Vectored from Current Biology via Ed’s Beer Site:
It has been clear that the lager yeast is a hybrid with one portion of its genome having originated from S. cerevisiae ale yeast [2] . However, the source of the non-ale subgenome, which endows lager yeast with cold tolerance, had been a matter of debate [3] . Recently, a Patagonian origin hypothesis of lager yeast has been proposed based on the discovery of a new cryotolerant Saccharomyces species from Patagonian native forests of Argentina [4] . This yeast, named S. eubayanus, exhibited the closest known match (99.56%) to the non-ale portion of lager yeast and, thus, was believed to be its progenitor. However, we now show that this yeast species is likely native to the Tibetan Plateau. One of the Tibetan populations of the species exhibits closer affinity with lager yeast than the Patagonian population as inferred from population genetics and genome sequence analyses. We thus provide strong evidence for a Far East Asian origin hypothesis of lager yeast, which apparently corresponds better with geography and world trade history.
Pretty cool – and much more intuitive than a Patagonian origin, what with the aforementioned geography and history (maybe it traveled via a horsehide bagful of kumis strapped to some Mongolian saddle?), and also what with China as a possible origination point for the Saccharomyces species.
Hardly scientific, but Tibetan monks and bock-brewing Franciscans in the Alps make a pleasing kind of cultural symmetry. Plus: yetis.
the beer engine 
May I posit an alternative hypothesis? What does Patagonia, Tibet and Franciscan monks have in common? Mountains! Perhaps S. eubayanus is ubiquitous to mountainous regions across the globe.
Oops! Replace what does with what do.
Yep! That would help explain the innate cold-tolerance.
I lived in Mongolia for two years way back in ’91 as a Peace Corps volunteer and witnessed a fair amount of ayrak production (fermented mare’s milk). I consumed a fair amount of it as well. When it was fresh it was fabulous. I wish I could have taken notes or photos because all I remember was a goat hide or horsehide bag that was occasionally beaten with a stick to rouse it. There could have been no inoculation of a particular strain as, well, living in a ger (aka yurt) one just doesn’t have access to that kind of storage. This probably explains the wariness one needs to have when first tasting the stuff as it was so inconsistent. When it was good and fresh and a little bit cool, it was not strong, but there were red cheeks and smiles all around.
There was another more mysterious beverage we called trick water. I don’t think it was distilled, but it left me chameleon eyed the next day. They tried to convince me it was made from yogurt, but I wasn’t buying it. Ah those were the days.
I’d always liked the Patagonian theory. I took comfort in knowing the europeans brought some accidents back to the old world: a grand irony to the accidents they brought to this one. But I can get used to the – roof of the world magic trickling down to the little people – idea as well.
To follow up with a little more detail on the Ayrak (fermented mare’s milk). I too was a PCV in Mongolia (’09-’11) and got to experience the wariness John B described approaching a cup, some cups were quite refreshing while others were sour and tasted quite similar to how I’d imagine licking a horse would taste. Ayrak is fermented with lactobacillus, which makes sense fermenting in a sack open to whatever was flying around in the maker’s ger or was added from previous batches. A colleague of mine, who worked with herders said the ayrak could only max out around 3% ABV given the natural level of sugars in the milk. I believe the “Trick Water” was what my Mongolian friends called Mongolian “vodka” or Mongol Arag. This is a distilled version of the ayrak kicking the stuff up to 10-15% ABV. I actually got to see a homemade still of a guy who makes it in his yard, which was pretty cool.
Isn’t Tibet’n barley as well, regarded as the oldest known cultivated? What else do we owe to the Roof of the World peeps?
The whole Yeti relationship from Tibet to Europe to Patagonia should be explored more fully – I suggest contacting the “Looking for Sasquatch” show could do a few episodes on this. Seriously, the mountainous connection seems logical and so I must say, thank you to Aga and Kubla Khan, if you knew what you were doing, or not.
Someone should add an addendum to New Lager Beer on how to track, trap and inoculate wort with a Yeti. Folks can recover from the certain Yeti mauling during the long fermentation schedule.
Im sure, in the famous footage of Bigfoot, that he or she has a mash paddle in its left paw. It all becomes clear!
so who will be the first to brew a Tibetan Lager? Tibetan Barley and yeast… What would the hop schedule look like?