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The Means of the Stone Age: Hot Rocks in Ancient Brewing

Mashing with hot rocks isn’t just an antiquated quirk of a few farmhouse brewers. In fact, we may be able to blame the technique for the founding of human civilization.

Joe Stange Apr 19, 2022 - 4 min read

The Means of the Stone Age: Hot Rocks in Ancient Brewing Primary Image

Stones used for a mash by a brewer in Latvia. Photo: Lars Marius Garshol

For some reason, whenever I imagine ancient peoples anywhere making the earliest beers, I always imagine them huddled around a big cast-iron cauldron over a blazing fire.

That image is wrong, though. There were no metal kettles for direct-fire cooking until the Bronze Age, perhaps 2000 BCE. Then, for long after—at least until the 16th century—kettles remained expensive and rare for common people.

Yet, they brewed.

As Lars Marius Garshol notes in Historical Brewing Techniques—and as numerous raw-ale traditions should make obvious—you don’t need to boil wort to make beer. You do, however, need to heat the mash. And if you’ve got a fire and some rocks, you’ve got a pretty obvious way to go about it. (For more about this old technique, see Fire & Brew-Stone: The Real Story of Steinbier.)

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“Every conceivable variation in brewing process has been used together with hot stones, including varying the grain type and other ingredients,” Garshol writes. “So, it does not really make sense to talk about stone beer as a single style. Stone beer was probably the main branch of beer styles right up until the end of the Middle Ages.”

In fact, Europe is apparently littered with deposits of fire-cracked stones that may have been used for that very purpose.

“Yes, kettles were expensive from the Iron Age on and later,” says Merryn Dineley, a British archaeologist who specializes in ancient technology—especially in methods and devices related to brewing and malting. “So, hot stones were used traditionally when the mash tun was wooden. However, the technique goes way back into prehistory. Stones have been found in limestone troughs at a site dated to 13,000 years or so ago.”

Those stones are at Göbekli Tepe, an early Neolithic archeological site in southeast Turkey, not far from the Syrian border. It is one of the world’s earliest known human settlements. The roughly 40-gallon troughs there contain a residue that would match that left behind by brewing beer—which, some hypothesize, might be why those people decided to settle down in the first place.

While not conclusive, it supports the theory that beer was an important motivator for people to stop roaming and grow crops.

Reports on such findings often refer to evidence of “cereals.” However, as Dineley says, cereals are not enough to make beer—those cereals need to be malted; those sugars need to be converted before yeast can ferment them. In fact, that desire to make malt and malt sugars—not only a source of beer, but of valuable calories—might have been the real reason to settle down and grow grains in the grasslands. As Dineley notes, there is evidence of malting about 13,000 years ago in Israel’s Raqefet Cave.

“The question,” she writes, “should not be ‘Bread or beer?’ but, ‘Who were the first maltsters?’”

So, in fact, those scattered farmhouse brewers still using hot stones to heat their mashes in the Baltics, Finland, and Russia may be carrying on a technique that is at the very root of civilization.

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