Why is it that digestifs are mostly anise-flavored?

“Aniseeds have a distinctive licorice-like flavor and have been used for medicinal purposes throughout history, especially as a digestive aid.”

http://www.aniseeds.com/

Beneficial Uses:
Anise Seed has long been used as a popular remedy to relieve digestive disorders. It is a tonic for the stomach that helps relieve nausea, abdominal pain, gas pains and spasmodic flatulence. Anise helps prevent the fermentation and production of gas in the stomach and bowel and aids in expelling it. Aromatic Anise helps promote good digestion, improve appetite and alleviate cramps and “griping” (sharp pains and grumbling in the bowels). Herbalists recommend Anise to soothe colicky infants.

http://www.herbalextractsplus.com/anise-seed.cfm

anise is a known appetite stimulant.

I’m assuming it has to do with how easy it is to grow/transport anised compared with other digestive aids like ginger. Ginger is harder to find and cultivate- thus it having less people use it, traditionally, as something much more readily available like anised.

I wonder if it also has something to do with the longevity of the seed vs the faster rotting tuber?

Trillian’s clip above mentions something that leads me to speculate another reason for using anise: it inhibits fermentation. Since there’s sugar in the drink and wild yeast in the air, it stands to reason that (in days of yore) they would have used some agent to stop a secondary fermentation in the bottle after it’s opened. Today there are many fining and filtering processes by which alcohol is made stable (microbially, protein-wise etc.) but in the past you would have taken different steps.
Let’s pretend it’s a century and a half ago. You wouldn’t need to make anise flavoured wine because you’re going to open one and drink the whole thing. But that bottle of digestif is going to sit on that shelf for a long time. And you wouldn’t want any wild yeast to start another fermentation process. (Interestingly, the Austrians bottle a digestif in little single size bottles: Underburg. It’s not specifically anise flavoured, adding strength to my argument.)
I’m going to do some more research. This is the most Fluther has made me think in a while. Thanks to Andrew for sending me the question. (and have you seen the new question sent to you feature? Cool!)

They’re not. Brandy, whiskey, tequilla and fortified wines are all commonly served as a digestif.

Ah. Well lightlyseared just blew my theory out of the water. I had forgotten that they are fortified, meaning the alcohol content is raised to a level where microbial activity would not be possible. Too much alcohol for yeasts to live.

Hmm. Guess I’m going to have to go with tradition.

And not to nit pick, but tequila and whiskey are not fortified wines.