David Ross wrote:
> with respect to the differences between human and cow milk and hence to the non-suitability of the latter for humans:
>
> "The proteins synthesized by different animal species are lined up on
> specific models that are as different on a molecular scale as physical
> traits are on an ordinary scale."
>
> This seems all well and good but aren't the proteins that constitute human
> tissue and bovine tissue just as different (as the milk) on the molecular
> scale?

They are more or less about as different. The theoretical justification
for accepting the meat in the diet and not the milk (apart from the
pragmatic approach which shows that good quality meat is OK while
eliminating milk products gives good results and that reintroducing them
brings a variety of problems in) is not how different it is from human
milk or human proteins. The relevant explanation seems to be that milk
products were not available in nature throughout evolution until very
recently. Therefore we have no reason to be adapted to a product that
wasn't available for our species in nature. We could find a dead
buffalo. We could kill a live buffalo and eat its meat (if courageous
enough or group-hunting). But we could not drink buffalo's milk because
a live adult wild female buffalo will not let a primate approach her and
drink her milk. As our ancestors have logically never drinked buffalo's
milk in the past, there is no reason for us to have the necessary
enzymes and metabolism to digest buffalo's milk. Same for cow's milk or
another species' milk. There is also no reason for instinct to work
correctly and give the stop on milk at the correct point for the same
reason.

I remember visiting Eric Billon in the early 90's, an instinctive MD who
was then living in Quebec (he now moved back to Martinique with his
family). He had gone dear-hunting in a totally virgin inhabited island
in the estuary of the St Laurent River estuary with a few instinctive
friends), a famous canadian hunting spot. When they came home from their
hunting-trip, they brought back a female-dear that they had shot on that
afternoon. Just after shooting her, they had noticed a baby-dear
standing close by, very young, still breast-fed. When they told me the
story, I felt sorry for the baby-dear, who will probably not have
survived without his feeding-mother (he was scared and ran away when his
mother was shot). But I decided to take profit of the situation for a
unique scientific test. Would it be possible to drink the milk from
mother-dear after its death ? That was the the milk from the breast of a
freshly killed lactating mammal. It was just a few hours after
mother-dear had been shot and the temperature was moderately cold on
that day (5-10°C), therefore the body was in a very good state of
conservation.
I first noticed that the milk glands were slightly swollen, which is
normal and an indication that mother-dear was indeed breast-feeding her
infant. Then I put my mouth on dead-mother-dear's breast and sucked hard
for the milk to see how it would taste and how my body would react. To
my surprise, absolutely no milk was available however powerful the
succion force. Not even one drop of milk available ! I then tried
another more radical way and dissected several of those small breasts
one after another with a knife (note that the use of a knife in itself
is already artificial). By ripping apart the tissues and pressing them
real hard, I could hardly obtain more than a few drops of whitish-redish
juice from the whole animal, not more than you would obtain by pressing
a solid fresh steack. Those few drops didn't even taste like milk at all
(more like pressed meat or blood).
The conclusion of this experiment clearly was that before our human
ancestors started raising cattle at the early neolithic period (more or
less 8-10 000 years ago), they probably NEVER had access to another
species' milk. The live animal won't let you suck it. The dead animal
doesn't have any milk available. The milk of mammals is secreted "au fur
et à mesure" only when the baby mammal sucks the breast. No milk
stocks-ed in advance. Cows with 50 liters of milk balancing under their
belly, as we can see in every farm nowadays has be obtained only
recently through artificial food given to the animals and selection of
the cows giving the greatest amount of milk.

MILK OF ANOTHER SPECIES IS NOT AVAILABLE IN NATURE. THAT'S WHY YOU
SHOULDN'T DRINK IT (or its derivatives)

On the contrary, it is possible to find a dead animal in nature once in
a while, and our instinct will therefore have had time to adapt and
develop  an instinctive stop and appeal to tell us if we need or not to
eat the meat.

MEAT CAN BE AVAILABLE IN NATURE. THAT'S WHY IT WON'T HARM US IF WE NEED
IT. and that's why our instinct will tell us if we need to eat meat or
not (mainly by the taste and smell).

Hope that answers your question ?