Beer was first made by the Sumerians, and the technology was absorbed into the Babylonian and ancient Egyptian cultures. The practice of the Sumarians was to bake grains into bread, and the bread was moistened to begin the process of making beer. The baked bread was a way to preserve the grain for later use in the beer making process. A Sumerian beer was recreated recently by the folks at Anchor Steam Beer, as an experiment.
In more recent times, Louis Pasteur studied beer and wine making and patented a process for making beer which resulted in a better beer. Previously the wort was boiled and exposed to the air for cooling. In Pasteur's process, the wort is kept in closed vessels and cooled by spraying the outside of the vessel with water. A special yeast was introduced into the mash after it cooled, thus preventing contamination of the wort with stray wild yeasts floating through the air.