Ron: Thanks for this back and forth.  Much appreciated.  So to pick back up:

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[Jim]  There is so much room within which one can operate while still being
paleo, that I still don't get the "one size fits all" concern.

[Ron] For most Europeans, perhaps.

[Jim] Interesting.  So you’re saying that there are groups of people, mostly non-European (but some Europeans as well), who have evolved to the point where they *require* grains and/or beans and/or dairy in order to be healthy?  That’s a new thought to me.  I’ve always assumed that anyone can thrive on a base paleo diet and that some populations *may* be able to add non-paleo foods to varying degrees of success.

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[Jim]  It seems to me a very strong argument can be made that concentrated
sources of sugar, whether starch or honey or fruit, were not a dietary
staple for humans over the long course of our history. 

[Ron] I would agree that is probably true for most humans. 

[Jim] Innocent question.  What populations thrive on high carbohydrate intake?

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[Jim]  Potatoes never.  Not only are they nearly 100% carbohydrate, but they
are poisonous.  Not even remotely arguably paleo, in my opinion.

[Ron] They can become poisonous from exposure to sunlight, but I don't know
which natives cultivated them and whether they did so for long enough to
adapt to eating them. Do you? 

I don’t either.  Thus caution.