As a commonality, rum comes from sugar cane which is one of the world's biggest crops by acreage. Originally, this grass grew in Papua New Guinea, and it was taken around the world rather quickly in order to satiate people's search for energy. Products from fermented sugar cane have an 8000 year history where little changed, but 400 years ago, things changed forever. One of the biggest changes occurred in the middle of the 16th century with the Reformation. Honey had been the main source of energy to keep up with the beeswax candles made at monasteries; however, the Reformation did away with that. Around that same time, the world got addicted to coffee and tea and it needed a new energy source. Previously, sugar came as loaf sugar and the grinding was rather inconvenient to free the sweetness from this resinous brick. Once technology advanced through boiling, rectifying, and crystalizing, pure sugar crystals that did not require any grinding step and the demand took off. What was left after the purification was molasses, the major waste product of the sugar cane industry. While the first sugar cane distillates were cachaças in the early 1600s in Brazil, 1648 was the first time rum was reported to have been made with molasses. To make sense of rum, the speakers divided it up into three different styles: the English, the French, and the Spanish (or modern) styles.
French: French people are French. Since France based its purified sugar economy on sugar beets, they disallowed the import of sugar cane. Therefore, the whole cane is juiced and fermented fresh. Moreover, this cane juice product is fermented like an eau de vie. While the ashy volcanic soil is often attributed to what makes rhum agricoles have a certain flavor, it was pointed out that St. George makes a similar rum in California on different soils. While an A.O.C. tightly regulates the style in Martinique, often they are producing the product on patchwork stills, Mad Max style.
Spanish: The history of Spanish rum can be traced back to Columbus bringing over sugar cane seeds over on his second voyage in 1493; while this batch of seeds did not succeed, 7 years later, sugar cane was growing in Hispaniola. The 1620s saw the first rum distilleries in Cuba as compared to the 1650s when rum production became an industry in Boston. The continuous still made for a cleaner rum style. Controlled fermentation, proprietary yeast, filtration, and purposeful aging and blending all aid in defining the style and regulating its purity today. Unlike the English style of age statements, the number is either the maximum age of the rum contained or solely having the style of that age. For example, Zacapa 23 Year is made mostly of 4-6 year rums but it tastes much older.
The breakfast of champions...
Finally, it was pointed out that most rum these days is made with molasses not produced on that island. Most of this molasses is imported from Venezuela and Brazil. What defines the island is the style of what they do with the molasses after they import it. Clearly, the exception is French-styled rums given the A.O.C. rules on Martinique.