1992: Scientists report evidence in the journal *Nature *of ancient beer in a 5,000-year-old jug at Godin Tepe in the central Zagros Mountains of Iran. It's the earliest trace of beer ever discovered.

Researchers just the previous year had confirmed evidence of wine from around the same time at the same site, which became a fortress on the Silk Road. But later texts from the area suggest beer was the more popular beverage in lower Mesopotamia and was drunk by common folk as well as the upper class.

The discovery of residue from beer-brewing in the interior grooves of a jug from the site supported the idea that beer was the preferred fermented beverage among the Sumerians.

The yellowish substance found in the grooves of the jug, which was in the Royal Ontario Collection, proved to be calcium oxalate, also known as beerstone, a common byproduct of brewing with barley.

To confirm that it was beerstone, the scientists compared the chemical composition to residue scraped from the inside of a brew kettle at Philadelphia's Dock Street Brewery, as well as to scrapings from an ancient beer vessel from the museum's Egyptian New Kingdom collection.

The grooves may have been intended to collect the beerstone, which can be very bitter and even poisonous, and keep it from ruining the beer. And early Sumerian symbols for beer jugs have similar crisscross markings on them.

Further possible evidence of beer: The floor of the supply room where the jug was found had barley on it, likely grown locally and used in the brewing.

It's unclear what type of beer was in the jug, but it is known that residents of Mesopotamia enjoyed many different varieties including light, dark, amber, sweet and specially filtered beers.

Source: Various

Images: 1) Tambako The Jaguar/Flickr

2) Modern beer kettle. GoatLegSF/Flickr