Are there any theories or speculations as to what causes geographic tongue?

No good theories: …although i speculate that geographic tongue may be associated with a keen intelligence.

Geographic Tongue: Geographic tongue occurs when parts of the tongue are missing layers of small bumps called papillae. They normally cover the entire upper layer of your tongue. Why do you lose these papillae with geographic tongue? Nobody knows for sure. However, because geographic tongue tends to run in families, genetics may be a common link.