Join Eric Pallant, chair of the Department of Environmental Science and Sustainability at Allegheny College, for a discussion about sourdough. For 6,000 years —since breads were first baked in the Fertile Crescent until the end of the 19th century — the staff of life was made by hand from only four ingredients: flour, water, salt and a sourdough culture of wild yeast and bacteria. Workers who built the Egyptian pyramids received the bulk of their calories from sourdough bread. Ancient Rome imported wheat from across its vast empire to turn into loaves it distributed to Roman citizens. Survival through the Middle Ages depended upon preparation of sourdough loaves baked in communal ovens.