why did poppies evolve opium?

Burt Voorhees burt at aupair.cs.athabascau.ca
Wed Sep 23 11:44:25 EST 1992


wadley at mullauna.cs.mu.OZ.AU (Gregory Robert Wadley) writes:

>I'm having real trouble finding this in the literature,
>so any tips or pointers would be appreciated:

>(1) Opium would appear to be something that _encourages_ animals to eat
>    poppies.  So what is the advantage of containing opium?

  The animal eats the poppy, the poppy seeds pass through the animals gut
and emerge at the other end with free fertilizer.

>(2) Or does opium have some other purpose, and only incidentally is narcotic?

>(3) Is it reasonable to say that plants like the poppy, tobacco etc, are
>    "taking advantage" of human's desire for the substances they contain,
>    in the sense that there are more of them, because we cultivate them?

  I don't think so.  First off, I don't think we can attribute the conscious
intent which a term like "taking advantage" implies; and secondly, if there
is any advantage being made it is by us who have decided that we can make use
of these plants.

>(4) I read somewhere that opium is a _defence_ against predation, as it mucks
>    around with the predator's nervous system. Is this so?

  Don't know about this specific case, but there is a large literature on the
topic of chemical defense in plants.  Tannins are often the agents used by
the plants, and they evolve in a complex cycle of interactions with the bugs
abil,ity to digest various chemical substances.  E.g., a bug generation evolves
so that it can digest a particular plant, and the next generations of the plant
has changed its chemistry slightly so that the bugs can't digest it again.

>(
5) Is it only humans that are attracted to opium use? Alternatively, does the
>    narcotic effect not occur when the pods are eaten raw by an animal?
>    (ie do the pods have to be processed or cooked in some way?)

>(6) Do other plants contain opium? How common are psychoactive substances
>    in plants?

  See comments of chemical defense above.  Some of the psychoactive properties
might be side effects of the way the substance messes about with the digestive
system.
bv



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