Re: [asa] How big a deal is homology?

I like, "If evolution didn't happen, then God went through a lot of
effort to make it look like it did. "

That's understandable (even if perhaps not accepted) by the non-technical.

JimA

Terry M. Gray wrote:

> Brent,
>
> How big of a deal is homology in paternity testing? Or DNA
> fingerprinting? Or establishing the human family tree? Or the dog
> family tree?
>
> What is the explanation for homology if it's not common descent? Why
> isn't it 100%? Why does the degree of homology seem to be less as the
> putative evolutionary divergence increases?
>
> I will grant that using homology to detect evolutionary relationships
> presupposes common ancestry (just as it does in paternity testing,
> DNA fingerprinting, pedigree analysis (and manuscript transmission)).
> But the mechanisms of transmission and change of genetic material are
> known. It's not unreasonable (unless you have some philosophical or
> theological or other reason not to accept it). However, the trees
> generated by analysis of homologies are not presupposed and the
> results are remarkably consistent with an evolutionary interpretation.
>
> If evolution didn't happen, then God went through a lot of effort to
> make it look like it did.
>
> TG
>
> On Mar 27, 2007, at 10:09 AM, Brent Foster wrote:
>
>> This is a question for those on the list who know more molecular
>> genetics than I do (almost everyone!). Now that the human genome has
>> been sequenced, as well as that of several other organisms,
>> sequences can be compared and checked for similarity. Much has been
>> made of the 95 odd percent similarity between the genomes of humans
>> and chimps. And of course the 80 odd percent similarity between mice
>> and humans. Anti-evolutiuonists point out that the similarity is
>> only 95 or so percent, not the 98% once claimed. Ha! And of course
>> mice are even less similar. But isn't the problem that there is any
>> similarity at all? Aren't family relationships demonstrated by
>> matching identical sequences of DNA that are long enough to rule out
>> coincidence? And aren't these same types of similarities found
>> linking different species, genera, families etc, such as humans,
>> chimps and mice? Maybe I'm demonstrating my ignorance of molecular
>> genetics. Does 95% similarity between human and chimp DNA mean !
>> that 95% of the sequences are similar? I ask because I am involved
>> in discussion with someone who is skeptical of DNA comparisons.
>>
>> Brent
>>
>>
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>
>
> ________________
> Terry M. Gray, Ph.D.
> Computer Support Scientist
> Chemistry Department
> Colorado State University
> Fort Collins, CO 80523
> (o) 970-491-7003 (f) 970-491-1801
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Received on Tue Mar 27 22:45:40 2007