The area of origin ofManihot esculenta as a crop plant—a review of the evidence

Conclusion

It has been suggested by Mangelsdorf and his co-workers (1964) that the two subdivisions (according to toxicity) into which cultivated manioc falls “had a separate and local history of cultivation,” and an examination of the evidence presented above makes it possible to elaborate on this suggestion.

It may be proposed that sweet manioc was first domesticated in Mesoamerica as one item in an assemblage of vegetatively propagated crops. Although suit-able progenitors representing the full range between sweet and bitter manioc may have been available, there is no evidence to indicate that bitter manioc was utilised in Mesoamerica at an early date, and early historical sources only record the use of the less poisonous varieties. When only the sweet varieties occur, they characteristically form part of a crop complex dominated by maize, and sweet manioc may have been spread with maize by the human migrations that penetrated into South America. Bitter manioc, on the other hand, is likely to have first come under cultivation in northern South America and to have achieved great prominence as the major crop in horticultural systems depending mainly on vegetatively propagated crops. Recovery of clay griddles from archaeological sites and the distribution of associated characteristic painted pottery types suggest that this process may have been initiated in the interior of Venezuela, with later migrations towards the coast via the Orinoco (Rouse & Cruxent, 1963). Subsequent intercommunication between, and migration of, Amerindian tribes has evidently caused both types of manioc to diffuse widely and to become established as crops of major importance. In Brazil, where there is considerable varietal diversity and an abundance of relatedManihot species, there must have been particularly favourable conditions for hybridisation and the development of new varieties of manioc; but on present evidence it seems unlikely that bitter manioc was first domesticated there.