>If there is this link between being PTC tasting and non-tasting and how one
>tastes those greens, would the instincto interpretation be that the
>physiology of tasters is unable to handle PTC (or whatever key part of the
>molecule produces the taste) and that they are therefore being protected
>from it by getting that horrible taste?

No ,
i am going to try to explain how i see it
the existence of an alimentary instinct is the result of the
accumulation
of experiences over many many generations . who allow a  memorised
genetic
recognition of the food.

in other  words,  for the body to be able to recognise a molecule
present in
food , it must  have encountered this food previously itself or its
ancestors,.thru genetic memory .

the instincto theory will say that the instinct works only with
potential
food in their natural state.
i don't know what is PTC but if that molecule was not part of a food
that
could have been or is eaten by us or ancestors, they will be no
instinctive
response to it ( meaning change in taste in  accordance with
physiological
states) .except to keep us away from ingesting it if it  was part of
our
natural environment
but not eaten.

In case of a new molecule never encontered before , the body have no
means
of "recognition" it is lost.

The bitterness , in greens will be pleasant or unpleasant depending of
the
body needs for the food that have this characteristic.
With A non food molecule , the taste will not change in one individus
no
matter what is it's physiological state. It doesn't stop 2 difterents
individus to have 2 different experiences with it

I used to wonder why i could not enjoy wild greens in the past now i
can
truely enjoy their strong taste.
jean-claude