The general consensus amongst beer historians is that stout beers are a derivation of porters. The story goes something like this – The use of the word “stout” back in the 1700′s (when porter was introduced) was that of an adjective, not as a noun. A stout beer was any strong beer, not just dark ales with dark-roasted barley. It was possible to have stout pale ale, stout porter, or stout brown ale, or at least the theory goes.
When Stout porters took on a life of their own, it was only then that the two types of ale began to be seem as different entities. This occurred roughly around 1820 when stout was developed as its own commercial beer style. From these two styles, further sub styles developed, such as Oatmeal Stout or Baltic Porter. But the evolution of these styles is best left for a different post.
Back to the initial question: Which came first Stouts or Porters? The answer is as follows. If your asking which came first from these styles of beer, as we know them today, then the answer would have to be porters. However, stout ales have been around as beer nomenclature for longer than porters have been around. Got that?
And what, pray tell, is the difference between a porter and a stout by today’s standards? The BJCP says that the vital statistics of a brown porter is as follows:
OG: 1.040 – 1.052
FG: 1.008 – 1.014
IBUs: 18 – 35
SRM: 20 – 30
ABV: 4 – 5.4%
Ingredients: English ingredients are most common. May contain several malts, including chocolate and/or other dark roasted malts and caramel-type malts. Historical versions would use a significant amount of brown malt. Usually does not contain large amounts of black patent malt or roasted barley. English hops are most common, but are usually subdued. London or Dublin-type water (moderate carbonate hardness) is traditional. English or Irish ale yeast, or occasionally lager yeast, is used. May contain a moderate amount of adjuncts (sugars, maize, molasses, treacle, etc.).
OG: 1.036 – 1.050
FG: 1.007 – 1.011
IBUs: 30 – 45
SRM: 25 – 40
ABV: 4 – 5%
Ingredients: The dryness comes from the use of roasted unmalted barley in addition to pale malt, moderate to high hop bitterness, and good attenuation. Flaked unmalted barley may also be used to add creaminess. A small percentage (perhaps 3%) of soured beer is sometimes added for complexity (generally by Guinness only). Water typically has moderate carbonate hardness, although high levels will not give the classic dry finish.
So the differences are basically two-fold: Firstly, stouts use roasted unmalted barley while a porter will use little, if any. So stouts will have a deeper, darker, near coffee-like flavor. Porters, less so.
Secondly: Stouts will use a bit more hops in their brewer, making for a tad more bitter beer, albeit one that’s a bit more complex.
One can be forgiven for mixing the two varieties, as there is both common history and common ingredients. But for me, the way I remember distinguishing the two is that a stout is essentially a porter times two. An oversimplification, to be sure, but it does sum it up nicely.