Beer has been around for about 10,000 years. Pretty much the length of modern day human civilization, but in the late 1800s (1860 to 1880) A huge change accrued that most of us take for granted.
For the first 9,800 years (or whatever) humans have been fermenting Ales at room temperature. But by mid 19th century in Bavaria, they were fermenting at a cooler temperature and the beers were significantly better.
Danish Brewer Carlsberg went to Bavaria to find out why and how. He isolated the Lager yeast (cooler fermentation temperature), and in a matter of 20 years, 98% of the world’s beer was converted from Ale to Lager. That my friend is about .2% of human civilization. One brewer armed with a microscope, who was concerned about the quality of his beer, changed humanity forever.
And that my friend is a quantum leap.