Todd Moody wrote:
>Good point.  We can't answer this without answering the question
>"How old is old enough?"  I don't expect there will a simple
>answer to this question anytime soon.

Neither do I.  However, for what it's worth, a friend of mine contacted
several nutritional anthropologists (only a handful exist in the U.S.), and
the consensus was:  A minimum of 5000 years is generally needed for (not
necessarily complete) adaptation to a change in diet.

Cheers,
-- Aaron Wieland