Beer is more than one of humanity’s most beloved beverages—it’s also one of its oldest. Recent archaeological discoveries date it back 13,000 years ago in the eastern Mediterranean. It was once considered so sacred that only women could brew it–until witchcraft accusations stopped that in its tracks.
[Related: Ancient poop proves that humans have always loved beer and cheese.]
The origins of our favorite types of beers are also starting to come into focus with a fun combination of history and science. A study published April 27 in the journal FEMS Yeast Research reveals a possible origin story for lager beer, a light type of beer produced by bottom-fermenting yeast. It can be pale, dark, or amber in color and pairs well with shellfish, grilled pork, and spicy foods among others.
The research team used historical records, in tandem with evolution and genomics research, and believe that lager likely originated at the court brewery–or Hofbräuhaus–of Maximilian I, the elector of Bavaria.
Lager surpassed ale as the most common beer produced around the turn of the 20th century and over 150 billion liters of lager beer are sold annually around the world. However, the shift from ale to lager started centuries before when a new yeast species Saccharomyces pastorianus or “lager yeast,” popped up in Germany around the end of the Middle Ages. The new yeast was a hybrid species that was the product of mating of top-fermenting ale yeast Saccharomyces cerevisiae and the cold-tolerant Saccharomyces eubayanus around the beginning of the 17th century.
“Lager is a beer brewed at low temperatures using yeast that are described as bottom-fermenting,” study author and University of Cork microbiologist John Morrissey wrote in The Conversation. “Yeast are single-celled fungi used in brewing to convert maltose to alcohol and carbon dioxide, giving beer its booziness and fizz. They are either top- or bottom-fermenting.”
S. pastorianus is a bottom-fermenting lager yeast, and its origins have been “shrouded in mystery and controversy,” according to Morrissey. The assumption was that the hybrid yeast arose when traditional ale fermentation became contaminated with wild yeasts. However, the team on this study doubted this historic assumption, and used detailed analysis of Central European historical brewing records to dig in more. They discovered that “lager-style” bottom fermentation was actually happening in Bavaria 200 years before the hybrid S. pastorianus yeast was born.
The team believes that it was actually the top-fermenting ale yeast S. cerevisiae that contaminated a batch of beer brewed with the cold-tolerant S. eubayanus. They believe that the source of the contaminating yeast was a wheat brewery in the small Bavarian town of Schwarzach.
[Related: The key to tastier beer might be mutant yeast—with notes of banana.]
“Bottom fermentation originated in northern Bavaria. Not only was it common practice in this part of Germany, but the Bavarian Reinheitsgebot brewing regulations of 1516 only permitted bottom fermentation. Thus, from at least the 16th century onwards, Bavarian brown beer was produced by mixtures of different bottom-fermenting yeast species known as stellhefen,” wrote Morrissey.
However, in neighboring Bohemia, excellent wheat beer made with S. cerevisiae was made in huge quantities and imported into Bavaria. To limit the blow to the economy from these imports, Bavarian ruler Wilhelm IV gave Baron Hans VI von Degenberg a special privilege to brew and sell wheat beer in the border regions to Bohemia in 1548.
Maximilian I eventually took power in 1602, and he seized the wheat beer privilege himself and took over the von Degenbergs’ Schwarzach breweries. The team believes that it was in October 1602 that the yeast from the wheat brewery was brought to the court brewery in Munich where the hybridization took place and lager yeast S. pastorianus was born.
“This theory is consistent with published genetic evidence showing that the S. cerevisiae parent of S. pastorianus was closer to ones used to brew wheat beer than strains used for barley-based ale,” wrote Morrissey.