Many discrete kinds of beers now exist, including ales, lagers, pilsners, and ciders, to name the most popular few. But at the heart of the matter is a key ingredient, yeast, which has a fascinating evolutionary story that begins in a cave more than 500 years ago.

Lager beer is loved by people across the globe. Now, though, researchers have attempted to solve the mystery. He dubbed it Saccharomyces eubayanus. [Raise Your Glass: 10 Intoxicating Beer Facts].

But the second great beer innovation was the origins of lager beer during the 15th century, when Bavarians first noticed that beer stored in the caves during the winter continued to ferment, researchers said. Wort is the mix of grains that contain the sugars which yeast ferment into alcohol.

The findings, published in the journal Molecular Biology and Evolution, could provide a road map for future research in the domestication of lager yeasts. There were two independent origin events for S. cerevisiae and S. eubanyus hybrids that brew lager beers. Lagers enjoy a whopping 94% share in the world beer market today. The correlation between the two species of yeast – S. cervisiae and S. eubayanus – as different as humans and birds, happened twice, at the least.

The results suggest the Saaz and Frohberg lineages – named after their area of origin in Bavaria – were created by at least two distinct hybridisation events between almost identical strains of S. eubayanus, with relatively more diverse ale strains of S. cerevisiae. Hittinger reveals that the S. cerevisiae was adapted for Mediterranean temperatures and this is the reason why bread, wine and ale beers are present for a thousand years. The researchers have made its comparison to domesticated hybrids that have been used for brewing lager and that has allowed the ability of studying the entire genomes of both the parental yeast species that have contributed to lager beer for the first time ever.

That doesn’t mean all modern lager beer yeasts are the same, he adds. (“We knew it had to be out there somewhere”, Hittinger said at the time.).

Each lineage is a hybrid of two yeasts that have not mated with each other, likely because each is sterile and only reproduces asexually. However, it wasn’t till now that anyone found out about the strain of yeast used to produce it. For instance, yeast cells can sexually reproduce when they are starved of nitrogen and carbon. “You are making a bottleneck”, says Hittinger, “reducing the number of individuals, and with the yeasts, the potential is even worse”. The two types of yeast are called S. eubayanus and S. cerevisiae. The DNA study also showed why Saaz became so unpleasant that made brew makers drop it from the brewing process.

A team at the University of Wisconsin-Madison took advantage of a newly described wild yeast species from Patagonia – Saccharomyces eubayanus – to complete the genome of S. eubayanus using the latest sequencing techniques.

Elizabeth Goldbaum is on Twitter. “They could be useful for certain types of products”, such as as biofuels, Hittinger said.