Ages 8 to 88

Apparently, the recommended age ranges on board games reflect more than just the designer's idea of how complicated the game is.  In order to qualify for an age rating of less than about 10 years, a publisher has to pay to have the game officially tested for safety, which is not a cheap process-- not only would it be tested for size of components (choking hazards), but I imagine there are chemical tests for toxicity and heavy metals and the like.  So some smaller publishers will just shrug and label the game "for ages 12 and up", even if the game is actually pretty simple and could easily be played by the average 10-year-old.

Source: a thread on boardgamegeek.com.  This does seem to be the conventional wisdom (I saw references to it in a couple of places), but I couldn't track down an authoritative statement, so take with the usual sodium chloride.