premise: The history of bread and cake starts with Neolithic cooks and marches through time according to ingredient availability, advances in technology, economic conditions, socio- cultural influences, legal rights (Medieval guilds), and evolving taste. The earliest breads were unleavened. Variations in grain, thickness, shape, and texture varied from culture to culture. Archaelogical evidence confirms yeast (both as leavening agent and for brewing ale) was used in Egypt as early as 4000 B. C. Food historians generally cite this date for the discovery of leavened bread and genesis of the brewing industry. There is an alternate theory regarding the invention of brewing. Some historians believe it is possible that brewing began when the first cereal crops were domesticated. Sources generally agree the discovery of the powers of yeast was accidental. "No one has yet managed to date the origins of beer with any precision, and it is probably an impossible task. Indeed, there are scholars who have theorized that a taste for ale prompted the beginning of agriculture, in which case humans have been brewing for some 10,000 years... Most archaeological evidence, however, suggests that fermentation was being used in one manner or another by around 4000 to 3500 B. C. Some of this evidence-from an ancient Mesopotamian trading outpost called Godin Tepe in present-day Iran- indicates that barley was being fermented at that location around 3500 B. C. Additional evidence recovered at Hacinegi Tepe (a similar site in southern Turkey) also suggest that ancient Mesopotamians were fermenting barley at a very early date.
hypothesis: It can be assumed that yeast was discovered accidentally.