Why are foreign exchange rates

An exchange rate is how much of your country's currency buys another foreign currency. For some countries, exchange rates constantly change, while others use a fixed exchange rate. The economic and social outlook of a country will influence its currency exchange rate compared to other countries.

Explanation:

they can increase to boost the enonomy.

it depends on which society you are referring to. many civilization performed rituals so the gods would with their growing season but the most well known is that of the aztecs. they would make sacrifices, usually animals, but sometimes humans as well.