ABSTRACT
The emergence of cassava as a global crop Doyle McKey, University of Montpellier, France; and Marc Delêtre, Trinity College Dublin, Ireland
1 Introduction
2 Origins and early cultivation of cassava in the Americas
3 Introduction of cassava in the Old World
4 Conclusion
5 Where to look for further information
6 Acknowledgements
7 References
Among tropical crops, cassava1 is unique in its ability to produce economically viable yields with little input of materials and labour, even in marginal ecological conditions (McKey and Beckerman, 1993; Burns et al., 2010), and plays a crucial role in efforts to achieve food security in the tropics. We trace the origins of cassava as a crop, focusing on the coevolution of the key adaptations – biological adaptations of the plant and cultural adaptations of its cultivators – that led to cassava’s success and its diffusion throughout the Neotropics. We then trace the diffusion and early cultivation of cassava in areas where it was introduced following the Columbian exchange. In these areas, cassava diffusion was often accompanied by a process of cultural reappropriation that we consider to be a form of ‘cultural domestication’. This complicated plant – the world’s only staple crop that can be dangerously toxic if not correctly prepared – was introduced by Europeans throughout the tropical world, but without the Amerindian folk knowledge with which it had coevolved. We identify two key co-adaptations of the crop and the native Amazonians who shepherded its domestication and diffusion throughout the Neotropics: (1) a mixed clonal/sexual reproductive system, resulting from the match between the plant’s traits and cultivators’ use of space over time, and (2) built-in chemical defences against herbivores and pathogens and practices to manage these defences safely. Neither of these themes has received the attention they both deserve from cassava breeders, agronomists and other stakeholders engaged in designing paths to food security. We discuss examples where initial mismatches between the plant’s ecological traits and farming practices were partly overcome by farmers’ ingenuity, which
led to many technical innovations. Although socio-economic conditions, farming practices, even the plant itself, have all changed in myriad ways since the crop’s domestication, some things are timeless. As we try to design a sustainable future in a changing world, cassava will likely play an ever more prominent role as other crops fail (Brown et al., 2016), and it may be wise to draw some lessons from the past.
