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Archiver > GENEALOGY-DNA > 2006-08 > 1154677738


From: "Alan Stanier" <>
Subject: Fast Markers
Date: Fri, 4 Aug 2006 08:48:58 +0100


Dear Ann

Thanks for clearing that up. Having read your archived posts, and about
FTDTATip, I believe the conclusion should be that if two people differ
*ONLY* on a fast marker, then the MRCA is likely to be slightly more distant
than if they differ only on a slow marker. And that does accord with my
intuition, as had there been sufficient time for a slow marker to mutate, I
would also expect at least one of the fast markers to have mutated as well.

Alan


Ann Turner wrote ...

>
> X-Message: #13
> Date: Thu, 3 Aug 2006 16:59:31 EDT
> From:
> To:
> Message-ID: <>
> Subject: Re: Fast markers (was: [DNA] research strategy for genealogists)
> Content-Type: text/plain; charset="US-ASCII"
>
> In a message dated 8/2/2006 4:56:40 PM Pacific Daylight Time,
> writes:
>
> > On Aug 2, 2006, at 10:40 AM, wrote:
> >
> > >1) Do the particular markers that differ put any weight on the
> > >relationship?
> > >
> > >No, the effect of fast versus slow markers is quite trivial
> > >compared to the
> > >absolute number of mutations, and it is the opposite of what
> > >intuition might
> > >tell us. If two people differ on fast markers, their common
> > >ancestor is slightly
> > >more distant than if they differ on slow markers.
> >
> > Since you took pains to point this out, I assume you meant it.
> >
> > The first part (the triviality of the difference) makes sense, and I
> > agree with it. I've only taken a few graduate-level statistics
> > classes, but nothing I've studied would suggest that the second part
> > (that differing on fast markers implies a more distant ancestor than
> > differing on slow markers) is true.
> >
> > If you don't mind me asking, what is the basis for this statement?
> >
> > Vince
>
> I wasn't at the FTDNA conference last November for Bruce Walsh's
> presentation
> on FTDNATip, but I understand he made that specific point. The
> mathematical
> proof is beyond me, but I've made attempts to verbalize the rationale and
> test
> some scenarios empirically at SMGF. These old posts are a sampling of
> messages
> I've written on the topic. (Long URLs, end in +F)
>
>
>
> http://listsearches.rootsweb.com/cgi-bin/ifetch2?/u1/textindices/G/GENEALOGY-DNA+2005+2304951381285+F
>
>
>
> http://listsearches.rootsweb.com/cgi-bin/ifetch2?/u1/textindices/G/GENEALOGY-DNA+2005+329769567+F
>
> Ann Turner
>
> ______________________________
>
>


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