Dear Allen,
If all we had was the degree of relatedness, your argument would be
compelling. But there are a number of other important details apparent when
one compares the DNA sequences of organisms (say humans with mice, cows, or
chimps). Here are just a few:
1) The genetic code is degenerate -- there are 20 amino acids to code for,
and 64 possible codons of three bases (each of which can be A, C, G, or T).
Two of those codons code for stop. But that leaves 62 codons to code for 20
amino acids. The result is that most amino acids have more than one
possible codon. It is often the third base of the codon that is irrelevant
to the coding potential. But when you look at homologous genes between
related organisms, they tend to use the same letter in that unconstrained,
functionally irrelevant position of a particular codon of a particular gene.
Why should that be unless there is a common ancestor?
2) Gene arrangement (synteny). Genes that are within 5 - 10 million base
pairs of each other in man usually have that same order in mice and even in
fish. Yet we have few if any examples where the function of a gene is
affected by elements that are more than a million base pairs away. Why
would the linear order be so similar between vastly different organisms if
there wasn't a common ancestor?
3) Pseudogenes. There are thousands of genes in the human genome that
harbor major inactivating mutations that make them no longer functional.
They thus serve no functional purpose. For nearly all of these, one finds
the same pseudogene, in exactly the same location, in other primates. If
you go further afield, you may find that the gene in this location remained
functional in some other lineage. Why would the separate creation of all
these species include the pseudogenes?
4) Transposons. There has been a vigorous dialog on this topic on the
Listserv over the past two weeks, and the arguments are very convincing --
transposons which have no potential function, and are found in exactly the
same position in multiple species, provide a very strong argument in favor
of common ancestry.
Perhaps you will say that all of these examples simply indicate that
we have underestimated the functional importance of these genome features
(as I admit has occurred for the Alu repeat, see previous message). But to
argue that for all the features described above strains believability beyond
the breaking point. Is it not vastly more likely that God chose to create
using the mechanism of evolution? Being unbounded in space and time, He
knew quite well that this would result in humankind, and He had no reason to
be particularly concerned about the time involved in getting there.
For a more detailed exegesis of some of these arguments, see Kenneth
Miller's wonderful book "Finding Darwin's God".
Regards,
Francis
-----Original Message-----
From: Allen Roy [mailto:allenroy@peoplepc.com]
Sent: Thursday, April 04, 2002 10:02 PM
To: Collins, Francis (NHGRI)
Subject: Qs for Dr. Collins
Dr. Collins, why should the relatedness of living things point more to
evolution than to a common Designer with distinct creational categories?
Musical notes, for example, do not evolve one from another. They have
relatedness, but they come from a Composer.
An author may write many books, and there may be relatedness between them,
but one book did not evolve from the other. The connection was in the mind
of the author, etc.
Why could this not be true for living organisms? Horses may have many
similarities with catfish.
Could not the Designer make both using similar ideas without having one
evolve from the other?
Is the total number of genes in humans still around 30,000?
Allen Roy
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