Did the hunt for spices really cause the age of exploration?

Spices were a major motive, but not the only one, and the most popular version of the story gets the timing wrong. That version says the Ottomans closed the spice route when they took Constantinople in 1453, so Europe had to sail around Africa. Yet Portugal's voyages were well under way by then. Under Prince Henry the Navigator, systematic sailing down the African coast started in 1421, one of his captains finally passed the difficult Cape Bojador in 1434, and Senegal and the Cape Verde Peninsula were reached in 1445. The fall of Constantinople was a perceived blow to Christendom and to established business links with the East, but the ships had set out long before.

A blocked route did not automatically mean dearer spices either. When wars and banditry closed the overland routes into Asia as the Mongol states broke up, trade from India went almost entirely into the Red Sea, and European spices did not become more expensive as a result.

What was true is that the old trade was a monopoly. From the 8th to the 15th century Venice and neighbouring maritime republics held the monopoly of European trade with the Middle East, and the silk and spice trade made them phenomenally rich. Pepper's exorbitant price and Venice's monopoly helped motivate the Portuguese to seek a sea route to India. In 1498 Vasco da Gama's representative, asked in Calicut why they had come, replied "we seek Christians and spices".

That reply points to the other motives. Religion played a critical role in motivating European expansionism. Henry hoped to bypass Muslim territories, find Christian allies such as the supposed kingdom of Prester John, and probe whether the Indies, the source of the lucrative spice trade, could be reached by sea. There was also a money problem: Europeans had a constant deficit in silver and gold, as it only went out, spent on eastern trade.

So spices were one strand among several. They gave the voyages a goal, while the search for Christian allies and for a way round Muslim and Venetian middlemen gave them more reasons to go.