A: According to “Sourdough Cookery”: The Sourdough Cookbook by Rita Davenport, sourdough has been around for 5,000 years or so. She writes, “An Egyptian noticed that some flour he had left out in the open had become wet. Bubbles had formed mysteriously in the mixture. When baked into bread, the mixture had a lighter texture and a superior, tantalizing taste. Today we know that wild airborne yeast fell into the open container of flour and water, causing fermentation. These yeasts are bacteria, similar to bacteria in sour milk or other soured foods, composed of billions of tiny microscopic plants like the organisms found in commercial yeast.” Flash forward a few thousand years. In frontier days, Davenport says,”miners and trappers carried a pot or crock of sourdough starter with them. The fresh yeast that was available at that time spoiled easily, so sourdough that could be replenished was a valued possession. Some starters became famous for their exceptionally good flavor and were passed down from generation to generation and shared with friends.”