It is tempting to think of this as a kind of global lightbulb moment, but that is really stretching things. Most of the developments actually involved vast periods of trial, error, and adjustment, often over the course of thousands of years. Agriculture started 11,500 years ago in the Levant, but 8,000 years ago in China and only a little over 5,000 years ago in most of the Americas. People had been living with domesticated animals for 4,000 years before it occurred to anyone to put the bigger of them to work pulling plows; Westerners used a clumsy, heavy, exceedingly inefficient
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