evo, devo, and neuro (Re: Neurotransmitters)

steve madison s.madison at sympatico.ca
Sun Feb 28 23:20:32 EST 1999



Hemidactylus at my-dejanews.com wrote:

> In article <7ake8t$ok7$1 at fremont.ohsu.edu>,
>   Matt Jones <jonesmat at ohsu.edu> wrote:
> >
> (snip good stuff)
> >
> > As for the "evolutionary garbage" idea, I think what your prof may have
> > meant is that there's always an ongoing process of mutation and selection
> > among both neurotransmitters and receptors.
> >
>
> One species' garbage might become another's treasure. This is an underlying
> theme of evolution. Gould (1991) discusses some of the issues overlooked by
> strict Darwinist evolutionary biologists. Co-option could come into play,
> where a component (morphological or molecular) previously adapted to another
> function could be utilized in a novel manner (an exaptation in Gould's
> words). One might want to consider the history of a component, in addition to
> its present function. Some evolutionary biologists or evolutionary
> psychologists might "reverse engineer" a component all the way back to the
> start from a superficial look at its present utility. Daniel Dennett and
> Richard Dawkins have been critical of Gould though.
>

Scott, since you are mentioning Gould, he mentioned a concept in his book Full
House about complexity that may apply here.  Namely that if organisms are very
simple (and there are lots, as in species, of them) more complex - multicellular-
organisms are the only way for expansion due to random fluctuations.  all the
simple plans are taken but given enough random tries (evolutionary mutations or
whatever) a more complex plan will be developed.  so if we have only the one
receptor - one neurotransmitter perfect fit, over time the situation would
naturally tend towards a more complex (multiple receptors and transmitters with
lots of cross-talk) model.i'm sure you can follow the idea despite my (i'm sure)
inappropriate use of the technical words.  it's difficult to paraphrase someone
else's field. :o)

> <snip-snip>
> > Evolution is always trying
> > out new structures by accident, and some of these turn out to be useful.
> >
> <more snips>
> > But maybe it was just evolutionarily cheaper to leave all these extra
> > proteins lying around than it would be to get rid of them once they're
> > there.
> >
>
> An argument based on efficiency might ask why this redundancy isn't plucked
> out due to costs, but this probably would assume that selection molds every
> square inch of an organism's phenotype.
>

good point.  see above.

> I raise these issues as a barometer of what people in the neuroscience
> community are doing related to evolutionary studies of neurobiology. I have
> interests in evolutionary developmental biology and would like to see how
> this might overlap with neurobiology. I've got a LONG way to go :-)

i share these interests as well.  in this molecular age we can lose track of the
forest pretty easily.

steve madison
searching for a ph.d. post
formerly of neuromuscular research lab
laurentian university




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