限制了人口流动²。在这里，我们报告了一个考古遗址——Shinfa-Metema 1，位于埃塞俄比亚西北部的低地，其中最年轻的多巴凝灰岩隐石质可以追溯到大约 74,000 年前——它提供了早期和罕见的证据，表明在可能采用弓和箭。饮食包括多种陆生和水生动物。来自哺乳动物牙齿化石和鸵鸟蛋壳的稳定氧同位素表明，该地点是在季节性干旱时期被占领的。鱼类的异常丰富表明，在漫长的旱季期间，鱼类的捕捞发生在季节性河流中越来越小、越来越浅的水坑中，这揭示了中石器时代对挑战性气候条件的灵活适应。沿着旱季水坑进行适应性觅食可能会将季节性河流转变为“蓝色高速公路”走廊，有可能促进非洲以外的扩散，并表明该事件并不局限于潮湿气候时期。一般来说，在季节性干旱条件下生存所需的行为灵活性，尤其是多巴超级喷发的明显短期影响，可能是现代人类最近的扩散和随后在全球范围内扩张的关键。