Beer is almost as old as civilization itself. Some historians believe that beer making started some 10 millenniums ago when our ancient ancestors moved away from hunting and gathering, and started agriculture. Nobody really knows how it was invented, but the common belief is that a barrel of bread or grain got wet and turned into pulp. Someone must have tried this pulp, either out of curiosity or hunger, and found it good. Majority of the ancient civilizations, like the Mesopotamians and the Egyptians, included the drink in many of their religious ceremonies.
One has to wonder, however, if the beer made today is still the same as the ancient beer that our ancestors created. The answer is no. While the brewing process and techniques remain largely unchanged, the home brewing supplies back then were different.