Eleusine coracana (finger millet) is a nutritious and easily storable grain that can be grown in unfavourable environments and is important to the food security of millions of farmers in Africa and South Asia. Despite its importance and promise as a sustainable crop for smallholders in the Global South, its history remains poorly understood. Eleusine coracana has only rarely been recovered from archaeological sites in the region of Africa where it was domesticated and never in quantities large enough to study its evolution under cultivation. Here we report on a large assemblage of Iron Age (ca. 900–700 cal bp) E. coracana grains recovered from Kakapel rock shelter in western Kenya. We also carried out carbonization experiments on modern grains in order to directly compare these archaeological specimens to extant landraces. We found that finger millet is only well preserved when carbonized at temperatures lower than 220 °C, which may contribute to its scarcity in the archaeological record. Eleusine coracana shrinks but does not significantly change shape when carbonized. When corrected for the effects of carbonization, the E. coracana grown by Iron Age farmers at Kakapel was smaller grained than modern landraces, but is nonetheless identifiable as domesticated on the basis of grain shape and surface texture. A comparison with other Iron Age E. coracana reveals considerable variation in the grain size of landraces cultivated during this era. This is the largest quantitative morphometric analysis of E. coracana grains ever conducted, and provides a basis for the interpretation of other archaeological populations. This assemblage is also the first evidence for E. coracana cultivation in western Kenya, a biodiversity hotspot for landraces of this crop today.

Eleusine coracana（手指小米）是一种营养丰富且易于储存的谷物，可以在不利的环境中种植，对非洲和南亚数百万农民的粮食安全很重要。尽管其作为全球南方小农可持续作物的重要性和前景，但其历史仍知之甚少。Eleusine coracana很少从非洲地区的考古遗址中发现，在那里它被驯化，而且数量从来没有大到足以研究它在栽培下的进化。在这里，我们报告了大量铁器时代（约 900-700 cal bp）E. coracana从肯尼亚西部的 Kakapel 岩石避难所回收的谷物。我们还对现代谷物进行了碳化实验，以直接将这些考古标本与现存的地方品种进行比较。我们发现，指黍只有在低于 220 °C 的温度下碳化时才能完好保存，这可能是考古记录中其稀缺的原因之一。Eleusine coracana 会收缩，但在碳化时不会显着改变形状。当校正碳化的影响时，铁器时代农民在卡卡佩尔种植的E. coracana 的颗粒比现代地方品种小，但仍然可以根据颗粒形状和表面纹理识别为驯化的。与其他铁器时代E. coracana 的比较揭示了这一时期栽培的地方品种的颗粒大小存在相当大的差异。这是有史以来对E. coracana颗粒进行的最大的定量形态计量分析，并为其他考古种群的解释提供了基础。这种组合也是肯尼亚西部E. coracana种植的第一个证据，这是当今这种作物地方品种的生物多样性热点。