We wrote last month that cheap commodities underpinned economic growth for much of the 20th century but that situation has changed dramatically over the past decade. By the year 2000, the world had become accustomed to relatively low international food prices when price inflation-adjusted food commodities were below those recorded during the Great Depression. However, over just eight years, the prices of commodities have risen to levels not seen since the early 1900s. The past decade has also coincided with a big rise in speculation in commodities including food and whether it's the Arab Spring or French Revolution, big spikes in food prices can trigger dramatic social and political changes.