Enlarge /. Barley grain for the production of beer in the Asahi Kanagawa brewery in Japan.
Tomohiro Ohsumi / Bloomberg / Getty Images
In recent years, archaeologists have learned a lot from the dirty dishes of old people. Microscopic residues that stick to the inside of potsherds contain chemical traces of old foods and beverages that reveal remarkable details of the diet of old people. But as far as we know now when people started eating certain grains or fermenting milk to make cheese, we're still not sure when people started brewing beer. It is difficult to distinguish a container for beer from a container in which only old grain was stored.
By looking at the remains of ancient grains under a microscope, archaeologists can determine if the grains have been malted – the first step in brewing beer.
When grains start to germinate or sprout, they release an enzyme called diastase, which converts the starch supply in the grain to sugar. The whole point of malting is that the grains release diastase, but then stop the process before the starch is converted to sugar. Once the brewer adds yeast to the malted grain, the diastase can produce more sugar to feed the yeast – and that produces carbon dioxide, alcohol, and a sweet taste. To do this, the brewers soak the kernels in water to start germinating and then stop the process by air drying the kernels and heating them in an oven.
The bioarchaeologist at the Austrian Academy of Sciences, Andreas Heiss, and his colleagues found that when barley germinated, the outer layer of the seed store was partially digested. This makes it easy to see malted barley under a microscope, as this outer layer looks unusually thin. The same applies to other grains of the grass family such as corn, rye and wheat. By searching for this thinned outer wall under a microscope, archaeologists can determine whether old grains have been malted, "even if the grains in question are only preserved as powdered and burnt crusts on ceramics," said Heiss.
It is for science – really!
To test the idea, Heiss and his colleagues malted their own barley by charring it, and then examined the results under a scanning electron microscope. They compared their freshly malted barley with 5,000 year old antique samples from Egypt and Central Europe. The results looked very similar.
Both Egyptian locations in the study were known as old breweries. Archaeologists tried charred clumps of wheat from ceramic barrels in a predynastic political center called Hierakonpolis in Upper Egypt and in Tell el-Farkha, a sand island in the eastern Nile Delta. They looked very much like the charred barley from the archaeological laboratory.
Heiss and his colleagues also examined grain residues in containers from three sea settlements in Germany and Switzerland, which were also created around 5,000 years ago. None of these three sites provided clear evidence that people were brewing beer next to the lakes, but under the Heiss and his colleagues' microscope, the kernels had the same thinned outer walls as the barley they malted in the laboratory and ancient wheat Egyptian breweries.
It is the first evidence of malted beverages or food in Neolithic Europe. Heiss called this discovery "a small side effect" of the team's research. "It was a while before we realized that we had, en passant, provided the earliest evidence of malt-based food in Central Europe."
Drinking beer at the lake
But it's still not evidence of beer. "Malt-based food" can mean many things. Brewing beer is just one reason why people could malt grain like barley; Throughout history, malted but not fermented grains have also been fed to infants who have been weaned, taken as a tonic or just eaten as a snack.
In addition, archaeologists have no way of knowing the fermentation process itself from old grains. Although malting is a very common first step in the beer and malted whiskey brewing process, you don't need malted grains to make alcohol. That said, we may still be missing a lot of old alcohol.
For the Neolithic period, which lived on Lake Constance in Germany and on Lake Zurich in Switzerland, beer makes sense. The chunks of charred grain recovered from the construction site came from cooking vessels whose shapes were not very likely to be used for cooking bread or storing sourdough. Other studies show that the water of the lake around these settlements was full of intestinal parasites. "The residents of these settlements definitely had good reasons to produce and consume beer," wrote Heiss and his colleagues.
Not all of us.
PLOS ONE, 2020 DOI: 10.1371 / journal.pone.0231696 (About DOIs).