Résumé
Manioc (Manihot esculenta, Euphorbiaceae) is among the earliest plants domesticated in Amazonia and has long played important roles in food production systems in lowland South America. Studies from archaeology, ethnobiology, ecology and genetics have shed light on the early domestication of manioc, the traits that the plant evolved under domestication, the coevolution between these traits and the practices of cultivators, and how this coevolution has contributed to shaping the organization of manioc-cultivating societies. This research shows that the domestication of manioc was embedded in a broader context of landscape management and that domestication processes involved the complex interplay of conscious and unconscious human selection and natural selection in cultivated environments. The plant’s reproduction is only partly controlled by humans. Cultivators propagate the plant vegetatively, planting stem cuttings of selected clones. However, native Amazonians also incorporate volunteer seedlings, issued from the plant’s uncontrolled and highly outcrossed sexual reproduction, as new clones. This incorporation is highly selective, and these plants are also subjected to intense natural selection in complex managed landscapes. The selective incorporation of sexually produced seedlings is widely distributed among linguistic groups. This wide distribution, and several traits of the plant’s domestication syndrome, suggest that the practice is an ancient feature of manioc cultivation. Manioc landraces show great variation in their content of cyanogenic glucosides, a trait shaped by both cultural and natural selection. Bitter landraces with high cyanogen content require time-consuming processing, with important implications for the organization of societies that specialize in cultivation of bitter manioc.