Dear tsuwm: You might have noted that the heraldry term "gules" is from same root:
gules (pronounced gyoolz)
n.
ME goules < OFr, gules, red-dyed ermine, orig. pl. of goule, the mouth < L gula, throat: see GULLET6 Heraldry the color red: indicated in engravings by parallel vertical lines

I wonder if the redness of the mouth that the two words have in common