Todd > Given that limitation, I don't see any honest way to deny that
rennet-fermented cheese could have been eaten regularly.

Oh, I see it very, very differently.  And I consider myself to be possesed
of a modicum of intellectual honesty.

Both from a volume standpoint and from a time standpoint, the amount
required for a food to become a natural part of our diet is far from
conclusive, it is true.  And I am willing to admit that there might exist
some diversity among peoples as to what they can and cannot tolerate.  But
it seems to me that two things stand firmly against the inclusion of cheese
in the list of foods our ancestors ate often and for long enough that we
were able to adapt to it.  First, an argument from experience.  Many, many
people find themselves unable to eat the stuff without obvious problems.
And maybe those that can aren't showing the ill effects in quite so obvious
a fashion.  Second, it seems to me something of an ad hoc hypothesis to
assume that the stomach contents of these suckling animals would be
considered edible.  I mean, that's what we're arguing about, right?  If
they were us (and they were since, as the Eades say, we have changed
genetically 5 one-thousandth of a percent in 10,000 years), an argument
that's just as fair on the other side could be made that they were smart
enough to know to avoid eating the stuff since it's bad for you.

There's plenty of room for denial that cheese was eaten regularly in the
many hundreds of thousands of years of our existence.  To my eyes, the
evidence we have suggest avoiding dairy altogether if you want to remain
"pure" from a paleo standpoint.  But common sense says to enjoy an
occasional slice of peccorino with my chianti classico.  It's probably not
as bad as a ham sandwich or pumpkin bread.  But I'm not going to fool
myself into thinking that there's not a price to pay for this decision from
a health standpoint.