Cows have lots of stomachs. You would too if you ate grass all day. One of those stomachs is actually a rumen, a special digestive organ that allows them to regurgitate and remasticate their food. For this reason, cows and animals like them are called ruminants. Sheep, deer, and even giraffes all swallow their food, only to spit it back up out of their special rumen stomachs to be chewed again. They can chew and swallow the same food 50-70 times before it passes to the next stomach for more traditional digestion (ruminantdigestivesystem.com). In doing this, the animals break down the fiber of their rough food sources with mechanical and chemical digestion. Once the fibers in grass or leaves are broken down, they will ferment in the rumen with the help of a diverse microbial population that make more biologically useful compounds which the animals can use as energy. In this process, the animal creates volatile fatty acids for energy and burps out the by-product gases produced during fermentation (ruminantdigestivesystem.com). Unexpectedly, this process is remarkably similar to the earliest human efforts to make booze out of complex starches.

These animals chew to survive and rely on fermentation to produce their energy. If we tweak this process slightly, we arrive at some of the earliest human forays into fermenting complex starches as well. We chewed to brew. In the human context, the rumen organ becomes an earthen vat,  the microbial population is airborne yeast, and the end product is alcohol. Humans chewed (some still do) cereals and other starches repetitively and spit them into communal vats where salivary amylase could perform saccharification and thus enable fermentation to occur. Starches must be broken down into simple sugars for yeast to digest them into alcohol and carbon dioxide. It just so happens that our saliva can make that happen. 

In Brazil, traditional beverages known generally as cauim (pronounced kawi) are made from a wide range of source materials including cassava, pumpkin, cotton seeds, and corn (Ramos). The drink is a nutritional staple and is typically consumed in a non-alcoholic form. During harvest season, a time of celebration, the drink is fermented. Women oversee this process and stimulate the fermentation by providing the source yeast and bacteria. They do this by chewing sweet potato and spitting the pulp into the boiled vat of non-alcoholic cauim (Ramos). The mixture is fermented in an open vat for 1-2 days. The chewing provides the microculture or yeast and bacteria necessary to trigger this fermentation and help break down complex molecules into simple sugars.