The oldest written recipe in the world is a 3,800-year-old poem about how to make beer.

Archaeologists found the recipe on clay tablets in the ancient city of Nippur, which is in modern-day Iraq. The tablets date back to around 1800 BCE. The text describes making a special twice-baked barley bread called bappir. This bread acted as the main ingredient for the brew.The recipe says to mix the bread with honey and dates before soaking it in water. This mixture sat in large clay jars to ferment. The final liquid was thick and full of grain bits. Because of the floating grains, people drank the beer through long straws made of reeds.In 1989, Anchor Brewing Company worked with Dr. Solomon Katz to follow the recipe. They created a beer with 3.5% alcohol that tasted like dry cider. This experiment proved the Sumerians understood how to use yeast to change sugar into alcohol. They even paid workers with beer rations because it was so important to their daily lives.Some historians believe the desire for beer helped start the agricultural revolution. Humans may have stopped hunting and started farming specifically to grow enough grain for brewing. This makes the Ninkasi recipe one of the most important documents in human history.