The map above shows how four of the world’s most important domesticated cereals spread across Europe, Asia and Africa between 7,000 and 3,500 years ago.
Liu’s study traces the farm-to-table journeys of mainstay cereal crops as they criss-crossed continents of the Old World in three distinct waves:
Before 5000 B.C., early farming communities sprang up in isolated pockets of fertile foothills and stream drainage basins where conditions were optimal for cultivating wild grains that originated nearby. Crop dispersals are generally limited to neighboring regions that are broadly compatible in terms of climate and seasonality.
Between 5000 and 2500 B.C., farmers found ways to push cultivation of various grains across wide regions where crop-compatible weather systems were contained within and separated by major mountain systems, such as those associated with the Tibetan Plateau and the Tianshan Mountains.
Between 2500 and 1500 B.C., farmers found ways to move beyond natural and climatic barriers that had long separated east and west, north and south — mastering the cultivation of grains that had evolved to flourish in the extreme elevations of the Tibetan Plateau or the drenching rains of Asian monsoons. Previously isolated agricultural systems were brought together, ushering in a new kind of agriculture in which the planting of both local and exotic crops enables multiple cropping and extended growing seasons.
One very noticeable missing piece is the spread of corn/maize which originated in the Americas. Yet it is the third most important type of cereal after wheat and rice.