On Thu, 29 Jan 2004 14:35:39 +0000 (UTC), 
Kevin Aylward  wrote:
> Tim Tyler wrote:

[snip]

>> Equating "fitness" with "that which replicates the
most" is
>> confusing nonsense.
> 
> Not at all. "replicates the most" is quite clear indeed. It is simple
> English. What replicates the most is whatever replicates the most.
> Period.

The frequency of an allele can increase in a population due to random
genetic drift. In a simple case, the allele may be neutral. In other
words it's "fitness" is zero.

Think about what this means. It means that there are alleles that
replicate the most but have nothing to do with fitness. 

Similarly, there are alleles that may be beneficial (i.e. they have
a positive fitness) but they may replicate less by chance and may be
lost from the population. 

> Please feel free to define fitness, without using the concept of the
> most number of replicants.

In standard population genetics theory the fitness function (s) 
represents the probability that a given allele will be passed to the 
next generation. You can plug this value into various equations in order 
to calculate the *probability* that the given allele will become fixed
in the population or eliminated. 

There is a clear correlation between the fitness of an allele and the
likelihood that it will replicate more often than a less fit allele.
But, and this is an extremely important point, there is no guarantee
that more fit alleles will, in fact, replicate more often. Evolutionary
theory deals with probabilities not with absolute laws. There is a large 
chance component to changes in the frequency of alleles in a population.

It's appropriate to define fitness in terms of the probability that an
allele will be replicated more often. Nobody is objecting to that kind 
of definition. What we're objecting to is your assumption that any allele
that replicates the most is more fit. This is not correct. 

>> You can replicate a great deal - but if the copies all die,
>> the resulting fitness can be low.
> 
> I already explained that "replicates the most" in no way implies
> replication rate on its own. In refers to the total numbers observed,
> that's why its a tautology. However, it brings to the forefront that if
> Replicators exist, we observe the "best" ones.

What we observe are the lucky alleles, not the "best" ones. Some of the
lucky alleles may, in fact, have increased their frequency in a population
because they are more fit. On the other hand, there will be lots of lucky
alleles that are effectively neutral, and even some that are actually
detrimental. You seem to be making a fundamental error in assuming that
the high frequency of an allele in a given population necessarily correlates
with high fitness. Evolution is about probabilities. The actual genetic
composition of a given population is a combination of all kinds of events
in the history of the population. 

>> Substitute "fitness" into your preferred motto and you
get something
>> more like "survival of the fittest" - which fewer will object to.
> 
> You problem is that you are conditioned to read into something that
> simply isn't there. You are the first, I believe, to have objected to
> that statement, so the misunderstanding would appear to be yours.

The misunderstanding is yours. Your motto is ...

 "That which is mostly observed, is that which replicates the most"

There's nothing seriously wrong this this statement as long as you
recognize that there can be many reasons why a given replicator has
replicated more often than another. However, on your website you 
insert the following sentence immediately after your motto.

 "This statement, is in essence, a tautology. Indeed, it is more 
  often known as 'survival of the fittest'."

This is where you go wrong. There's a big difference between those
alleles that replicates the most and natural selection. You are making 
the false assumption that the only explanation for the most replication 
is because the allele is more fit. In other words, you don't seem to 
know anything about random genetic drift or population genetics.

This error is commonly known as the adaptionist fallacy. It refers
to the false assumption that the only mechanism of evolution is
natural selection. People who make this false assumption will often
refer to evolution only in terms of "Darwinism" and selection. You 
do this on your website when you define evolution .... 

  "Definition - Evolution is any process that satisfies the 
   Darwinian axioms of random generation, selection and replication."

That's one reason why your entire "theory" is irrelevant and wrong.




Larry Moran
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