GENEALOGY-DNA-L Archives

From:
Subject: Re: [DNA] How can scientists tell which mtDNA comes from N. or S. Europe?
Date: Fri, 1 Aug 2003 09:02:53 EDT

In a message dated 07/31/03 2:38:50 PM Pacific Daylight Time,
writes:

> How do scientists discern which mtDNA comes from northern or southern
> Europe? It's obvious that J mtDNA originates in Syria/Levant/Anatolia, but
> what about H, K, T? We know that V probably originated in Spain 13,000 years
>
> ago and migrated to both N. Africa and Scandinavia, and that U5 originated
> in Europe and was first found in Delphi, Greece, assumed to be there 45,000
> years ago, but how do scientists tell which markers are N. European and
> which are S. European, other than the text of oxygen isotopes in teeth? What
>
> other markers signal origin north or south of which particular "Mason-Dixon"
>
> Line in Europe? Any info welcome.

As JBOURGEO noted, the seven major European mtDNA haplogroups probably
originated in the southern parts of Europe. There's a rather nice map at Oxford
Ancestors, showing Europe in the last Ice Age and possible points of origins for
the haplogroups:

http://www.oxfordancestors.com/images/AncientMap.pdf

Scientists deduce the points of origin based on sampling current residents,
obviously a very fuzzy process. They look for two main clues: the concentration
of haplogroups and the number of variations found in different locations.

The reasoning goes like this: the woman who had the mutation defining a new
haplogroup lived in a specific location. She had many descendants who remained
in the area, so the concentration remains high. But a few descendants began to
migrate and spread themselves thinly in different directions. Each of those
migrants has to start from scratch accumulating descendants, so the
concentration remains low. If you see gradations of frequency (called "clines"), then the
most concentrated area is probably the point of origin. Obviously there are
exceptions -- if a migrant moves to an unpopulated area, she will be a
"founder" and her descendants will be a very high concentration.

The second clue is how many variations in the HyperVariable Regions (HVR1 and
HVR2) have accumulated since the defining mutation in the coding region. The
descendants who remained in the location will show lots of different patterns,
but the migrants to outlying regions will have just a few. And if a few
thousand years have passed, the migrants will begin to show mutations which aren't
found at the point of origin. Accumulating mutations is a rather slow process
compared to migration rates, so this is a fuzzy method, too.

All the theories and calculations are based on a rather small amount of data,
but the broad picture will probably hold up.

I am at a complete loss as to how you are relating oxygen isotopes in the
teeth to mtDNA haplogroups.

Ann Turner - GENEALOGY-DNA List Administrator
Search or Browse the archives, Subscribe or Unsubscribe at
>http://lists.rootsweb.com/index/other/Miscellaneous/GENEALOGY-DNA.html
DNA preservation kits: http://www.dnafiler.com

This thread:

• Re: [DNA] How can scientists tell which mtDNA comes from N. or S. Europe? by

  • Re: [DNA] How can scientists tell which mtDNA comes from N. or S. Europe? by
    • Re: [DNA] How can scientists tell which mtDNA comes from N. or S. Europe? by "Mary AsaWoman" <>