Relating to a group of people indigenous to a geographic region; the
original inhabitants of a region.
The "A" of the four bases that make up DNA. The other bases are thymine
(T), guanine (G) and cytosine (C). Adenine always pairs with thymine.
Of mixed ancestry or mixed origins.
Pronounced uh-leel, the allele value is the number of
times the sequence repeats in a
certain location. One of several forms of a
gene that can exist at a single location (marker) on a chromosome.
When STR's are measured on the Y-chromosome, this corresponds to a
different number of repeat units. For example, for DYS19 where
TAGA is the repeat unit, different alleles could be 13, 14, 15
repeats of the TAGA unit etc. A father will pass his Y-chromosome
on to his son and thus the son will inherit the same alleles (i.e.
no. of repeat units). Alleles will be changed if miscopied,
resulting in a mutation. Some alleles are more common in
See DNA amplification.
The oldest known or hypothesized haplotype for a particular lineage. See
also: modal haplotype.
The study of human origins, recent and distant, using DNA testing and
The study of humans, particularly in terms of origin and culture.
Modal Haplotype (AMH):
Also called the Western Atlantic Modal
(WAMH). The most common Y-DNA haplotypes found in Europe’s most
common Y-DNA haplogroup, R1b. As one
might expect the
AMH is the most common haplotype in Europe.
They are the following markers: DYS19 = 14, DYS388 = 12, DYS390 = 24, DYS391
DYS392 = 13, DYD393 = 13.
In my table these markers are located at
locus (location) 3-8-2-4-11-1. They may be placed at other locus
by different testing companys.
The non-sex chromosomes. Humans have 23 pairs of chromosomes: the first
22 pairs are autosomal DNA and the 23rd pair consists of the sex
chromosomes (the X- and Y- chromosomes).
Base The chemical unit
or building blocks of DNA. Named
Adenine (A), cytosine (C), guanine, (G), and thymine (T) are the four
bases in DNA.
pair up to form the "stairs" of the DNA double helix and always combine
in the same patterns: A with T and C with G. Two bases bonded
together and attached to one of the strands in the DNA double helix.
The DNA bases are always held together in pairs and attached to one of the
strands in the DNA double helix. The order of bases is the sequence of DNA.
A type of cell found in cheek tissue inside the mouth.
The smallest unit of living matter that can operate independently.
are bundles of tightly coiled DNA. Humans have 23 paired
chromosomes (22 pairs of autosomes and a single pair of sex
chromosomes). A single chromosome of each pair is passed from each
parent to child.
A structure found in the nucleus of a
cell that contains genetic material.
Cambridge Reference Sequence (CRS)
The mitochondrial DNA first sequenced in 1981 which is used as a basis
for comparison with mtDNA test results.
A substance which starts or speeds up a chemical reaction without being
affected by that reaction.
A region of DNA which contains genes.
Cohanim Modal Haplotype
The Y-DNA haplotype most commonly found among males with an oral
tradition of Cohen ancestry.
The Hebrew word for priest which refers to a direct male descendant of
Aaron, the brother of Moses; plural: Cohanim.
Combined DNA Index System (CODIS)
The CODIS system uses marker locations in the autosomal DNA. CODIS test
results are maintained in an FBI database which is used to identify
people and solve crimes.
Opposing strands of DNA which bond together to form the double helix.
The bases always complement one another with adenine and thymine pairing
together and cytosine and guanine pairing together.
The process of two unrelated or less related lineages changing over time
to resemble one another.
CRS (Cambridge Reference Sequence):
(mtDNA): The mitochondrion sequenced in 1981 became known as the Cambridge
Reference Sequence (CRS) and has been used as a basis for comparison with
your mtDNA. In other words, any place in your mtDNA where you have a
difference from the CRS is characterized as a difference or mutation.
(See also RSRS)
The "C" of the four bases that make up DNA. The other bases are adenine
(A), guanine (G), and thymine (T). Cytosine always pairs with guanine.
His work became the foundation of modern evolutionary theory. Charles
Darwin's 1859 book The Origin of Species promoted a theory of evolution
by natural selection and challenged Victorian-era ideas about the role
of humans in the universe. Darwin's theories were based on a constantly
evolving natural world and held that each generation of a species had to
compete for survival. Survivors held some natural advantages over their
unfortunate relatives and passed those characteristics on to their
progeny, thus over-representing these favored genetic types in the next
generation. Darwin also advanced the idea that species were descended
from a common ancestor. Darwin's work became the foundation of modern
Deletion: (mtDNA) A deletion takes place when a base pair is removed from
(Deoxyribonucleic Acid): The double helix-shaped molecule that holds an
organism's genetic information. DNA is composed of sugars, phosphates,
and four nucleotide bases: adenine, guanine, cytosine, and thymine (A,
G, C, T). The bases bind together in specific pairs (see detailed entry
below). A chemical consisting of a sequence of hundreds of
millions of nucleotides found in the nuclei of cells. It contains the
genetic information about an individual and is shaped like a
double-stranded helix. Known by many as the structure of
heredity, DNA is a chemical consisting of a sequence of hundreds of millions
of nucleotides found in the nucleus of cells. It contains the genetic
information about an individual and is shaped like a double-stranded helix.
Known by many as the structure of heredity, DNA is a chemical consisting of
a sequence of hundreds of millions of nucleotides found in the nucleus of
cells. It contains the genetic information about an individual and is shaped
like a double-stranded helix.
The production of many DNA copies from one or a few copies or fragments.
The process by which the DNA double helix makes a copy of itself or of a
fragment of itself. It uses the old DNA as a template for the synthesis
of new DNA strands. In humans, replication occurs in the cell nucleus.
The process of determining the exact order of the nucleotide bases in a
segment of DNA.
DNA Y-chromosome Segment (DYS)
The "name" of a marker on the Y-chromosome. It is assigned based on a
nomenclature system controlled by the HUGO Gene Nomenclature Committee,
which assigns DYS numbers to newly discovered markers.
Helix: The double
helix-shaped molecule holds an organism's genetic information. The
twisted shape of DNA, when its two strands bond together, much like a
spiral staircase or twisted ladder. The stairway's railings are composed
of sugars and phosphates. Its sides contain the patterned base pairs: A,
T, C, and G. When a cell divides for reproduction, the helix unwinds and
splits down the middle like a zipper in order to copy itself.
D = DNA: Y = Chromosome; S
= Single copy sequence. The DYS numbering scheme (e.g. DYS388,
DYS390) for the Y-STR haplotype markers are controlled and
administered by an international standards body called HUGO -
Human Gene Nomenclature Committee - based at University College,
A protein that facilitates a specific chemical reaction by working as a
Two individuals with exactly the same results for all markers or regions
DNA Time Predictor (FTDNATiPTM)
A program used to calculate estimates of Time to the Most Recent Common
Ancestor (TMRCA). It is the world's first calculator that incorporates
mutation rates specific to each marker. This greatly increases the power
and precision of estimates.
The first gene to be linked to language production, and the key to the
development of brain regions associated with speech. FOXP2's discovery
suggests that the development of language may be tied to a genetic
mutation that could have occurred some 50,000 years ago, in the same
time range as the first great human migrations out of Africa.
the functional and physical
unit of heredity passed from parent to offspring.
A segment of DNA which contains the genetic code to
make a certain protein or part of a protein.
Segments of DNA that are the basic functional units of heredity. Genes
are determined by an ordered sequence of chemical bases found in a
unique position on a specific chromosome. Their "blueprint" guides
protein production, which determines how different cells in the body
function. Inherited genes also control an animal's unique set of
Genealogical Data Communication
A type of file format used by genealogical software to make your family
tree. You can upload your GEDCOM file to your Family Tree DNA personal
page as well as Ysearch or mitosearch. Learn more about GEDCOM here
The study of family history.
The number of years between the birth of the parents and the birth of
their children. Different studies use different numbers of years per
generation. At Family Tree DNA we use 25 years.
Individuals whose Y-DNA or mtDNA test results match one another.
The number of differences, or mutations, between two sets of results. A
genetic distance of zero means there are no differences in the results
being compared against one another (exact match).
The study of genes and heredity; the study of DNA.
Random mutations in the DNA sequence which act as genetic milestones.
Once markers have been identified they can be traced back in time to
their origin—the most recent common ancestor of everyone who carries the
The total DNA sequence that serves as an instruction manual for all
proteins created in our body. Two copies of the genome are found inside
each of our cells. The entire complement of genetic material in a
chromosome set. The human genome is composed of 46 chromosomes, with a
total of 3 billion base pairs.
the actual alleles present in
an individual. Haplotype is a genotype of genetically
linked loci that are inherited in a block as a single unit. Modal
Haplotype (MH) Definition: any person who exactly matches the
alleles found to be most common (Modal) among the descendants of a
person. A person who matches 20 alleles while being 1 allele off
in only 1 locus will be considered to be in the haplogroup, rather
than in the family haplotype.
The scientific term for the peak of an ice age.
The "G" of the four bases that make up DNA. The other bases are adenine
(A), cytosine (C), and thymine (T). Guanine always pairs with cytosine.
Branches on the tree of early human migrations and genetic evolution.
Haplogroups are defined by genetic mutations or "markers" found in Y
chromosome and mtDNA testing. These markers link the members of a
haplogroup back to the marker's first appearance in the group's most
recent common ancestor. Haplogroups often have a geographic relation.
Haplogroups are large
groups that can be used to define genetic populations and are
often geographically orientated. For example, when the
Y-chromosome is tested, many males who live along the western
coasts of Europe belong to Haplogroup R1b (used to be called HG1),
which belies the historical movement of males along that coast.
The Y-chromosome haplogroup of an individual is
defined by their haplotype (because haplotypes are determined by
STR markers). Instead, they are determined by SNP's (single
nucleotide polymorphisms) where a single base changes e.g. from A
to G. These happen so rarely as to be considered unique.
However, there is a strong correlation between haplogroups and
haplotypes so given any particular haplotype, it may be possible
to correctly determine the haplogroup without any further tests
It is important to note that even
though female and male haplogroups may have the same letters, their
definitions are different.
The matches listed on your personal Haplotree Matches page are
determined by comparing your first 12 markers, not your SNPs. So
the Haplotree Matches page is saying that you have two exact 12-marker
matches who have done SNP testing to determine their haplogroups -- one may
be R1b1a2a1a1b3 and the other may be R1b1a2a1a1b5a. This page is
intended to give you a general idea about what your haplogroup might be,
based on a 12-marker comparison with your matches. However, since 12-marker
matches are extremely broad, it's definitely possible (and even common) at
that level for your matches to be in different subclades than you, as is the
Your Y-DNA haplotype is a
set of 21 numbers (if using 21 STR markers), each number
representing your allele at a given STR marker. Two or more
haplotypes may be compared as a check for a genetic relationship.
Two individuals that match exactly on all markers
have the same haplotype.
There are many haplotypes to be found from many different
populations around the globe at
www.yhrd.org that may be used to compare haplotypes. Also, the
Ybase database can accept genealogical as well as haplotype
N1 This haplogroup is distributed throughout Northern Eurasia. It is the
most common Y-chromosome type in Uralic speakers (Finns and Native
Siberian). This lineage most likely originated in northern China or Mongolia
and then spread into Siberia where it became a very common line in western
R1 The undifferentiated R1 lineage is quite rare. It is found only at very
low frequencies in Europe, Central Asia, and South Asia. This lineage
possibly originated in Europe and then migrated east into Asia.
R1b Haplogroup R1b is the most common haplogroup in European populations.
It is believed to have expanded throughout Europe as humans re-colonized
after the last glacial maximum 10-12 thousand years ago. This lineage is
also the haplogroup containing the Atlantic modal haplotype.
R1b1 This lineage is also the haplogroup containing the Atlantic modal
R1b1b2 This lineage is also the haplogroup containing the Atlantic modal
R1b1b2d Its branch R1b1b2d is found primarily in the British Isles, but can
also be found at lower frequencies around Western Europe.
R1b1b2e Its branch R1b1b2e is primarily found in Northern Ireland, and
contains the Niall Modal Haplotype.
R1b1b2g Its branch R1b1b2g is distributed across Europe.
R1b1b2h Its branch R1b1b2h is distributed across Europe.
All Contents Copyright 2001-2007 Genealogy by Genetics, Ltd.
A measure of the uniqueness
of a particular haplotype in a given population.
The total sum of genetic information that humans pass on from generation
to generation. The transmission of genetic material from parents
Human Genome Organization (HUGO)
The entity to which, among other things, scientists submit new markers
for DYS number assignment.
HVR1 and HVR2
(HyperVariable Region 1 and 2): The two sections or regions of the mtDNA
which are tested in the mtDNAPlus test. The results can be used to determine
a person’s ethnic and geographic origins, as well as to look for possible
common ancestry with other individuals.
Hypervariable Region (HVR)
One of two regions commonly used in mitochondrial DNA tests which does
not code for any known function.
1. What are the parts of the
mitochondrial DNA (mtDNA)? FTDNA faq id: 483
Mitochondrial DNA (mtDNA) has two major parts, the
control region and the coding region.
The control region is often called the hypervariable region (HVR).
Hypervariable means fast changing. In mitochondrial DNA the control region
is the fast changing part.
2. What are HVR1 and HVR2?
The control region may be further
divided into two Hypervariable regions, HVR1 and HVR2.
HVR1 runs from nucleotide 16001 to nucleotide 16569.
HVR2 runs from nucleotide 00001 to nucleotide 00574.
3. What is the Coding Region?
The coding region (CR) is the part
of your mtDNA genome that contains genes.
Because it does contain some genes, the coding region is believed to be
slower mutating than the control region. Often, it is the
mutations that are found in the coding region that are used to define
haplogroups. The coding region runs from nucleotide 00575 to
4. What are "low resolution
matches"? FTDNA faq id: 484
An exact match on the first hypervariable region, HVR1, is sometimes called
a low resolution match. When the match also shares the same haplogroup
it indicates a possible connection. An HVR1 match has a 50% chance of a
common maternal ancestor within the last fifty-two generations or about
When an HVR1 match belongs to a
different haplogroup it is due to convergent evolution. That is when by
coincidence two different lineages mutate to look alike. [This seems
to be saying to compare HVR1 and HVR2 only within your Haplogroup].
5. What are "high resolution
matches"? FTDNA faq id: 485
An exact match on both the first and second hypervariable regions, HVR1 and
HVR2, is sometimes called a high resolution match. When they also share the
same haplogroup it indicates a possible connection. A match on
HVR1 and HVR2 means that you have a 50% chance of a common maternal ancestor
within the last twenty-eight generations or about 700 years.
When they have different haplogroups
it is due to convergent evolution. That is when by coincidence two different
lineages mutate to look alike. [This seems to be saying to
compare HVR1 and HVR2 only within your Haplogroup].
6. How many generations back does
mitochondrial DNA (mtDNA) testing trace? FTDNA faq id: 486
Mitochondrial DNA (mtDNA) testing covers both recent and distant
generations. To find connections in recent times it is necessary
to find and test multiple people who have suspected shared ancestry.
This is done by careful examination of traditional genealogical records.
Making connections with people in genealogical and historic interest groups
can also be helpful.
Matching on the Mitochondrial DNA
Full Genomic Sequence (FGS) test brings your matches into more recent times.
It means that you have a 50% chance of sharing a common maternal ancestor
within the last 5 generations. That is about 125 years.
Mitochondrial DNA testing at Family Tree DNA also includes haplogroup
testing. Your haplogroup represents your ancestral origins thousands to tens
of thousands of years ago.
7. Why do I have so many
mitochondrial DNA (mtDNA) test matches? FTDNA faq id: 489
There are some result haplotypes that show a high number of matches. There
are two possible explanations for this.
a. Many people with the same results as your ancestors lived thousands or
tens of thousands of years ago. The majority of their descendants still
carry their signature.
b. A more recent common ancestor — within the last one or two thousand years
— with this haplotype had many daughters who in turn had many daughters and
so on leading to you having many distant cousins.
8. Increasing your testing level to
the Mitochondrial DNA Full Genomic Sequence (FGS), the "HVR1toMega" or the
"HVR2toMega upgrade", will separate these two cases. This will allow you to
focus on your relevant matches.
Insertion: An insertion takes place when a base pair is added to the
Stretches of DNA that do not code for genes, also called non-coding DNA.
Most of the genome consists of non-coding DNA, and was therefore long
thought to be 'junk.' Scientists have found that in addition to
containing markers that are helpful for genetic genealogy, parts of
these non-coding regions have regulatory and other functions.
Golssary at FTDNA web site
The plural of locus, or marker. Locus and loci are Latin words
(plural-loci) Latin for place.
A specific spot
in the genome. A variable locus will have several possible
alleles. See marker.
Also called a Locus (pl.
loci). A gene of a known location on a chromosome. See STR marker.
The DNA Heritage Y-DNA test uses 21 STR markers.
Family Tree DNA offers 3 levels
of Y-DNA testing: 12-marker, 37-marker, and 67-marker.
The stage in which sperm and egg cells are formed. It is during this
process that the autosomal chromosomes recombine and mutations occur.
Melanin/Vitamin D/Skin Color: Melanin, the skin's
brown pigment, is a natural sunscreen that protects tropical peoples
from the many harmful effects of ultraviolet (UV) rays. But when UV rays
penetrate the skin they also produce beneficial vitamin D, so some
exposure to them is necessary. This delicate balancing act explains why
the peoples that migrated to darker, colder climes also developed
lighter skin color. As people moved to areas with lower UV levels, their
skin lightened so that UV rays could penetrate and produce essential
vitamin D. In some cases a third factor intervened. Coastal peoples who
eat diets rich in seafood enjoy an alternate source of vitamin D. That
means that some Arctic peoples, for example, can afford to remain
dark-skinned even in low UV climes.
See short tandem repeat.
Mitochondria: A remnant of an ancient parasitic
bacteria that now helps to produce energy inside the cell. A
mitochondrion has its own genome, present in only one copy, which does
not recombine in reproduction. This genetic consistency makes
mitochondrial DNA a very important tool in tracking genetic histories.
A specific organelle in the cell that helps it to produce energy.
Mitochondrial DNA or mtDNA:
The genetic material
found in the mitochondria. It is passed from females to their offspring
without recombining, and thus is an important tool for geneticists.
It is passed down from females to both sons and daughters, but sons do
not pass down their mother's mtDNA to their children.
comes from the statistical
term Mode, which means the value at which an absolute or maximum
occurs in the frequency distribution of the variant.
The most common result for each marker tested in a group of results. See
also: ancestral signature.
Associations of the R Haplotypes
Most Recent Common Ancestor
The ancestor shared most recently between two individuals.
mtDNA is passed down from females to both son and daughter, but sons do not
pass down their mother’s mtDNA.
A heritable change that occurs in genetic material. It may lead to a
different number of repeats of a certain sequence or a change in one of
the bases in a sequence. A heritable change that may occur in a
gene or in a chromosome and may take the form of a chemical rearrangement or
a partial loss or gain of genetic material.
The frequency with which random mutations occur.
A DNA building block which contains a base, or half of a "staircase
step," and sugars and phosphates which form the "railing." Nucleotides
join together to form DNA's distinctive double helix shape. A
piece of DNA that contains one base, one phosphate group, and one sugar
unit. Thousands of nucleotides joined in sequence make a molecule of
The part of the cell in which chromosomes reside. The
membrane-bound organelle containing the chromosomes.
For STRs, a plot which shows the length of a fragment of DNA. This
allows its allele value to be measured.
Phylogeny: The evolutionary development of a
species. Phylogeny is sometimes represented as a tree that shows the
natural relations and development of all species.
Point Mutation a
change in a single base pair.
Population genetics: The study of genetic
variation in a species.
Proteins: Linear sequences of amino acids that
are the building blocks of cells. Each protein has a specific function
that is determined by the "blueprint" stored in DNA.
See Y-DNA phylogenetic tree.
The enzyme that starts the process of making nucleic acids or assembling
RNA or DNA.
Polymerase Chain Reaction (PCR)
A technique allowing the production of multiple copies of extremely
small amounts of DNA fragments using DNA polymerase and specific
A mutation, or change, in the DNA sequence which is inheritable.
A short DNA sequence used in the polymerase chain reaction to initiate
DNA synthesis at a particular location.
The main building block of our cells. Each one has a specific function.
Recombination: The process by which each parent
contributes half of an offspring's DNA, creating an entirely new genetic
identity. This process mixes genetic signals, so that nonrecombining
DNA, passed intact through the generations, is most important to
population genetics. An event occurring during meiosis - the
formation of sperm and egg cells. One chromosome from the mother and the
other from the father break and trade segments with one another.
Replication: The process by which two DNA strands
separate, with each helping to duplicate a new strand. During
reproduction, the DNA double helix unwinds and duplicates itself to pass
on genetic information to the next generation. Because bases always form
established pairs (AT and CG), the sequence of bases on each strand will
attract a corresponding match of new bases. Only occasional errors
occur—about one for every billion base-pair replications. See DNA
(Ribonucleic Acid): Transfers the genetic
"blueprint" that is stored in DNA during protein production. RNA has a
single-stranded linear structure and a slightly different chemical
composition from DNA.
A protein that recognizes a certain sequence of DNA and cuts the DNA at
Restriction Fragment Length Polymorphism (RFLP)
See single nucleotide polymorphism.
Sapiens Reference Sequence): Family Tree DNA is staying on top of
the latest advancements in genetic genealogy, adding a new way of reporting
our mitochondrial DNA. In April of this year a paper by Doron
Behar (et al) was published proposing a new method of reporting mtDNA. This
new method uses mutations referenced to a Reconstructed Sapiens Reference
Sequence (RSRS) instead of the traditional revised Cambridge Reference
In this study, we
propose a “Copernican” reassessment of the human mtDNA phylogeny by
switching to a Reconstructed Sapiens Reference Sequence (RSRS) as the
phylogenetically valid reference point. The aim is to trigger the radical
but necessary change in the way mtDNA mutations are reported relative to
their ancestral/derived status, thus establishing an intellectual
cohesiveness with the current consensus of shared common ancestry of all
contemporary human mitochondrial genomes. Posted 4/3/2013 - Reference
Sequencing: Determines the order of nucleotides
for any particular DNA segment or gene. The order of a DNA string's base
pairs determines which proteins are produced, and thus the function of a
particular cell. See DNA sequencing.
The X- or Y-chromosome. Normally males have one X and one Y and females
have two Xs.
Selection: Special form of natural selection
based on an organism's ability to mate. Some animals possess
characteristics that are more attractive to potential mates, such as the
distinctive plumage of some male birds. Individuals with such
characteristics mate at higher rates than those without, ensuring more
next generation offspring will inherit the desirable trait. As
generations procreate the desirable trait becomes increasingly common,
further boosting the sexual disadvantage for individuals who lack the
desired trait. The effect can be particularly dramatic when one
individual controls mating with a large number of potential partners.
Short Tandem Repeat (STR)
A short DNA motif (pattern) repeated in tandem. ATGC repeated eleven
times would give the marker a value or allele of 11.
Nucleotide Polymorphism: Small, infrequent
changes which help to create an individual's own unique DNA pattern.
When a single nucleotide (A, T, G, or C) in the genome sequence is
altered during DNA replication, due to a tiny "spelling mistake," the
genome sequence is altered. A person has many SNPs that together
create a unique DNA pattern for that individual.
SNP tests are able to trace
both ancient anthropological migrations and more recent prehistoric
movements. A Y-DNA SNP test also identifies the haplogroup, which
represents your deep ancestral origins (tens of thousands of years ago).
STR (Short Tandem
Repeat) A region of repetitive DNA with short units of repetition
(2 to 6 basis). STR tests are able to trace a male lineage
within genealogical times and into historic times. Your genealogical
connections will be shown on the Y-DNA – Matches page of your myFTDNA
account. The Y-DNA – Ancestral Origins page of your myFTDNA account
will point towards possible countries of origin.*
A last name or family name traditionally passed down from father to son.
The "T" of the four bases that make up DNA. The other bases are adenine
(A), cytosine (C), and guanine (G). Thymine always pairs with adenine.
Time to the Most Recent Common Ancestor (TMRCA)
The amount of time or number of generations since individuals have
shared a common ancestor. Since mutations occur at random, the estimate
of the TMRCA is not an exact number (i.e., 7 generations), but rather a
probability distribution. As more information is compared, the TMRCA
estimate becomes more refined.
this term used by population
geneticists indicates the Time to the Most Recent
Common Ancestor shared with another person.
The physical characteristics, like eye color or nose shape, which are
determined by inherited genes.
The passage of genetic material from one generation to the next.
Unique Event Polymorphism (UEP)
See single nucleotide polymorphism.
Western Atlantic Modal
The most common Y-DNA haplotypes found in Europe’s most common Y-DNA
X and Y
Chromosomes: Chromosomes which determine sex.
Females have two X chromosomes while males have one X and one Y. When
chromosomes pair, the mismatched Y determines male gender. Because of
the mismatch, part of the Y chromosome does not recombine with the X
during reproduction. The nonrecombining part of the Y chromosome
contains a sequence of DNA passed intact from males to their sons
through the generations, giving population geneticists a useful tool for
studying human history. The Y-chromosome passes down from father
to son. Females do not receive it. The fact that the Y-chromosome goes
down the paternal line makes it valuable for genealogy studies, since it
typically follows a surname line.
The sex chromosome that
instructs a foetus to grow into a baby boy. It is passed down from
generation to generation only through the male line i.e. from
father to son, father to son, etc. It is approx. 60 million
non-recombining DNA determines
whether a child will be a male or female. Y-DNA passes from father
to son almost unaltered for long periods of time.
Y-DNA phylogenetic tree
A graphic representation of the Y-DNA haplogroups according to the YCC
classification. Haplogroup names and major clades are labeled and
mutation names are given along the branches of the trees.
When comparing the results of Y-Chromosome STR (short tandem repeat) tests,
the difference between the two values at a marker is the Y-DNA genetic
distance or the step-mutation count. That is, a one-step mutation means that
the count for a single STR has changed by one. A two-step mutation means
that the count for a single STR has changed by two