Chris , I so agree with what you say:

It's my impression that measuring milk output has got us into lots of trouble
in the past century.  It has allowed people to see human milk and man-made
substitutes as equivalent.  "You can measure formula; you can measure human
milk; so they must be pretty much the same stuff."

I just want to say again that I think one century is not the time frame of this
confusion.  If you cast your eye back, you will see that since humans
domesticated animals there has been a pressure to use milk products in a variety
of way.  Not all peoples who have domestic animals use the milk, but it is
common.

An interesting view of the possible meanings of the use of animal milk is in
Kastrup in Maher, ed.  "the Anthropology of Breastfeeding".

I think the trend to see the two substances as similar and interchangable began
with the domestication of animals.

I keep saying this because I think it helps us to face squarely the dimensions
of the task we have on our hands, which is combatting a view which has been
around for millenia, not just a hundred years or so.

Magda Sachs
The Breastfeeding Network
Saddleworth, Greater Manchester, UK