I have had Spice: The History of a Temptation, by Jack Turner, on my pile to read for some time now, but never got too far in it because the type is fairly small and my eyes are at that 40-something stage where I should use reading classes but can often avoid it. Finally, I surrendered to the glasses and picked up the book. It was worth it. The subtitle is appropriate, because rather than write a comprehensive history of spices, Turner focuses on the period in European history when spices had the strongest impact: the Middle Ages, when food was noticeably full of spices, and the Age of Exploration, when Europe north of Italy entered the spice trade. The book could use a map to clarify all the geographic terms, and the chronology gets a little confusing, because he treats the various appeals of spices seperately, but other than that, it is well written and fun to read.
Turner starts his review of spices' temptation with the obvious: money. In the fifteenth and early sixteenth centuries, Spain and Portugal worked hard to find new routes to the Indies because they wanted a cut of the spice trade and the stunning profits to be made in it. Portugal was more successful with spices and ruled India until the Dutch came in a century later and out-ruthlessed them. Eventually, in 1770, the French stole some clove and nutmeg plants from the Dutch spice islands and planted them on French islands in the Indian Occean; it took several years for the plants to bear fruit, but the proliferation of spice plants through the French and English colonies was well started - as was the decline of spices' cachet.
But why were spices worth so much money to Portugal? The obvious use, to us, is for seasoning food. Medieval recipes are full of spices in combinations that look odd to us now; they mix sweet with savoury, and include cinnamon, cloves, and ginger in all kinds of meat, from fish to fowl to venison. Although this was the preferred taste of the time, Turner points out that these recipes were primarily for feasts or special occasions, and that many of the spiciest were probably an attempt to add lighten the monotony of long fast periods such as Lent, when no meat (only fish) was allowed. Spices were also used profligately because they were a sign of status, the age's preferred form of conspicuous consumption.
But spices had other uses that increased demand. Most perfumes were based on spices, especially cinnamon oil. Medieval doctors had very few medicines available to them, and spices had all the right attributes: they were exotic, expensive, and flavorful; not surprisingly, spices made up the bulk of many cures, sometimes in combinations that seem useful only because taking them would be so awful that getting better would beat taking another dose. Spices were popular among men for more lascivious uses because they were believed to heat the blood; churchmen railed against them for the same reason. Spices also had religious uses, from burning incense during Mass to embalming the bodies of kings for the journey back to the burial site (the best option before embalming was developed). These non-food uses, all benefitting from spices' exotic nature, probably overshadowed food uses until late in the Middle Ages.
Just as I was finishing the book, I read The Spices of Life in the March 2008 edition of ODE, which brings the medical uses of spices up to date. Scientists are finding that some spices do have medical benefits, although generally not the same ones that medieval doctors atrributed to them, and that more research is worthwhile. Turmeric is an anti-inflamatory and antioxident, and may be useful in treating cancer and Alzheimer's. (I added turmeric to the rice for dinner last night, and it was tasty as well as colorful.) Saffron shows some promise in alleviating depression. Chili peppers may reduce cancer. Ginger, long used for nausea, can help with morning sickness and may be useful in treating high blood pressure, diabetes, arthritis, and radiation sickness. All the spices have fewer side effects than most currently available drugs, making them even more desirable medically. So it looks like spices are still useful for more than just enlivening dinner.