Did you hear that?
The click of the heaters turning on?
The crackle of wood stoves and fireplaces?
How about the sound of a top crack?
The sound of a lower bout popping from its rib?
Wood is alive, and it's always moving. A little movement is to be expected...but a lot of movement? Not so good. So how do you stop your bass from moving? Humidify. Its easy. Really easy. Anyone can do it. And if you own a bass (ok, any wooden musical instrument!) then you should, nah...you NEED to be.
Luthiers don't go to heroic efforts finding good wood from wood cutters who know how to cut and treat timber, store it properly, take every precaution know to them, spend months making, and try to educate their cliental about caring for their creations...just to have that same client call up in the middle of February and say "I don't know what happened."
Humidify. It's easy...and pennies on the dollar compared to repairs and devaluation from abuse.
OK...Rant over! ;)