Lager history

I'm really sure why anyone thinks it's important to work this out, but I guess it's interesting nonetheless.

From Science:

If you like lager, chances are you’ve got a 17th century brewmaster to thank for it. The commercial yeast used to brew most modern lagers was created when the pasty yeast slurries for a white ale and a brown beer mixed in a cellar of  the original Munich Hofbräuhaus—not to be confused with the beer hall there today—sometime between 1602 and 1615, according to a new synthesis of historical brewing records and genetic histories of yeast.

Today lager accounts for 90% of all beer sold; ales, made with different yeasts, make up the rest. Nonetheless, the origin of lager has been “shrouded in mystery for many years,” says yeast biotechnologist John Morrisey of University College Cork. The Hofbräuhaus scenario is “definitely plausible,” says evolutionary biologist Brigida Gallone of Naturalis Biodiversity Center, who was co-author of a key genetics study.

Although 17th century brewmasters didn’t know about the existence of yeast, they did notice the new blend was a winner—it fermented vigorously like an ale but tolerated colder temperatures, like a brown beer. This meant they could brew a clean-tasting lager earlier in the spring in the Northern Hemisphere, where temperatures plummeted during the Little Ice Age, from about 1300 to 1850 C.E. Eventually, one yeasty starter from the new brew was taken by stagecoach to Copenhagen, Denmark. There, in 1883, Emil Christian Hansen, a mycologist at the Carlsberg Research Laboratory, purified this hybrid yeast, named Saccharomyces pastorianus in honor of the French chemist Louis Pasteur.

Hansen’s purified strain revolutionized beer production because brewers could consistently make high-quality, safe lager from every batch. Before that, wild strains of yeast sometimes contaminated the slurries, causing “beer sickness” and gastrointestinal distress. The purified version of S. pastorianus was so successful that it quickly replaced older yeast strains and is still used in most lagers today.