Dear Dr. Ayala,

 

Some years ago I read an article you had written for Scientific American back in 1974 (?) entitled, "The Mechanisms of Evolution." As I read the article, two separate points jumped out at me, and I have wondered ever since if you have contemplated the significance of those two points taken together? Paraphrasing from memory,

If I am not terribly mistaken, these two points taken together call into question the resolving power of Natural Selection and its ability to promote the infiltration or removal of a mutation into or out of a population.

 

These two points seem to undercut Darwin's conception of gradual evolution by Natural Selection. The fitness of an organism must have far less to do with the presence or absence of a particular mutation than with the unique combination of hundreds or thousands of allelic genes. (Catastrophic mutations are an obvious exception). And since each individual in every generation receives its own unique mix of alleles, fitness is not heritable from the parents in the same sense that genetic traits are heritable. Rather, individual fitness must be largely random.

 

Can you correct my understanding of this matter? Or, am I possibly on the right track?

  

Sincerely,

 Jim Pamplin

 

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Dear Dr. Ayala,

 

Thank you for your response to my inquiry. Your comment that my logic is flawed, which I take very seriously coming from a scientist of world renown, professor of biology, philosophy and logic, gave me pause to wonder, just what is my logic? Boiling my own verbiage down to brass tacks, I think my logic must goes something like this:

 

IF

1. The fitness of an individual organism is based on its genotype – a unique combination of thousands of allelic genes (your first point), and
2. Each individual genotype is probably unique in the history of the universe, so great are the number of possible allelic combinations available to offspring even of the same set of parents (your second point), and
3. Unique genotypes are not transmitted to subsequent generations (by definition),

THEN,

4. Individual fitness is not transmitted to subsequent generations, i.e., fitness is not heritable in the same sense that individual traits are heritable.

The best formulation of natural selection, which has come to my attention, is given by John Endler in his 1986 book, Natural Selection in the Wild. It carefully avoids the stigma of a tautology by stating,

 

IF, within a species or population, the individuals

1. Vary in some attribute or trait q (physiological, morphological, or behavioral) – the condition of variation;
2. Leave different numbers of offspring in consistent relation to the presence or absence of trait q – the condition of selection differences;
3. Transmit the trait q faithfully between parents and offspring – the condition of heredity;

THEN,

4. The frequency of trait q will differ predictably between the population of all parents and the population of all offspring.

 

If conclusion D in my syllogism above is correct, then Endler’s condition B must be voided. Individuals do not leave different numbers of offspring in consistent relation to the presence or absence of trait q. And, barring condition B, Endler’s formulation of natural selection fails.

 

Dr. Ayala, my questions are two:

1. What, if any, logical flaw do you find in my syllogism above?
2. Are you aware of any formulation of natural selection which can survive the loss of a consistent relation between the number of offspring produced by an individual and the presence or absence of a trait q in that same individual?

Thank you again for encouraging my interest in this matter.

 

Sincerely,

 

Jim Pamplin

Dear Dr. Ayala,

 

Thank you for communicating with me again about this fascinating subject. I appreciate your kindness very much.

 

I think you may agree that Endler's condition B (individuals leave different numbers of offspring in consistent relation to the presence or absence of a trait q ) pertains only under conditions and to the extent that the rule of your first point is suspended, (short-circuiting my syllogism and its conclusion that fitness is not heritable in the same sense that genetic traits are heritable). An individual's fitness depends on its unique allelic mix (your first point) unless the influence of one allelic contest (for example trait q versus q' ) overwhelms and suppresses the combined effect of genetic differences at thousands of other loci. Only when the selectivity of a trait q is so great as to overshadow the influence of many other genetic differences, will individuals leave different numbers of offspring in consistent relation to the presence or absence of trait q.

 

This is important because it shows that very low profile allelic contests, and indeed contests between whole unique genomes, are sometimes suppressed by high profile, high selection trait competitions. In fact, as you have pointed out, there are thousands of examples of this condition in nature and in the laboratory.

 

I would venture to guess that most high selection trait competitions are between wild traits and their catastrophic or debilitating mutant variations.

 

It is my understanding that a large majority of mutations are very close to neutral in terms of selection. And yet these are the grist of the cumulative natural selection processes to which biological complexity is attributed. Of necessity, the fine tuning of genes coding for highly complex biochemical pathways and their regulatory control systems must involve innumerable small steps of low selection if such systems are to be explained naturalistically. (The accidental occurrence of high selection genetic innovations to create such complexity would challenge the probabilistic resources of the universe and invoke Miracles.)

 

So, it appears to me we are caught on the horns of a dilemma:

This goes to the heart of the resolving power of natural selection. If low selection genetic differences cannot be teased out from under the umbrella of larger contests to experience the scrutiny of natural selection, they cannot participate in cumulative selection to achieve biological complexity.

 

So, my question is-

how can natural selection achieve the resolving power necessary to create highly complex biological systems? 

 

Very Sincerely, 

Jim Pamplin

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July 14, 2006

Dear Mr. Pamplin:

I regret that I don't have the time to engage in discussion/tutorial with each of the many people who write me with questions/challenges about the theory of evolution. I usually briefly respond to the first query, but not to the ensuing ones.

I will only add that your "guess" in paragraph four is mistaken.

Sincerely yours,
Francisco Ayala

Thank you, Dr. Ayala,

 

I understand, and appreciate your having made these exceptions.

 

Best Wishes. 

Jim Pamplin