Professor Li Liu examining ancient starch grains. Credit: L.A. Cicero.

Archaeologists at Stanford University have analyzed residues from 13,000-year-old stone mortars found in the Raqefet Cave, a Natufian graveyard site located near Haifa, Israel. Remarkably, the results suggest that the residues are the byproduct of ancient beer-brewing operations. Judging from the timeline, the discovery means that humans had been brewing beer long before they were baking bread, or cultivating cereals for that matter.

“This accounts for the oldest record of man-made alcohol in the world,” said Li Liu, a professor of Chinese archaeology at Stanford.

Agriculture ushered in a new age in the timeline of human evolution. With a stable supply of food and a permanent roof over their heads, humans were free to engage in other pursuits, such as brewing beer. However, the ancient residues retrieved from the cave in Israel — which include starch and microscopic plant particles known as phytolith, typically encountered in the transformation of wheat and barley to booze — paint a totally different history.

“This discovery indicates that making alcohol was not necessarily a result of agricultural surplus production, but it was developed for ritual purposes and spiritual needs, at least to some extent, prior to agriculture,” Liu said.

Liu and colleague were not looking for traces of alcohol. Instead, they were trying to piece together what the diets of the local people who inhabited the ancient cave looked like. The oldest evidence of bread making comes from another Natufian site in east Jordan, estimated to be 11,600 to 14,600 years old. But the beer-brewing evidence reported in the new study could be from 11,700 to 13,700 years old.

Previously, the team investigated 5,000-year-old beer-brewing tools in China, the earliest such tools found in that part of the world. Both the ancient Chinese and Natufian beers looked and tasted radically different from the modern variety. Natufian beer, for instance, probably resembled porridge or thin gruel, said Jiajing Wang, co-author of the new study and a doctoral student in the Department of East Asian Languages and Cultures at Stanford.

The team believes that the Natufians employed a three-stage brewing process. In the first step, starch of wheat or barley would have been turned into malt by germinating the grains in water, before draining, drying, and storing them. In the second step, the malt would be mashed and heated. Finally, the whole concoction would be left to ferment with airborne, wild yeast.

Microscopic traces of ancient starches extracted from the Raqefet Cave (left) are compared to starches replicated in the lab. Credit: Courtesy Li Liu.

To test their hypothesis, the researchers recreated each of the steps that the Natufians might have taken to brew their beer. The team then compared their starch, which changed during the brewing process, to the ancient variety that the scientists had discovered in the cave in Israel. The results show very clear similarities. What’s more, the ancient stone mortar had similar wear and markings as the equipment used in the lab to pound and crush grain seeds.

The findings suggest ancient brewing was an important part of Natufian rituals, whose culture incorporated fairly sophisticated technological innovations and social hierarchies. In time, beer brewing achieved ‘mainstream’ status as grain became more available following the advent of agriculture. It’s funny to contemplate, nevertheless, that beer precedes bread and, in some cultures, may have been the primary motivator to cultivate cereals.

The findings appeared in the Journal of Archaeological Science: Reports.