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From: "Malcolm Dodd" <>
Subject: RE: [DNA] Marker Mutation Rates
Date: Sun, 2 Nov 2003 11:20:40 -0000
In-Reply-To: <007a01c3a121$42402a80$7ee91e3e@ilbg18230>


Surely, a frequently changing marker could go +1 in one
generation and -1 the next. But why worry. It is the known
differences that are useful.

The point is that two sons of a father with a say 10 both mutate one to 9
and one to 11. Genealogists are told that there is a two-step difference and
are given a misleading time-frame.

Note that researchers are using the assumed mutation rate for their studies
and a recent report on the settlement date of America was calculated from
mutation rates as 18,000 years ago (rather than the probable date of 12,000
years ago).
Note that the immigrants would have been living on a sheet of ice 18,000
years ago so the result is highly unlikely.

My guess is that mutations are far more common than the industry is
currently assuming and that therefore the 23/25 match with a median
confidence interval of 28 generations or 560 years is substantially wrong.

The recent discussion under the heading of "Accuracy" mentioned the mutation
rate of multiple as opposed to single copy markers.
Could it be that multiple correct themselves during transmission more easily
than single copy markers? or vice versa?
Malcolm




-----Original Message-----
From: Ian & Mary Logan [mailto:]
Sent: domingo, 2 de Novembro de 2003 9:11
To:
Subject: Re: [DNA] Marker Mutation Rates


> Ron Lindsay, San Jose, CA started this thread and several people
have already joined in.

Hello Ron

Just a pennyworth ....

Some markers hardly ever, ever show 'mutations'. Why ?

A 'mutation' should be random - but clearly something affects
the rate. Might it be a 'spatial' effect with some parts of the
Y-chromosome being more protected, ie. spatially less
prominent, at the usual time of replication, and thereby less
prone to replication errors.

Other markers change from time to time, commonly +1,
probably a little less often by -1, and very occasionally
by +2 or -2.
And, in the odd case -3 seems to occur by preference
over +1, -1, +2 and -2 (how very strange!).

And, some markers change frequently - with perhaps some
of these changing just too often to be useful in genealogy.

FTDNA uses markers from each of these groups - which is
both interesting and useful.

Now back to one of your points ...
Surely, a frequently changing marker could go +1 in one
generation and -1 the next. But why worry. It is the known
differences that are useful.

Our little study at the Brooking Society
(see www.brookingsociety.org.uk should you wish)
is just one of the many one-name studies that is helping to find
the perfectly explained pedigree - and perhaps in time we will
understand everything better.

Comments anyone.

Ian




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