| When You Really Want to Know, the Y Chromosome May Hold the Answer | |
As a species, we have always been fascinated with the history of our ancestry.
Genealogy, the study of our family ancestry, is no longer the hobby of the
social elite. It is now a national pastime. With the advent of the Internet,
genealogy has become firmly established as a focal point within American
society. There are hundreds of Web sites on thousands of families, all offering
information to those interested in tackling their family's roots. However, as one
becomes involved in a search of the family history, the process can become
daunting. The written, oral, and photographic history of a family may at times
provide only clues to its ancestry. Fortunately, a new technology is available
which can provide real answers. A spin-off of the Human Genome Project, Y chromosome
testing has proven very
useful as a tool for genealogy research. Y chromosome studies have been performed
on populations from around the world to evaluate the relationships between
ethnic groups and closely related families. The human species has 23 pairs of
chromosomes, 22 which appear the same, and the x and y chromosomes. If you are a
male, you have the standard 22 pairs, plus one x and one y chromosome. If you
are a female, you will have the standard 22 pairs, plus two x chromosomes.
Chromosomes contain the genetic code that determine our physical appearance and
how we function as a living being. The genetic code is contained within a
molecule commonly referred to as DNA (deoxyribonucleic acid). In the 1980's
scientists discovered that the genetic code contained within chromosomes does
not always direct the synthesis of cell products, but contained highly variable
regions of "nonsense" DNA. It was later discovered that these regions
could be used as markers for the identification of individuals. The use of these
DNA markers in criminal forensics is common throughout the world today. The Y chromosome, like the other 22 pairs within the cell, also contains
non-coding variable regions of DNA. These regions have been rigorously studied
and the data generated has proven extremely useful in population studies. It has
been discovered that there is significant variability within the polymorphic
regions of the Y chromosome between populations, but there is little or no
variability between father and son. The Human Genome Project has given us an
invaluable tool for the verification of male lineage. Probably the most famous case to date has been the verification of male
lineage among the descendents of Thomas Jefferson and Sally Hemmings. Y
chromosome testing has revealed that "a" Jefferson was most likely the
father of Sally Hemmings youngest son, Eston Hemmings. Studies of the Y
chromosome have also been used to study the male lineage of U.S. Supreme Court
Justice John Marshall Harlan. Y chromosome studies are performed on blood samples collected from suspected
family males. The DNA is extracted from the cells and specific regions of the Y
chromosome are targeted for analysis. These regions are subjected to a process
call the polymerase chain reaction (PCR), which produces thousands of copies of
the target DNA. These copies are then sorted and analyzed. The data generated by
this process will either confirm or deny the suspected common male lineage
between the samples. Y chromosome testing is not paternity testing, as it relies
only on the analysis of the male DNA. Many times in the process of searching through our family histories, we reach
points where assumptions have been made regarding the family lineage. The
presence of "indiscretions" within a family may be omitted or
covered-up, depending on the era when they occurred. Recent studies that we have
participated in have both verified and denied male lineage. However, when you
really want to know, Y chromosome testing may be the best new technology
available to answer that question. Related Resources: Molecular Genealogy: Can DNA
Replace Lost Family Records Genetic Genealogy Links Famous Genealogies Basic
Genetics
The Molecular Genealogy Research Group is working to build a database of genetic
family trees which will eventually enable people with blocked genealogies such
as adoptions, illegitimacies or missing records to trace their origins.
The field of molecular genealogy (genetic genealogy) is fairly new and growing
fast. These sites will help you learn how the genetic markers in DNA can help
you to find your ancestors.
Fun and fascinating family trees including royalty, nobility, presidents, famous
historical figures, famous women, Greek and Roman gods, and a variety of
fictional characters from books and television.
Find out about the history of genetics-related research, basic concepts
in genetics and the relationship between genetics and disease from Genetics
Guide, Laura L. Jelliffe, Ph.D.
