Diseases cross over from animals
Living beside livestock in dense settlements creates the human infectious diseases.
- When
- —
- Duration
- 4.7 thousand years
- Known to
- ± 1 thousand years
- Era
- Neolithic, Holocene
Measles, smallpox, influenza, tuberculosis and many others derive from pathogens of domestic animals, and they require dense populations to persist — a crowd disease burns out in a band of thirty foragers. Farming supplies both conditions at once: constant close contact with herds, and settlements big enough to sustain chains of transmission. The result is the epidemiological world humans have lived in ever since, and eventually the decisive weapon in the conquest of the Americas.