Facilitated East-West Spread in Eurasia

Key Insight

The rapid east-west spread of food production in Eurasia is attributed to its predominant east-west axis, where localities at the same latitude share similar day lengths, seasonal variations, diseases, temperature and rainfall regimes, and habitat types. Plant germination, growth, and disease resistance are genetically adapted to specific latitude-dependent climatic features. For example, a corn plant genetically adapted to Mexico's mild climate would fail in Canada's colder conditions, either germinating too early under snow or growing too slowly to mature before autumn frosts, and lacking resistance to northern diseases.

Following its emergence before 8000 B.C. in Southwest Asia (Fertile Crescent), food production radiated rapidly west and east. This 'Fertile Crescent package'—a specific suite of plants and animals—reached Greece and the Indian subcontinent by 6500 B.C., Central Europe by 5400 B.C., and Britain by 3500 B.C., initiating agriculture in these regions. Most of these founder crops are not wild outside Southwest Asia, and genetic analysis indicates that nearly all cultivated varieties globally stem from a single domestication event for each crop. This 'preemptive domestication' suggests the crop spread so quickly that it negated the need or opportunity for independent redomestication of the same or related wild species elsewhere.

The Fertile Crescent domesticates, being well-adapted to the similar climates along the east-west axis, spread rapidly at an average rate of about 0.7 miles per year to Europe and the Indus Valley. By the time of Christ, cereals of Fertile Crescent origin were cultivated across 8000 miles from Ireland to Japan. This facilitated the diffusion of other innovations like the wheel, writing, and metalworking. Eurasia's axis also enabled the reciprocal spread of crops, such as chicken from China and potatoes from the Andes, contributing to a diverse agricultural foundation across the continent long before modern global transport.