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From: eddy@boulder.Colorado.EDU (Sean Eddy)
Newsgroups: sci.philosophy.tech,sci.bio
Subject: Re: Knowledge and the Academics
Message-ID: <1369@sigi.Colorado.EDU>
Date: Tue, 16-Jun-87 09:57:15 EDT
Article-I.D.: sigi.1369
Posted: Tue Jun 16 09:57:15 1987
Date-Received: Sun, 21-Jun-87 06:35:21 EDT
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In article <1142@aecom.YU.EDU> werner@aecom.YU.EDU (Craig Werner) writes:
>	I'd like to point out the difference between heritable and
>genetic (or inheritable).
>	The number of digits a person has is determined by genetic
>factors, but that number has a very low heritability.
>	Skin color in the United States is very heritable.  In Sweden
>and Japan, it has a very low heritability.
>	Heritability is not a measure of genetics.  It is a measure of
>variation.  It is roughly defined as:
>
> 	h = Genetic variation / total phenotypic variation
>
>where total variation is 
>	(genetic variation + environmental variation + error of measure)

Now hold on. Heritability sure is a measure of genetics; otherwise
it wouldn't be in every genetics textbook I've ever owned.

I'm not being facetious. Heritability is a measure that is very
helpful in agriculture (where you can ethically breed organisms
to be 'better'). The higher the heritability for a particular
trait, the easier it is for one to 'improve' that trait through
breeding programs.

Such a program not only depends on the trait being genetically
determined, but also on the capability of the trait to be varied.
This is the reason for the invention of the number called 'heritability'.
Choosing examples such as 'number of digits' are unfair,
since there is little variation.

But IQ scores are distributed on that classical (artifactual?)
Gaussian curve. That's why heritability is indeed a legitimate
measure to discuss; because if the heritability of IQ is high,
one can imagine that the IQ of the race can be improved through
careful breeding. Not a pleasant concept, but that's why the
issue is controversial.



- Sean Eddy
- MCD Biology; U. of Colorado at Boulder; Boulder CO 80309
- eddy@boulder.colorado.EDU		!{hao,nbires}!boulder!eddy	
- 
- "Don't drink and drive. You might hit a bump and spill your drink."