Maize (Zea mays)

node · earth · Mesoamerican origin; global by transfer

Domesticated in Mesoamerica from the wild grass teosinte and the New World crop that spread furthest and fastest after 1492. Maize travelled east on the first return voyages and was being grown around the Mediterranean within decades; it reached West Africa through Portuguese contact and China by the middle of the sixteenth century, where local gazetteers record it well before any European traveller described it. Its appeal was the same everywhere: a high yield per hectare, a short season, tolerance of ground unsuited to rice or wheat, and cultivation on hill slopes that could be brought into production without displacing existing staples — which is why in China it is associated with the settlement of upland interiors rather than with the rice plains. Maize also carries a hidden cost that took four centuries to identify. Its niacin is chemically bound and unavailable unless the grain is treated with alkali, as Mesoamerican nixtamalisation does; populations that adopted the crop without the processing developed pellagra, an entirely avoidable deficiency disease that killed for generations in southern Europe and the American South.