Could have tackled
this topic right off the bat during "D" as in DNA, but didn't.
DNA is the new kid
on the block in genealogy. It's even
more exciting than the next census.
Ancestry.com started DNA in 1983, according to Google.
I say at the outset
that while I understand how the three tests work - autosomal, mitochondrial and
Y-chromosome - I have yet to get excited about DNA, though I know lots of
people who are very excited, and spending lots of time learning how to
construct the science, especially that of autosomal DNA comparisons.
I will say that in
the last 2 months I have heard info that leads me to be a bit more interested in
autosomal, and I join those who are glad there may be another avenue for cold
cases, but so far, the DNA tests that truly intrigue me are mitochondrial and
Y-chromosome.
Quick review:
Mitochondrial DNA,
the 'x' chromosome, is passed mother to
daughter to daughter to daughter… etc., though the last generation can be
either daughter or son.
The
incredible thing about the 'x' chromosome is that unlike most of DNA, it does
not combine and divide with each child and generation. It remains, being passed from generation and
eon to eon as it is. Rarely, very very
rarely, there is a mutation, and then that mutation stays for the next several
eons.
The same is true for
the Y-chromosome, the male chromosome, which is passed father to son to
son…etc., and ONLY to sons, so even the last generation must be male.
Repeat: The incredible thing about the 'x' chromosome
is that unlike most of DNA, it does not combine and divide with each child and
generation. It remains, being passed
from generation and eon to eon as it is.
Rarely, very very rarely, there is a mutation, and then that mutation
stays for the next several eons.
We talk about lines
"daughtering out" with reference to the disappearance of the last
name, but the Y-chromosome can just as easily daughter out. Likewise, a family line of all sons ends
that line for the X-chromosome.
Looking ahead:
What intrigues me is the vast reaches of time that these two DNA
tests, Mitochondrial and Y-chromosome,
have the capability of bridging. My
"Ross" is presumed to come from Scotland, either directly, or by way
of Ireland. The earliest fixed date in
the US is 1824/25 figured from the age Patrick Ross gave on his enlistment in
1861 for the Civil War. Given that he
was born in Knox, Tenn, I hold small hope of finding paper to carry him
back. I hold small hope that the
Y-chromosome test taken by my brother will link with someone in UK, but after
years of searching for paper and finding nothing, my small hope of a DNA link
to UK is slightly bigger than my small hope of finding paper.
Three companies do
autosomal tests; one does X & Y.
Have a look and save your pennies.
Till next time,
Liz
+++++++++++++++++++++++++
2018
begins with an "ABC-darium," a walk through the alphabet expanding
into short comments on matters genealogical. Published on most Tuesdays
and some Fridays, a letter may be visited more than once before moving
on.
©
2018, SE Ross