In Richard Unger's Beer in the Middle Ages and the Renaissance, he points to several indications that brewers began to intuit the vital role of yeast hundred of years before Pasteur's time.

Rather than relying on wild yeast in the air, a 15th-century brewer in Munich received permission to use a specific source of yeast from the bottom of his brew.

In 16th century Norwich, England, brewers recognized the value of skimming off excess yeast for use in bread-making and further brewing.

They actually donated some of that yeast to charities.

Even without Pasteur's experiments defining the biological processes that result in living yeast turning glucose into ethanol - what he dubbed alcoholic fermentation - people evidently knew that fermentation made beer bubbly, flavorful, alcoholic, and generally much more fun to drink than plain barley water.

Beer was among the Sumerians' most influential contributions to the world, right behind written language and a formal number system.

And the Sumerians knew they had come up with something big.

They even had a goddess of beer and brewing named Ninkasi.

In the year 1800 BCE, a hymn was written for Ninkasi that doubled as a beer recipe.

Because it was written in song, the recipe was easy for the average beer drinker to memorize if they didn't know how to read.

It's also the oldest beer recipe ever discovered.

Here's an excerpt: "Ninkasi, You are the one who handles the dough with a big shovel...

You are the one who waters the malt set on the ground...

You are the one who soaks the malt in a jar, the waves rise, the waves fall...

You are the one who spreads the cooked mash on large reed mats, coolness overcomes."

If the Sumerians penned a similarly poetic cure for hangovers, it hasn't been discovered yet.

The Ancient Egyptians were also fanatical about their beer.

They believed that beer brewing knowledge was a gift from the god Osiris, and they incorporated the drink into their religious ceremonies.

It infiltrated other parts of Egyptian culture as well.

Beer was so common that the laborers who built the pyramids of Giza were given daily rations of one and third gallons, or about 10 pints of the stuff.

It was also served at celebrations, where over-imbibing was not only accepted, but encouraged.

As far as etiquette was concerned, leaving a party when you could still walk straight was the Egyptian equivalent of not finishing your meal.

Man these guys knew how to party.

But one component that's found in virtually all beer today took a while to enter the picture.

That would be hops, the ingredient that gives beer its bitter, floral taste.

Though it's more noticeable in IPAs, the vast majority of beers depend on hops to balance out their sweetness.

And hops, by the way, isn't the name of the plant; it's the name of the flower or "cone" that comes from the plant.

The plant itself is called Humulus lupulus, which means "climbing wolf" in Latin.

During the Middle Ages, Catholic monks supported themselves by selling homemade goods like cheese, mustard, and in some cases, beer.

These monks were likely the first people to make beer with hops.

In the mid-800s, a German Abbot from the monastery of Corvey in Germany referred to the use of hops in brewing.

Shout-out to YouTube commenter Timo Kramer for mentioning this abbot, Adalard of Corbie, in the comments of our last episode, sending our fact-checker down a hoppy rabbit-hole trying to pinpoint whether the reference was made from Corvey in present-day Germany or Corbie in present-day France.