> > > About 10 k years ago those humans who had begun to consume milk
> > after the domestication of cattle, sheep, etc. genetically evolved
> > a mutation in the production of the enzyme lactase by which to
> > continue the metabolism of milk after infancy.
"Although it may seem eerie & interesting at first that some humans have
a
mutant lactase persistence allele, lactose is only the sugar in milk.
Mutated humans never "evolved to continue the metabolism of" casein,
insulin-like growth factor 1, chol, estrogen, etc in milk after infancy,
especially not across species."
Humans have no problem metabolizing those proteins you mention. What is
your point? What about "across species" for plant proteins?
"It may be an example of junk DNA
http://en.wikipedia.org/wiki/Junk_DNA
since it doesn't really serve an evolutionary function for humans to
tolerate breast milk sugar after infancy."
As the wiki says, one interpretation of "junk dna" is to be a reservoir
of potentially beneficial genetic change for changing situations. There
are no "evolutionary functions" to be served. Evolution simply means
change over time. This change is seen in the greater number of those
who survive in the next generation who have that genetic change. This
change made available a new domain of nutrition not previously commonly
available at ones doorstep, so to speak.
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