Answer:
When people began to grow crops and domesticate animals
Explanation:
The cultivation and domestication of animals were the first signs of the process of accumulation observed in primitive societies. Accumulation, in turn, gave rise to the surplus - when output was greater than the needs of the producer - and encouraged men to exchange their respective surpluses. Thus came the first evidence of economic development. When societies became a bit more complex, the need arose for the creation of currency to facilitate the exchange of surpluses.
