Model Organisms

L.A. Moran lamoran at gpu.utcc.utoronto.ca
Sun Apr 27 07:42:56 EST 1997


In article <3361065D.3F8F at is.dal.ca>, Arlin Stoltzfus  <arlin at is.dal.ca> wrote:
>L.A. Moran wrote:
>
>> >Among trained experts, the
>> >word "primitive" means "retaining an ancestral state".  The
>> >contrary of "primitive" is "derived".  It is a straightforward
>> >matter to apply these terms to individual characters in cases
>> >where ancestral states can be inferred.
>
>> I appreciate the point that you are trying to make but perhaps it would be
>> best to remember the context. Someone wanted to knw if there were any
>> organisms that were more primitive than Drosphila but less primitive than
>> C. elegans. Why? Because he was hoping to isolate a C. elegans gene using
>> a human probe and was looking for an "intermediate" model organism. Do you
>> think that this is a reasonable experiment? Is it consistant with your
>> understanding of evolution. (I sure hope not or I have seriously misjudged
>> you!)  (-:
>
>Yes, I didn't mean to deny the possibility that the question was 
>a bit absurd (I thought that this was implicit at the beginning 
>of my statement).  More generally, we could probably all dispense 
>immediately, today, with using the words "primitive" and "derived" 
>(or its confusing semi-synonym, "advanced") *in reference to 
>species or higher taxa* and biology would be none the 
>worse for it.  If I were the editor of an evolution journal, I 
>would explicitly forbid this usage in the instructions to authors, 
>because there is such an extraordinary tendency toward abuse 
>(a bit like the words "novel" and "striking" in molecular biology
>journals).  Of course we would want to retain these useful 
>terms for referring to individual character states.  

I agree that an outright ban would be very useful at this time. We need
to do something to alert everyone to the conceptual errors that such terms
perpetuate.

>I only wanted to warn that the history of evolutionary 
>biology (maybe other sciences too) is peppered with instances 
>in which the rejection of a false doctrine led to over-generalizations 
>that became false doctrines themselves and inhibited research 
>in interesting directions.  An example would be the over-heated 
>rejection of Lamarckism, orthogenesis and mutationism, which 
>leads to blanket statements about mutation being "random" (in 
>spite of the obvious evidence that mutation is non-random in 
>many ways, including its relationship to fitness-- there 
>is usually a bias in favor of fitness-decreasing mutations 
>over fitness-increasing ones, as everyone knows) and "spontaneous" 
>(in spite of other observations to the contrary).  

Point taken. But it's hard to see how a rejection of the ladder of life
idea could get out of hand. If everyone stopped using the words "primitive"
and "advanced" (or "lower" and "higher") to describe living species then
this could only be for the better, no? Can you think of a possible objection
to such a ban?

BTW, Anthony Pelletier and I will be discussing the randomness of mutations
in sci.bio.evoluion. Please join us. One of our problems in that newsgroup
is with definitions. We need to agree on the meanings of terms such as
"random", "mutation" and "spontaneous". 


Larry Moran





More information about the Mol-evol mailing list