I don't think there's an urban myth going on here, but rather the fact
that "primitive" cultures often recognise that the head contains the
soul, mana, magic, whatever of a person, and history records various
repercussions from this. The Scythians made drinking cups out of
great enemy leaders (see Herodotus), in a sense "drinking" the
opponent's wisdom and skill. The Celts preserved heads of ancestors
and enemies in precious oils (see Mabinogion--story of Bran, for
example), and displayed them on poles and in niches of doorways.
One tribe (I can't remember where, Africa or New Guinea, I think)
eats the brains of their dead so that the wisdom is passed down.
Unfortunately, they also suffer from a disease they contract this
way. Playing a game with the opponent's head asserts your control
over him utterly--much like the conquering peoples would steal the
idols of their rivals, thus depriving their enemies of the support
of the Gods, and possibly obtaining their power for their own side.
Elisabeth Eilir Rowan
[log in to unmask]