Brain Mass Concepts

Filip van den Bergh F.S.vandenBergh at
Thu Sep 13 09:39:05 EST 2001

I of course begin with a statement of humility: Other are probably better
able to answer this question, but I will give you my answer because few
others have.

The theory you are discussing has to do with between-species variability. It
is not assumed (at least not anymore) that brain mass of an individual is a
predictor for the relative intelligence of that individual compared to other
individuals of the same species. I don't think you thought this was the
case, but one of the replies suggested that the question was interpreted as
Now my h opinion on the evolutionairy component of your question. I don't
know where you got theory regarding your question, but I'm certain that in
that same book, there is a picture of a sensory or motor homunculous. The
sensory homunculous shows the relative sensitivity of the various bodyparts.
Large bodyparts have larger sensory areas, because many sensory neurons are
needed to tell the brain what's going on with that bodypart. Of course, some
area's of the skin are much more sensitive, such as the indexfinger. So that
part of the body takes op more space on the sensory map. Now imagine a
whale. It would need huge sensory areas to know what's going on on the huge
whale body. As for motor areas of the brain, that was answered by someone
else up the thread.

(although a student of neuroscience, not at all in this field)

Miles Robinson <m-robinson7 at> wrote in message
news:9noo7q$dm8$1 at
>     I have a basic question about brain mass studies. It has been supposed
> that the brain mass to body mass ratio can give realtively good
> measure of "intelligence". However, when looking at the brain as a control
> system for the body, it's hard to overlook that fact that a larger body
> does not necissarily require a larger brain to maintain equivalent
> functionality. For example, a single muscle doesn't require more neurons
> it gets larger during the evolutionary process as far as I can see. I
> this way because an entire muscle moves together and thus the whole organ
> gets the same signal from the brain, so why is it necessary for multiple
> neurons to control something that only requires as single signal? Is it
> more reasonable to use the critera of number of organ systems or
> vs. brain mass to quantitatively evaluate intelligence? Or better yet the
> number of body systems to brain divisions?
> Thanks
> Your attention appreciated
> EE student at Northwestern U.
> (Not a neuroscience student)

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