Beer (n.). A mildly alcoholic beverage invented by adult male humans in historical times when they got tired of eating moldy bread.
Beer yeast is closely related to bread yeast, indeed bread yeasts are a narrower family, suggesting that beer came before bread. This would put beer back to before the invention of agriculture, making it an integral part of human society for perhaps a million years. Certainly that explains how proto-human females would accept male partners who did not wash, shave, or play the sax. Making beer from grain is simple enough. One allows the grains to sprout, then one roasts and crushes them, and adds this to the beer pot, with water. One waits a few days, one drinks. It is very important to keep the yeast colony alive and healthy over generations. Otherwise the only way to get fermentation started is to chew up the grain and spit it back into the beer pot. Next time you sneer at a Bud Light, reflect that it's less disgusting than grandmother spit.
Beer is of course not the only form of alcohol. We have been fermenting and distilling every possible form of starch, for ever. Alcohol is such a fundamental social enabler and safety valve that societies can be classed into those that depend on significant volumes of alcohol, and those that are collectively crazy. Modern industrial production has created a widespread alcoholism problem.