Members of the
G group are all descended from a common ancestor who developed a mutation at
the M-201 site on the male DNA chromosome (Y chromosome). This
man who developed this mutation was living at that time with men who
carried in their Y-chromosomes the predecessor mutation to haplogroups F
through R — most of the haplogroups that now exist. The man who
developed by chance the M-201 mutation would not
know that anything was different, and it probably took some time
before the descendants of this M-201 man dispersed
to different locales.
In one of the original descriptions,
author Spencer Wells indicate this M-201 ancestor lived about
30,000 years ago along the eastern edge of the Middle East, perhaps as far
east as the Himalayan foothills in Pakistan or India. This
region is the proposed site, but little evidence of this precise location as
the site is available. In a different version of the origin of
G, it is listed as happening 9,500 years
ago
in the Middle East in an article from 2003 by Cinnioglu (p. 184 iii). Another version by Semino in 2000 suggested
it was 17,000 years ago in the Middle East. The National Geographic
Society DNA Project, with which Spencer Wells is affiliated, in summer 2006
changed the place of origin of G to
the Middle East. The 2007
pre-publication of the Y-Chromosome Consortium (YCC) changed its
prediction as to origin of G as 20,000
years before present.
Most of these figures of
30,000 or 17,000 or 9,500 years ago should not be given too much
credence.
Those who cite such figures in
time base their calculations on the number of STR mutations separating men
with different haplogroups and the supposed average number of generations it
takes for a mutation to happen. Since both deletions and additions to
STRs occur, it can be difficult to determine the number of mutations when an
addition is lost at a particular site ... OR... a deletion is replaced by an addition at the same site. And
a few STR mutations are bizarre changes of, for example, 6 or 7
values. The YCC had a large number of STR markers available for the
first time, including slow markers. So perhaps the large number of
markers have allowed them to overcome some of these problems of using only a small number of markers in
earlier studies.
There is another scientific method which can
determine the minimum age of a mutation, such as M-201. This method has
the potential of validating or invalidating the method currently used
to calculate ages of haplogroup mutations. In this alternative method
of dating, an ancient skull is obtained, and teeth are submitted for DNA
testing. At the same time, testing is done to determine reliably the
age of the skeleton. For example, if the M-201 mutation should be found to
exist in the ancient DNA, if can be assumed that the M-201 mutation is at
least as old as the skeleton.
There has not been much testing of ancient
male skeletons for Y-chromosome DNA. Some skeletons do not have viable
DNA. In addition, some of the earlier work done in this field
is suspect, and the results may represent the researcher's DNA or damaged
DNA. Early in 2007, a study
of an Alaskan skeleton dated to 10,300 years ago, used a promising
methodology. In the approach used, different teeth were sent to different
labs, and other stringent precautions were taken, such as coding the DNA
of those handling the samples.
Unfortunately, it does not appear that any
researcher has yet obtained DNA results from Y-chromosome DNA in an
ancient haplogroup G individual.
While avoiding the dating of the M201 mutation, I have made
available on the clade page at this site an estimate of the periods in which
some of the G subgroup mutations arose and when a few clades arose.
These estimates are much more recent than the 20,000 yrs B.P. estimate by the
YCC for general G (M201) and based on 37 STR markers.
Whatever the date or specific site of origin, part of the
G family put down roots predominantly in the area south and
east of the Caucasus Mountains in the period before the Current Era (over
2000 years ago) when some other groups were instead populating all areas of
Europe for the first time after the Ice Age glaciers
melted. These G persons gradually relocated into other areas,
including the Indian subcontinent. The Caucasus are today mainly the
countries of Georgia, Armenia, Azerbaijan
and southwestern Russia. Map of countries and groups in the
Caucasus Two studies by the same
author found the highest local percentages of G among the
Caucasus population were on the Russian
side of the mountains,
reaching more than half the population in North Ossetia. Study of DNA
groups in the Caucasus
It is assumed the G people were in the Caucasus area in this
early period because today a higher percentage of G haplogroup is found
among certain populations there than elsewhere in the
world. The G family definitely partially migrated westward into
Europe in the last several thousand years by invasion, capture as
slaves or other means of movement. Some may have come
earlier. Map of haplogroups today in the world
[a map of Europe alone is below the one shown on
entering the site]