Michael Ragland wrote:
 > Anon.  wrote or quoted: Tim
 > Tyler wrote:
 >
 > TT: As he says, his interpretation is an "absurdity". But Gould is
 > attacking a straw man of his own making. Noboby using the "gene for
 > X" terminology was ever asserting that single genes determined
 > behaviour - and Gould should have been aware of that.
 >
 > BO: But is the general public aware of that? I suspect not - which is
 > why things like the "gay gene" get so much prss attention. Given that
 > most people will interpret statements about a "gene for X" in a
 > literal way, I think Gould was quite right to attack the absurdity -
 > it's a straw man for geneticists, but not for the press and public.
 >
 > TT: I don't see anything wrong with a completely literal
 > interpretation: A "gene for trait X" doesn't mean that no other
 > factors are involved - any more than a "vote for candidate X" means
 > tht there are no other factors influencing the election result. The
 > word "for" simply doesn't mean the same as "determines".
 >
 > MR: I think making an analogy between a "gene for trait X" and
 > "politics" is poor and sloppy form. To use a similar analogy would be
 > to state a "gene for trait X" doesn't mean that no other factors are
 > involved - anymore than "preparing and baking homemade lasagna" means
 > that there are no other ingrediants influencing its composition. I
 > see plenty wrong with a completely literal interpretation of a "gene
 > for trait X". First of all with few exceptions there are no single
 > "genes" for particular traits. So why you cling on to the idea of
 > "gene X for a trait" as a completely valid literal interpretation is
 > perplexing to me.
 >
I think you're missing a pragmatic point: that we have to describe and
discuss science.  You do find genes that have large effects, i.e. if you
compare individuals which are genetically identical except for the
presence of the gene, then there are clearly observable differences.
And these are repeatable in different genetic backgrounds (GFP - green
fluorescent protein - springs to mind).  It is impractical not to talk
about these as genes "for" a particular trait.

I think this is OK as long as the gene creates the described effect
stably (i.e. without too much environmenal or background genetic 
modification of phenotype), and if the primary function of the gene is 
to create the described phenotype.  For example, Mla is a barley gene 
for resistance to mildew, because it is involved in triggering a 
specific reaction that leads to a resistance response.

The problem with talking about a gene for a trait is when it is not the 
primary function of the gene, but a side effect.  For example, the mlo 
gene also confers resistance, but this appears to be a side effect, 
because its primary role seems to be in inhibition of a resistance 
reaction (i.e. it stops the barley from getting too jumpy and reacting 
to anything).  I would therefore not describe it as a gene for 
resistance, even though it's jolly effective at it.

Bob

-- 
Bob O'Hara

Dept. of Mathematics and Statistics
P.O. Box 68 (Gustaf H„llstr”min katu 2b)
FIN-00014 University of Helsinki
Finland

Telephone: +358-9-191 51479
Mobile: +358 50 599 0540
Fax:  +358-9-191 51400
WWW:  http://www.RNI.Helsinki.FI/~boh/
Journal of Negative Results - EEB: http://www.jnr-eeb.org
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