They hadn't invented towels, and had to wipe their hands somewhere. :')
Here I have pictures to support my claims, and I'll you what ... those caves are surrounded by all sorts of legends of the most CREEPY kinds.
The caves were inhabited by fairy princesses and ogressess who imprisoned men and drank their blood ... better watch out SCiv ... if you think that US left-leaning feminists are bad, imagine being imprisoned in that cave by a Pyrenean nature spirit.