In a message dated 10/09/02 22:28:30 GMT Daylight Time, gma(a)bellsouth.net
writes:
I just got an email intended for Arthur. It is from a Mr. Art
Staple. It
seems he has the same DNA as a lot of our Cardens. I forwarded his email
to
Arthur.
I hope someone can help me. I think Arthur is still on vacation.
Hi, folks! I am back, after a bit of a delay - see PS at the foot of this
message.
Huge numbers of people with different surnames have identical DNA numbers.
This is partly due to the limited number of markers tested currently, and
FTDNA offer to test 25 markers rather than the 12 they normally test or the
10 tested by Oxford Ancestors. Far fewer people with different surnames
match on all 25 markers, and there is much debate on the GENEALOGY-DNA
mailing list at rootsweb as to whether these 25 marker tests are worth while.
Bear in mind that the Y-chromosome signature passed from father to son is
subject to mutations, and it is this that causes the differences between
signatures. If they didn't mutate everyone would have identical signatures!
Indeed the markers chosen for test are those that appear to have mutation
rates convenient for genealogical purposes.
The fundamental reason for matches is however that individuals with different
surnames may have a common ancestor before surnames began to be used, in the
12th century in England (and not until recently in, for instance, Iceland, I
believe).
It is conceivable that we all have a common ancestor if you go back far
enough. Professor Sykes in his "Seven Daughters of Eve" referring to the
mtDNA chromosome which is passed from female to female in the same way that
the Y-chromosome is passed from male to male, has satisfied himself that
there are only seven fundamentally different mtDNA signatures. A book well
worth reading.
Our basic "Cheshire Carden" Y-chromosome signature is shared by about one in
35 of all Europeans in a rapidly growing database for forensic purposes,
currently containing results of tests of over 10,000 males. We are only one
step away from what is called the Atlantic Modal Haplotype, the commonest of
all signatures (based on 7 markers).
People get very excited when they find their signature is identical with that
of someone else, and go to great efforts to discover genealogical links. In
my opinion this is meaningless most of the time, but as the above database
grows there is some indication that those with identical signatures may have
similar ethnic or regional backgrounds. But this is a bit doubtful at
present. It is not even clear whether for instance native-Americans tend to
have signatures which differ systematically from those of immigrants, or not.
For those with the same surname, of course, the identity of Y-chromosome
signatures is very significant. The double-match of surname and signature is
a highly significant indicator of a common ancestor.
If you want to know more about all this, join the GENEALOGY-DNA mailing list,
or have a look at Chris Pomery's splendid site -
http://freepages.genealogy.rootsweb.com/~allpoms/genetics.html
Arthur Carden, of Horsham, England.
PS. Got your message today on my return from a sailing holiday in France and
Spain - back a week late after a fire on board and loss of engine and
electricity in the middle of the Bay of Biscay. Great excitement! Sailed
for three days and nights with unfavourable winds until we got near enough to
a French port to get a tow in to a marina. It was really lovely steering by
the stars on a moonlit night even though not really in the right direction,
without benefit of electricity to light the compass (or work the satellite
navigation gear), merely a couple of hand torches to find our way about.