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

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