>>I have been trying to think of the best way of responding to Glenn's
musings on probability. Before I actually go to the trouble of typing
something in it may be a good idea to get some clarification on what Glenn
was proposing. I believe that either I or Terry have misunderstood. I thought
I "heard" Glenn arguing that the multitude of different functional sequences
possible revived some hope for the possibility of constructing a protein
purely by chance. If this is indeed the proposal, then the creationists
objection mentioned above is entirely appropriate.<<
O.K. Brian, here is what I see is the danger in all current calculations of
the probability of creating functional proteins by purely random chance. I
will put it in terms of sentences with equivalent functionality because it is
easier for everyone to understand. As everybody knows, I am a geophysicist,
who meddles everywhere as a gadfly, so I will admit the places I am uncertain
of. Those of you who are more qualified than me can hit me with a
two-by-four where I am wrong.
Consider the two sentences,
"If you want warts, pick your nose."
and
"When a digit is placed in a nostril the finger produces calloused bumps."
Viewed as sequences, these two sentences represent two families of solutions
to the same functionality. One may be more efficient than the other but both
say the same thing. Their length is different. By analogy, let the second
of these sentences represent human cytochrome C. Pig cytochrome or bread
mold cytochrome could be represented by minor changes to the sequence like
"When a finger is put in a nostril the finger produces calloused bumps."
or
"When a digit is inserted into a nostril the finger produces calloused
bumps."
All of these are in the same family of solutions. The question I had asked
Yockey, and to which he did not respond, is the same question I asked you to
ask him. In protein space, is it possible that other families of solutions
to a given function exist, similar to the first sentence above? If this is
possible, then there is every chance that a purely random search would find a
functional sequence. If this is impossible, then random search will fail as
you noted.
This is why I think the probability argument needs to be cleaned up. The
only way that we can get a clear answer is to calculate the volume of
sequence space which is occupied by a particular functionality. It is
functionality which is important to the mathematics of this question, not
sequence order!
Earlier tonight I noted that cytochrome C comes in sequence lengths from 103
to 112. This is somewhat similar to the sentences above. They are coming in
different lengths. So in order to calculate the volume of a particular
functionality, in sequence space, one needs to know how many families of
seqeunces can produce a given function and the distribution of sequence
lengths of those families.
To see this, assume for a moment that the sequence Leu-Ser is capable of
performing cytochrome's function and it is the shortest sequence which can do
that. In this case, if you randomly make 70-residual-long sequences, you
would be amazed to find that one in 400 sequences have that combination. (If
Gordie Simons thinks that the duplicate occurrences of leu-ser in a
70-residual seqeunce lowers this probability significantly, maybe he should
comment.) Thus it is not unlikely to find Leu-Ser contained in a 70
sequence. Cutting the 70 unit sequence with two cuts at randomly chosen
positions, gives you a 1/5000 chance of cutting the leu-ser sequence. With
the number of proteins in a lab vat, this is a high probabiliy event. As
long as the probability for finding a given functionality is in the range of
10^-14 to 10^-18, it is likely that given the volumes of proteins which could
be made, and the time frame we have, that a given function could be found
randomly. It might not find cytochrome C but it might find an equivalent
functional molecule.
The problem, mathematically as I see it, with all the probability
calculations is that we have not done a sufficient job of sampling the
functional space. We have assumed that 1 sequence = 1 function. This may
not be true. It may be that trillions of sequences = 1 function.
This is why, when I read that Gerald Joyce was finding a given functionality
in his test tubes at a rate of 1 out of a million sequences, I knew that the
probabilty argument was in trouble. And frankly, it was the probabilty
argument that convinced me that evolution was untrue. But if that argument
is weak for all the reasons I have cited, then the evolutionists scenario MAY
be correct.
This is a minor point. I disagree that the best answer to the probabilty
argument is in the non random search. At least for this ex-YEC, the best
answer is to calculate functional volume as a proportion of the total volume
and then see what the probability is. The whole point of the probability
argument is how did the reproductive machine arise. Once you have a cell,
whether God-created or naturalistically derived, the search is no longer
random. But prior to the first cell, the search must have been rather
random! It is this point which gives the probability argument its force with
anti-evolutionists.
As I have said before, I do not know if God pre-programmed into the universe
the rise of the first cell or ;whether it was miracle. But the only way I
can find out is by doing this calculation outlined above.
Does anyone know whether or not other, totally different families of protein
sequences are able to perform cytochrome C's function? (or other
functionalities?) In other words, what is the nature of functional space as
opposed to sequence space?
glenn