The term 'pain', to the best of my knowledge, has no scientific
definition.  As such i would think it safest to say that the question is
unanswerable because we don't know what we're supposed to measure.
Similarly, happiness, while even having a unit (the util), has no
objective definition even among humans, and questions regarding how to
make a mollusc happiest would likewise be unanswerable.

More specifically, pain as understood by humans is a human experienced
sensation that is only definable vis-a-vis human neurology.  We could
monitor the brainwaves of person who claims to be experiencing pain, and
gain a neurological signal of what pain is.  (Its probably been done.
Its probably also not the same across different humans.  But this is
certainly not my area of expertise).  However, that 'definition' is not
transmittable to organisms whose neurology isn't homologous to ours.
That molluscs have 'brains' is only true by analogy.  (In fact, the most
recent common ancestor of molluscs and humans had no organs whatsoever,
much less a brain).  So unless the neurology and psychology of molluscs is
secretly a hot research topic, no one knows the real answer.  i would
claim that molluscs do not experience 'pain' in any way that we mean the
word.  (This is not to disagree on that cephalopods are capable of a great
range of neurological activity which may include a pain-like perception,
but this is in no way similar to the sensation humans feel because their
brains are independently derived).

Now, as to awareness... Its hard to even define what this means in humans
much less anything else.  I leave this to the theologians and
metaphysicians.  It has not been defined scientifically, probably cannot
be, and is thus a matter of faith that we are in fact aware and not just
responding.  (In particular, there exists research which shows that our
brains construct reasons for why we do things after we have done them in
cases where there is not much time to think about the decision.  Our
perception that we are aware/rational may just be a neurological
illusion).

As to the point of the original question, if the person has problems
causing pain to molluscs, one might ask 'why kill them in the first
place?'

Of course, it has also been pointed out to me that boiling molluscs kills
them instantly, at which point they have little-no time to experience
anything, so pain, if they experience it, should be minimalized.

Cheers,
Nicholas Johnson

The University of Chicago
Committee on Evolutionary Biology

On Tue, 14 Mar 2006, J. Ross Mayhew wrote:

> As Paul has pointed out, it seems unlikely that most molluscs, with
> their *extremely* limited brain-power,  experience any more than the
> faintest inklings of awareness or "pain". That said, Octopi and squid
> are most assuredly capable of experiencing MUCH more, both
> quantitatively and qualitatively, than a scallop or Thais - they are
> alert, surprisingly intelligent beings capable of learning more than
> most folks realize, and solving problems the average poodle would find
> daunting.  Therefore, i think it safe to say that the topic of what, and
> how much invertebrates in general or molluscs in particular "feel" or
> are aware of, is a relative one that applies even to the "lower" levels
> in question - a filter-feeding Mytilus certainly doesn't have any
> "feelings" in the way we usually define them, while i am not sure the
> same thing could be said for something like a fish-eating Conus or other
> advanced invertebrate predator: on one end of the "invertebrate
> spectrum", the more active Cephalopods are clearly "aware" on some
> level, and more likely to experience things such as "pain", while a
> filter feeder would indeed be closer to an amoeba in these respects -
> but can we categorically say that all the organisms inbetween these two
> extremes are completely and absoloutely unaware and incapable of
> exeriencing something approaching what we as humans would term "pain?
> (and if that ramble seemed a tad garbled, please forgive - i just pulled
> an "all-nighter": something which just **doesn't** seem to get any
> easier as one grows older......).
>
> From the Great Wet North on a true Spring day,
> Ross mayhew.
>
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