When the people of the Wari Empire (predecessors of the Inca) abandoned the southern Andes around 1100 CE, they made sure nobody else could enjoy their former home by destroying the brewery that, for 400 years, had provided for lavish festivals held at the provincial center of Cerro Baúl.

"They intentionally and deliberately destroyed the site so that it couldn't be used by successor societies when they left," Field Museum Associate Curator & Professor of Anthropology Ryan Williams told Ars Technica. "The brewery itself was burned down at the end, and a great feast accompanied that burning, in which the special ceramic vessels from which the local lords would have been served were smashed into the burning flames."

The smashed pots that were left behind, however, contained clues to the ancient beer recipe that once held an empire together.

Lasers and broken pottery

The fermented drink called chicha is still an important part of social life in the Andes, but a thousand years ago, it lubricated the very machinery of empire. Feasts at provincial centers like Cerro Baúl helped the Wari hold together an empire that spanned over 1,300km (808 mils) along the Andes Mountains. Members of the social and political elite from neighboring provinces (and, according to the different styles of some of the ceremonial drinking mugs at Cerro Baúl, sometimes from far away, too) converged on the mountaintop settlement to bring tribute to the imperial government, feast on llama and seafood, and drink chicha.

The drinking wasn't just a social lubricant: drinking toasts to visitors and deities was an important part of the ritual. Williams, University of North Carolina Greensboro Associate Professor of Anthropology Donna Nash, and their colleagues say they hope to better understand the big picture of how the Wari maintained unity across an empire linked only by pedestrian traffic across the mountains.

One piece of that puzzle, Prof. Williams told Ars, is the small-scale process of making chicha for state feasts. To understand it, the archaeologists analyzed broken pots from Cerro Baúl's brewery using laser ablation mass spectrometry (proper scientific jargon for very carefully shooting the potsherds with lasers and measuring what pops loose). "The laser drills a very small—almost invisible to the naked eye—hole in the ceramic vessel, which creates a small dust, and it's carried on this aerosol into a mass spectrometer," explained Williams.

Inside the mass spectrometer, the sample is heated to about 9,000⁰C, which is hot enough to break down the bonds that hold molecules together. This leaves charged atoms, which get sorted by mass.

"That molecular scale gives us insight into the process by which the beer was produced. The insights into that process then tell us about the individuals who were making the beer and the choices that they were making," Williams told Ars Technica. "Every large-scale action taken in sociopolitical terms actually does break down to individual actions and individual decisions. It's the actions of the individual agents like that who create the institutions in our society that are so important to binding us together in these big multicultural groups."

Field Museum

Field Museum

An old family recipe

It turned out that the organic molecules still clinging to the insides of the broken pots had come from pepper berries, or moye. If you've ever bought a pepper grinder with multicolored peppercorns, you've actually eaten moye. The pink peppercorns come from the center of a hard sugary resin, wrapped up in a papery pink peel. That sugary resin is the stuff that goes into moye chicha, which Prof. Nash describes as a little like mead.

Pepper berries are the perfect choice for chicha brewers who need a reliable, year-round source of material that can be brewed up in a hurry. If you're an empire trying to put on an impressive show of power for provincial elites and earn their goodwill at the same time, you can't afford to run short of booze because your maize crops had a rough year.

Moye trees are more drought-resistant than other traditional chicha ingredients, like corn. In fact, with careful planning, the Wari could have ensured a nearly year-round supply of fresh pepper berries to make chicha for festivals. "Different moye trees are in bloom at different times, so if you were really careful, you can manage the trees so that you have sufficient batches available all the time. But it would require management," Nash told Ars Technica.

Chicha is still a part of modern life in Peru, but it's seldom made in the traditional way anymore. Most people use aluminum pots on gas stovetops, not ceramic pots over open fires. But Nash and her colleagues wanted to know more about how Wari brewers would have prepared chicha. Fortunately, a member of Nash's local excavation crew had an aunt in a remote village who still brewed old-school moye chicha, and she evidently didn't mind showing a group of archaeologists how it was done.

To make moye chicha, brewers steep the pepper berries in boiling water for about 10 minutes to melt the resin, then strain out the peppercorns and let the melted resin ferment for about five days. That's about half the time—and about half the effort—it takes to make the corn version, which must have been an advantage for ancient brewers rushing to prepare for a big feast.

Women at work

And the work, vital to Wari politics, was in the hands of women. Most modern chicha brewers are women, like the excavation crew member's aunt. And the tradition stretches back at least as far as the Inca, who sent the daughters of noble families to something like finishing schools to learn weaving, chicha brewing, and the skills needed to prepare ritual feasts.

"There would have been several hundred girls cloistered in these facilities and being trained," Nash told Ars Technica. "When they were about 14 or 15, they would be married off or selected to enter priestesshood, and a few probably ended up as sacrifice victims."

We don't know if the Wari trained their upper-crust girls in similar schools, but artifacts found in the brewery at Cerro Baúl suggest the presence of women at work. Among the ruins, archaeologists unearthed shawl pins and hair pins in styles usually found buried with Wari women, but they also found spindles, which reveal a bit about the women's working lives.

"While they were watching the chicha boil or stirring it, they would have also been using a drop spindle to create very fine thread," Nash told Ars Technica. That thread may have gone into weaving fine, gauzy cotton cloths for straining the dregs from the chicha.

Sustainability, 2019. DOI: 10.3390/su11082333; (About DOIs).