GENEALOGY-DNA-L ArchivesArchiver > GENEALOGY-DNA > 2006-08 > 1156606941
Subject: Re: #7 Re: [DNA] `Ultra-Norse`..who is making up this stuff?
Date: Sat, 26 Aug 2006 11:42:21 EDT
In a message dated 8/26/2006 7:49:45 AM Pacific Daylight Time,
writes (to Ken Nordtvedt)
> Do you want to amend your claim that those present and accounted for today
> are not from specific groups who had an advantage in suvival (natural
> selection) including genetics?
> Subtext of below article, in Scandinavian populations gene indentified that
> offered immunity to Plague.
The CCR5 mutation is exceedingly interesting for studies of population
genetics. We've discussed it before on the mailing list -- probably the best term
for a search is CCR5* (where the * is a wild-card, so it will pick up some
synonyms for 32D in the link you gave, such as CCR5-delta32 or CCR5-del32).
Interestingly, the website has a graphic for CCR5-32D that shows gradients in
frequency ("clines"), which is exactly the sort of thing Ken is using for
studies of Haplogroup I. However, the CCR5 gene is located on chromosome 3, so it
has no bearing on the distribution of Y haplogroups. It will be distributed
in proportion to the frequency of the mutation and the frequency of the
For example, suppose 70% of the population is haplogroup I, and 30% is
haplogroup R1b. Suppose 20% of the population has the CCR5-32D mutation and 80% does
not. Then the "expected" distributions are
I and CCR5-32D = .7 times .2 = .14
I and CCR5 = .7 times .8 = .56
R1b and CCR5-32D = .3 times .2 = .06
R1b and CCR5 = .3 time .8 = .24
Now suppose a plague sweeps through a population of 1000, and only the
CCR5-32D survive. The survivors will be 140 men who happen to be haplogroup I, and
60 men who happen to be haplogroup R1b. That's exactly the same proportion as
before, 70% I and 30% R1b.
I put "expected" in quotes, because there is an element of randomness, which
is especially critical in small populations. In a population of 10, the
"expected" results would be 1.4 men in haplogroup I and .6 with haplogroup R1b,
which is absurd. The actual results might be one man in each group, and the
haplogroup frequencies would change to 50-50.