Geological calibration of molecular clocks

John Grehan jgrehan at SCIENCEBUFF.ORG
Mon Jul 11 12:10:51 CDT 2005

How can it be a test of the hypothesis (of the geological age of the
islands?) if it cannot give you a decision one way or the other as in
this case? It also seems a bit problematic to test one hypothesis with
another hypothesis. I am not aware of hypotheses being tests as such.
Even congruence is problematic when it comes to molecular clocks. It's a
bit difficult to know the real nature of congruence here. Age estimates
that are more recent than a theorized geological event are said to be
'congruent' with later dispersal, but since they are only minimal
estimates they do not necessarily preclude an earlier origin so a later
clock estimate could still be said to be congruent with an earlier
geological event.

I see nothing necessarily creationist in asking what is the value of a
study that cannot reach a decision (although I notice that creationists
sometimes ask some really good questions that evolutionist propaganda
tends to ignore). It is not to say that there is no value.

John Grehan 

> -----Original Message-----
> From: Taxacom Discussion List [mailto:TAXACOM at LISTSERV.NHM.KU.EDU] On
> Behalf Of Thomas G. Lammers
> Sent: Monday, July 11, 2005 9:29 AM
> Subject: Re: [TAXACOM] Geological calibration of molecular clocks
> At 08:07 AM 7/11/2005, John Grehan wrote:
> >I have not read the entire article although I have seen the abstract.
> >Their concluding statement as cited by Robert is quite telling. If
> >is incongruence between two historical narratives (in this case the
> >geological story and the molecular clock story) and the authors
> >make up their mind between them what value is the study?
> "Value"?  Well, as a test of a hypothesis?  The geological story is a
> hypothesis, and we test it with the molecular clock story.  If we get
> congruence, we can accept the hypothesis; if we don't, we get more
> hypotheses and test them.  I *thought* that was how science works ...
> I must say,  that last sentence of yours sounds as though it was
> by
> a scientific creationist, the sort who expects every study to "prove"
> things conclusively and without doubt, so they can "believe" it or not
> "believe" it.  Maybe I'm wrong, but I just don't think that's how
> works.
> Thomas G. Lammers, Ph.D.
> Associate Professor and Curator of the Herbarium (OSH)
> Department of Biology and Microbiology
> University of Wisconsin Oshkosh
> Oshkosh, Wisconsin 54901-8640 USA
> e-mail:       lammers at
> phone:      920-424-1002
> fax:           920-424-1101
> Plant systematics; classification, nomenclature, evolution, and
> biogeography of the Campanulaceae s. lat.
> Webpages:
> -----------------------------------------------------------
> "Today's mighty oak is yesterday's nut that stood his ground."
>                                                                --
> Anonymous

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