Kinda wild. My lady asks me a bunch of questions about beer and also homebrewing. She asks, why after primary, why don't you stir up the trub and see if the yeast becomes active again. I say well maybe because introducing oxygen in that phase causes oxidation and the yeast has done its work. BUT, I want to entertain her curiosity and stir it up after a week or at least after it stops its main activity. We made a test subject with DME and no hops. We used a packet of s-5 yeast. I stirred it up this weekend. I have activity still. I'ts only 2 quarts of beer. Its an experiment. Also today she asked, why are hops added. I told her to offset the balance of the sweet wort and to balance it out. but I told her there are other things you could add to beer to offset the maltiness. I just thought it was cool that someone was interested enough in my hobby to ask such questions. What good responses could I tell her?
Some people will try to rouse the yeast if they think fermentation has stalled. Get them back into the mix to see if they shave a few gravity points off the beer. As you surmised, introducing oxygen at this point can be a pitfall, so do it gently. Hops were also allegedly added for their preservative power. Souring bugs such as lactobacillus are inhibited by compounds in hops. But you are right, traditionally, other bittering ingredients were added to ales, too.
Stirring up the yeast, even if attenuation was already finished, will give the appearance that attenuation has been restarted, because CO2 will be released from solution. Unless the fermentation is stuck, this isn't a good idea, because of the risk of oxidation, as already mentioned. I believe this topic and the "why hops" question are both covered a little bit in ... www.howtobrew.com ...which I would recommend (for your lady).
as for other things added to balance beer: If you haven't already, buy a copy of "Radical Brewing." It describes flavor additives used in beer, and the flavors they impart, throughout history. Juniper, mugwort, wild rosemary, heather... etc..., etc...,etc...
I'll have to pick up this book. After all, I've already been using Juniper (twice) and elderberries (twice) and both beers came out tasty! Twice!
