The Sahara is the largest hot desert on Earth. Yet the timing of its inception and its response to climatic forcing is debated, leading to uncertainty over the causes and consequences of regional aridity. Here we present detailed records of terrestrial inputs from Africa to North Atlantic deep-sea sediments, documenting a long and sustained history of astronomically paced oscillations between a humid and arid Sahara from over 11 million years ago. We show that intervals of strong dust emissions from the heart of the continent predate both the intensification of Northern Hemisphere glaciation and the oldest land-based evidence for a Saharan desert by millions of years. We find no simple long-term gradational transition towards an increasingly arid climate state in northern Africa, suggesting that aridity was not the primary driver of gradual Neogene expansion of African savannah C₄ grasslands. Instead, insolation-driven wet–dry shifts in Saharan climate were common over the past 11 Myr, and we identify three distinct stages in the sensitivity of this relationship. Our data provide context for evolutionary outcomes on Africa; for example, we find that astronomically paced arid intervals predate the oldest fossil evidence of hominid bipedalism by at least 4 Myr.

撒哈拉沙漠是地球上最大的炎热沙漠。然而，它开始的时间和它对气候强迫的反应存在争议，导致对区域干旱的原因和后果的不确定性。在这里，我们提供了从非洲到北大西洋深海沉积物的陆地输入的详细记录，记录了 1100 万年前潮湿和干旱的撒哈拉沙漠之间的天文节奏振荡的长期和持续历史。我们表明，从北半球冰川作用的加剧和撒哈拉沙漠最古老的陆基证据开始，大陆中心的强烈尘埃排放间隔早了数百万年。我们发现没有简单的长期逐步过渡到北非日益干旱的气候状态，_4个草原。相反，在过去的 11 Myr 中，日射驱动的撒哈拉气候干湿变化很常见，我们确定了这种关系敏感性的三个不同阶段。我们的数据为非洲的进化结果提供了背景；例如，我们发现天文节奏的干旱间隔比人类两足行走的最古老化石证据至少早了 4 Myr。