Résumé
The Niger River is second only to the Nile in length in Africa, and is host to dense populations of agriculturalists that supported in historical times states such as the kingdoms of Songhay and Mali. This is also the region to which the origin of the Niger-Congo language family, including its Bantu offshoot is attributed. Despite this, archaeobotanical evidence for the development of Agricultural systems based on both ancient West African crops, like Pennisetum glaucum (L.) R. Br., Vigna unguiculata (L.) Walp. and Oryza glaberrima Steud., and crops introduced to the Niger Basin, such as Sorghumbicolor (L.) Moench. and Gossypium L. sp. has remained limited. In particular the role of multiple crop systems, that included both the wet (rice) and the dry (millets), has not been directly documented archaeobotanically. The present paper presents new archaeobotanical results from 12 sites in Benin that suggest that the rise of larger populations and population centers, like the urban site of Birnin Lafiya, developed only once Agriculture diversified beyond Pearl millet cultivation to include multiple cereals, as wet rice. The 12 sites are split in four time periods. Flotation results indicate that sites of the first phase (first millennium BC) were dominated by Pearl millet, but included Sorghum and cowpea. However by the second period (300–900 AD), rice dominated samples, correlated with increasing Urbanism, a pattern congruent with existing evidence from Mali. In addition, we report evidence that probable fonio (Digitaria cf. exilis (Kippist) Staph.) also appeared first in this era of diversification, calling into question previous inferences about the Antiquity of these West African millets. The third phase, 900–1400 AD, is characterized by an increase of Pearl millet and a decrease of African rice. During the last time period, 1400–1950 BC, we notice a disappearance of rice and a diminution of Pearl millet and Sorghum. Also, the utilizations of tree fruit such as baobab (Adansonia digitata L.), Oil palm (Elaeis guineensis Jacq.), and African olive (Canarium schweinfurthii Engl.) are in constant evolution since the second period. We conclude that agricultural diversification helped to promote urbanization and state formation in the Niger River basin, and that diversification included both use of wetter environments for rice and more marginal dry environments for millet and Sorghum.