Final answer:
Surplus food has historically been traded for other kinds of food or goods, such as salt during early trade or commodities during the Columbian Exchange. Today, surplus food can still be traded for other kinds of food or goods using money as a medium of exchange.
Step-by-step explanation:
Surplus food has historically been traded for a variety of commodities. In the past, it was common for surplus food to be traded for other kinds of food or goods. For example, during the Columbian Exchange, commodities from both hemispheres were exchanged, resulting in increased economic opportunities and improved diets. Additionally, in early trade, salt acted as a sort of currency and was commonly exchanged for other valuable goods. Today, surplus food can still be traded for other kinds of food or traded for other goods using money as a medium of exchange.