Ales and Lagers

Beers fall into two broad categories: Those that are produced by top-fermenting yeasts (ales) and those that are made with bottom-fermenting yeasts (lagers).

Ales came first, when brewers weren't exactly sure what role yeast played. Because ales were unstable, brewing ceased in warm weather and brewers would store reserves in as cool or cold an environment as they could find. Brewers storing their beer in very cold Alpine caves found that their beer was more stable because the yeast had sunk to the bottom.

We won't go into the evolution of this yeast, but this storage (lagerung in German) naturally selected bottom-fermenting yeasts. Operating at colder temperatures these yeasts worked slower, producing beer more attenuated, cleaner, rounder and less fruity than ales. Fermentation took one to three months.

Ales include everything with ale in the name (pale ale, amber ale, etc.), porters, stouts, Belgian specialty beers, wheat beers and many German specialty beers. They generally have a more robust taste, are more complex and are best consumed cool (50F or a bit warmer) rather than cold.

Lagers include pilseners, bocks and dopplebocks, Maerzens/Oktoberfests, Dortmunders and a few other styles found mostly in Germany. They are best consumed at a cooler temperature than lagers, although anything served at less than 38F will lose most of its flavor.