HAM
Surname DNA Project
Research
through Genetics
Introduction to the
HAM Surname DNA Project
I
am pleased to welcome you to the HAM Surname DNA Project. It
is now possible to confirm a link where no conventional source records
exist.
Through
Y-DNA genetic sequencing, a painless cheek scraping is used to
obtain DNA that can help accurately
determine a relationship with either
a 99.9% probability of YES or a
100% certainty that no near term relationship existed. The
primary test attempts to determine if 2 people thought
to be unrelated actually had a common ancestor. A match is best
done by testing a known male member of your biological family, (brother,
father or first cousin), against the potential male relative.
With
appropriate analysis, we can now get a pretty good idea of who our
genetic ancestor was. One of our goals is to find the time to the
most
recent common ancestor. Scientists have calculated that
this is based on the observed number of mutations by which two Y
chromosomes differ. This is because mutations occur at random and can
provide a probability
distribution function.
The
approach for the HAM Surname DNA Project will be to group matching DNA
sequences and cross referencing that information against the oldest
known ancestor. My hope is that we can find more
conclusive evidence about the HAM immigrants and their countries of
origin.
Step
1
The first item to get done is to determine which samples belong to each
group, and which remain un-matched.
The easiest and quickest approach to do this is simply add the
sum of the differences between the values for each member.
The larger the value for the sum of the differences will indicate
the further away each group would be separated.
Step
2
As groups are found, they will be arranged together on the "results"
page. (The "results" page will be updated by matching groups.)
Step
3
When enough samples are gathered, other equations can be applied.
Usually, the serious work can be performed when we have at least 40
samples. Usually, this is when we
can start reliable calculations on the Most Recent Common Ancestor
(MRCA). Whom I can't help to think of but as "Mr.
Circa."
Over time, he should start looking like our first Paleo ancestor to
enter Europe.
Step
4
By this time, we should have a pretty good idea of how many HAM
immigrant lines have survived by repeating the iterations of
groupings. We also should begin to see these two items:
- Time to Most Recent Common Ancestor
- General location of the Most Recent Common
Ancestor by use of haplogroup studies.
With this step, I should be posting Phylogenetic graphs of the HAM DNA
Project data. (Phyletic is a reference to a name study.)
For
the more curious, the brief details:
The Y Chromosome has the unique feature
in that it causes a person to be male. And, the Y chromosome is only
transmitted from fathers to their sons. The Y Chromosome is virtually
identical through a number of generations over time. However, rare
mutations can occur.
Below is mostly
paraphrased from Bruce Walsh (2001-2002) Time to Most
Recent Common Ancestor -
The goal is to use
DNA sequences showing variation in the population (also called genetic
markers or simply markers); to provide information on how
closely the Y chromosomes from two individuals are related. Relatedness
is quantified by TMRCA, the Time to the Most Recent Common
Ancestor (MRCA), which is how many generations the two examined Y
chromosomes are from a common ancestor.
Estimates of TMRCA
are based on the observed number of mutations by which the two Y
chromosomes differ. Since mutations occur at random, the estimate of a
TMRCA is not an exact number (i.e., 7 generations), but rather a
probability distribution. As one uses more and more markers, the
distribution becomes tighter and tighter about its mean value (its
variance becomes smaller), and estimates have higher precision.
SNPs (pronounced
"Snips"
for Single Nucleotide Polymorphism's):
The problem with SNPs for genealogical work is that they
have very low mutation rates. This makes them very
useful for very deep genealogies (i.e. thousands of generations),
but not
helpful for genealogists because they are not recent enough.
A type of DNA
sequence called a microsatellite has a very high mutation
rate, so that it will only stay in its current state for a few
generations (with
mutations rates on the order of 1/500). Microsatellites are small
blocks of DNA with repeated sequences, for example ATATATAT is a
sequence with four AT repeats.
DYS# (DNA Y-Chromosome Segment marker number)
A
label for genetic markers on the Y chromosome. Each marker is
designated by a number, according to international conventions. At
present, virtually all the DYS
designations are given to STR
markers (Short Tandem Repeats - a microsatellite class
often used in genetic genealogy).
Generation
times:
All
times reported are usually generation times. One can translate these into years back to a
common relative by making assumptions about the average number of years
a standard human generation is. The values in the literature range from
15 to 25 years.
Mutation Rate Boundaries for the FTDNA
TMRCA Calculator:
1) Standard
-- assumes the mutation rate per marker u is u=1/500 = 0.002 . This is
the average of a number of studies. In other words, we can expect any
one marker to mutate once in 500 generations.
2) High -- u =
0.004. This places a lower bound on TMRCA, i.e.,
these times are likely UNDERestimates of the true times.
What
is the effect of adding even more markers?
Adding additional markers increases
the precision of the test.
-
Dave Hamm
HAM
Surname DNA Project Administrator
More
Information:
Time to Most
Recent Common Ancestry Calculator - by Bruce Walsh, University
of Arizona, FTDNA's Advisory Board
DNA 101 - From the BLAIR DNA
Project
Y
Chromosome DNA and the Y Line
- by Dr. Thomas Roderick, PhD, Center for Human Genetics. Article
posted to Ancestry.com about the role of the Y Chromosome in genealogy
studies.
The
Y Chromosome in the Study of Human Evolution, Migration, and Prehistory - by Neil Bradman and Mark
Thomas of the Centre for Genetic Anthropology with a discussion of the
Y
Chromosome
Haplogroups
of the World - Doug McDonald's Map
of the distribution of Y-DNA and
mtDNA