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Autosomal DNA Testing
Testing to Address Genealogical
Questions
Written by Roberta Estes, www.dnaexplain.com,
Copyright 2007-2009 Contact information: [email protected]
Most of us can
determine quite easily by looking in the mirror the identity of our majority
ancestry. Even those recently
admixed can see compelling physical evidence of their heritage.
Scientists tell us that 25% or more admixture from any particular ethnic
group will show in physical traits. I originally wrote
this paper for those who are searching both genealogically and genetically for
their Native American ancestors and heritage.
However, the concepts are sound for those searching for any minority
ethnic heritage, those who are just curious as to whether they carry minority
heritage or those who simply want to know how autosomal DNA testing works. In American
history, unfortunately, the records pertaining to Native Americans and sometimes
African Americans as well are nonexistent, disguised or buried in some other
obscure record. In the case of
Native Americans, those who were “reservation Indians” we’re taxed and
therefore we have absolutely no record of their existence.
There were no individual land records since the reservation was held as a
“tribe” and those who moved off of the reservation were often exceedingly
poor, very marginalized and practiced subsistence living either wholly or in
part. Many did not adopt European
last names until they had no choice. Free people of
color who are identified as being Indian, African or mulatto which meant any
admixture of Indian/European, African/European or Indian/African, were prevented
from voting, testifying in court and attending white schools.
They owned land much less often than their counterparts of European
descent. Most often, these people
were sharecroppers, often less fortunate than slaves who were at lest provided
with food and shelter. They were
desperately poor, hungry and barely surviving.
Poor white sharecroppers often worked side by side with free people of
color, both attempting to scratch a living from their marginalized
circumstances. Without tax, deed,
court or other records, the genealogist often reaches a dead end.
Unfortunately, money was required for all of these transactions,
including obtaining a marriage license, which probably explains many missing
records. We find court
records in the NC general assembly sessions where the desperately poor weren’t
being taxed because they had nothing, but the tax collectors were instructed to
collect poll taxes for them from the land owners on which they lived.
Many probably lost their homes because of this legislation.
Enslaved Africans,
Indians and many Europeans who were brought as indentured servants lived and
worked together. Most indentured
servants served 7 years, some more and a few less.
Masters tended to work indentured servants harder, with less rest, and
more brutally than their slaves that they owned. They knew that with indentured servants, they would only have
the benefit of 7 years labor and they intended to get every hour of every day
from them. Many died. During the time of
the European’s indenture, they often lived and worked in the slave population
on the plantation. Nature taking
its course, these populations, African, Indian and European established
relationships and had children. Eventually
laws were enacted prohibiting whites from intermarrying with people of color,
free or bond, but that didn’t stop nature from taking its course.
Owners of slaves
who were bond for life tended to treat them somewhat more humanely than
indentured servants, if the circumstances under which slaves lived can be
described in that manner at all, because they had a financial investment in
their continued health. A sick or
dead slave was worth nothing or worse, was a liability. Indian and African
slaves were generally not viewed or recorded differently. In the 1600s and early 1700s we occasionally find a reference
to “Indian John” or “my Indian man”, although seldom anything that
identifies anything more about the individual or his family. Later records show no differentiation at all.
Of course, as Indian populations were depleted and African slaves were
imported in increasing numbers, there were no new Indian slaves and those
already enslaved married with whomever was available on the plantation (or the
neighbor’s plantation) and soon their offspring were simply “slaves”, not
Indians. Slaves of course
were also subject to relationships with free men.
By the nature of slavery, the slave often didn’t get to exercise any
right of refusal. Not all
relationships between slaves and free men were nonconsensual. Sometimes slaves with whom the owners had relationships were
treated better and had positions as “house slaves” as opposed to field
workers. Regardless of the
individual circumstances, many female slaves were impregnated by their owners,
overseers or others with whom they had no right of refusal. Refusal would result in punishment ranging from whipping to
being sold away from family, in addition to the forced sexual relations anyway.
As a result of the
social situations brought about by slavery, the genealogy of former slaves is
most often unknown. Genealogical
records for slaves, when available at all, are found in the legal transactions
of their owners. Slaves were
valuable property, often the most valuable thing owned by their masters, worth
far more than their land, as evidenced by the 1850 and 1860 census records in
addition to estate inventories. Slave
genealogical records can be found in the deed records, as slaves when sold were
often recorded as deeds, wills and estate settlements and also on the slave
census schedules of 1850 and 1860. Lucky
genealogists will find families grouped together and in estate inventories,
families specifically identified as such. Unfortunately, while it’s relatively
forthright to determine the mother of the children, the father is often much
more difficult. Children were the property of the owner of the mother, and
fathers might live on a different plantation or there might be multiple fathers
due to varying circumstances. Unfortunately,
much of this type of genealogy must be surmised.
It’s inferred, for example, not known, that children found with a woman
are her children unless an estate packet or chancery suit says otherwise.
While most people
whose ancestors were slaves know they are of African descent, what they don’t
realize is that they are also very likely of American Indian descent as well.
Prior to the beginning of large scale importation of African slaves into
American, Indians were routinely enslaved. American Indian
tribes were constantly at war among themselves.
Prior to the settlement of Europeans, they either killed their (primarily
male) captives, incorporated them into their tribe, or enslaved them themselves.
After European
settlement began, Indians quickly discovered a market for their captives and
they began capturing men, women and children and selling their captives into
bondage. This had the unintended
effect of depleting the Indian population as a whole.
Previously, if the captive had been incorporated into the tribe or even
enslaved by the tribe, they had the ability to continue to contribute to the
native population and often had children within the tribe with which they lived.
By selling their captives to Europeans, those not sent to the West Indies
were no longer within the indigenous population, but were effectively now within
what would become the African slave population.
Both American Indian and European heritage would become obscured by the
African heritage. Americans today
whose family has a heritage of slavery aren’t terribly surprised to find
European DNA on their paternal side, and about 30% find this result. Many are surprised to find European DNA on their maternal
side and most are quite surprised to find Native American DNA on either side.
Native Americans
and Africans have been enslaved together on the American soil since at least
1619 in Jamestown when the first slave ships arrived. For the next 243 years, or about 10 generations, the
institution of slavery provided the social environment for undocumented
admixture between European, African and Indian populations.
In fact, in the 1700s in the records of the North Carolina General
Assembly sessions, more than half of the petitions for manumission were indeed
for those noted as mulatto or mixed. Ironically, it isn’t the African heritage
that has been lost in the shuffle, but most often the Indian heritage that is
entire missing from family oral histories.
Bondage itself was considered evidence of African heritage. Indians being
integrated into slavery wasn’t a one way street however.
Many times slaves ran away and were taken in by the various tribes as
members. As tribes became smaller
through disease, warfare, integration with European culture and the effects of
forced relocation, their remnant tribes merged.
The Cherokee, for example, were known to take refugees, including escaped
slaves, and they welcomed other tribal remnants as well to swell their ranks. What does this mean
to the family historian who is trying to prove their genealogy and understand
better just who they are and where they come from?
If your family has
a long-standing oral history of minority heritage, it is probably true. However,
finding the person who carried that heritage is often quite challenging.
Historically, Native people were classified as “non-white” which
severely limited (and sometimes prevented) their ability to function in a
primarily white society. Furthermore, laws
varied and how much non-white heritage constituting “people of color” ranged
from the infamous “one drop” rule to lesser admixture, sometimes much more
liberal, to only the third generation. In
essence, as soon as individuals could become or pass for “white” they did.
It was socially and financially advantageous.
It is not unusual to find a family who moved from one location to
another, often westward, and while they were classified as mulatto in their old
home, they were white in their new location. Often there were
only three or sometimes four classifications available, white, negro or black,
mulatto and Indian. Sometimes
Indian was a good thing to be, because in colonial states, reservation Indians
weren’t taxed. However, this also
means their existence in a particular area often went unrecorded. Often, poor “free people of color” weren’t taxed either
because they lived and worked on someone else’s land and they had nothing of
value. Because of their poverty and
resulting lack of records, they became invisible to the genealogist. Any classification
other than white meant in terms of social and legal status that these people
were lesser citizens. Therefore,
Native American or other heritage that was not visually obvious was hidden and
whispered about, sometimes renamed to much less emotionally and socially charged
monikers, such as Black Dutch, Black Irish and possibly also Portuguese. For genealogists
who are lucky, there are records confirming their genealogy, such as the Dawes
Rolls and other legal documents such as slave owner records.
More often, there are only hints, if even that, such as a census where an
ancestor is listed as mulatto, or some other document that hints at their
heritage. Most often though, the
stories are very vague, and were whispered or hidden for generations.
References may be oral or found in old letters or documents.
Supporting documentation is often missing. Many times, it was
the woman of the couple who was admixed initially, of course leading to admixed
children, but with 50% less admixture than their mixed parent. It was much more common for a male of European stock to
intermarry with Native or admixed women, rather than the other way around. This means to
genetic genealogists today, that they are likely to meet with frustration when
attempting to document minority heritage. Let’s take a look
at DNA testing, the various kinds available, how they can assist us with our
genealogy and what they mean. DNA
Tests To avoid confusion,
this is probably a good place to mention that DNA testing is not accepted by any
tribe for membership. Each tribe
has its own membership criteria and to my knowledge, none accept DNA as either
proof or disproof. Tribes typically
require a percent of “blood quantum”, such as 1/4th or 1/8th
and in addition they generally require that you be of proven descent from an
individual about whom there is no question of their tribal Native heritage.
This is most often accomplished by the inclusion of the family in
question on specific tribal rolls, plus proven descent from that family, and
that the applicant is not currently less than a specific percentage Native
American. Conceptually, this
means that you could very well be mostly Native American, with 7 of your 8
direct great-grandparents being 100% Native American, but your father’s direct
paternal line being European. With
proven genealogy to the tribes specifications and being 7/8th Native
American, there is no question that you would be accepted on the tribal rolls.
However, a Y-line DNA test would reveal the European haplogroup of your
father’s paternal line is not of Native heritage.
Given the above
example, you can never interpret non-Native haplogroup results of any one line
to answer the much broader questions of, “do I have Native heritage”, “how
much” and “where”. What you
can do at that point is to continue to test other lines in order to discover the
identity of your Native American ancestor.
You will need to create a DNA pedigree chart.
But first, let’s take a look at the different kinds of DNA testing and
what they can tell you about your heritage. There are 3
different types of DNA tests that can be used to either confirm or hint at
Native ancestry; Y-line, mitochondrial DNA and autosomal.
There are two types of autosomal testing, that based on the forensic
CODIS markers and that based on biogeographical ancestry markers.
Let’s take a look at these different kinds of tests and what they can
to help us identify our Native ancestors. Y-Line
– Paternal Line Testing Y-line DNA tracks
the male’s paternal line through the Y chromosome that is passed from father
to son. This DNA also follows the
last name of the father, so projects tracking these families are called surname
projects. Comparatively speaking,
these are easy to manage because a male carrying the last name of interest is
obvious. Y-line DNA can tell
you whether or not you descend from a common male genealogically when compared
to another testing participant. It
can also tell you by identifying your deep ancestral clan whether or not you
descend from early Native Americans who were here before contact with Europeans.
For that matter, it can also tell you if you descend from those of
African, European or Asian ancestry. Scientists know
today that there are only two primary haplogroups indicating deep ancestry that
are found among Native American males who were here prior to contact with
Indo-Europeans, and those haplogroups are C and Q.
It is not accurate to say that all C and Q individuals exist only in the
American Native population, but the American Native population is part of the
larger group worldwide that comprises C and Q.
Subgroups of haplogroups C and Q which we find only among the American
Indians are C3b (also known as C-P39) and Q1a3a (also known as Q-M3).
We find no C-P39 or Q-M3 in European or African populations, although we
do learn more every single day in this infant science. This sometimes
becomes confusing, because the single most common male haplogroup among current
Cherokee tribal members who have tested is R1b. How can this be, you ask?
Clearly, one of three possibilities exists:
Given this
situation, I want to be very sure that people do understand that DNA results and
tribal membership are not related. Because of the
unique haplogroups for Native Americans who preceded European contact, Y-line is
the only way to positively confirm that a specific line is or is not of Native
American descent. This obviously
applies to all of the individuals in the pedigree chart who directly descend
from the oldest known ancestor in this paternal line.
Y-line testing does
not indicate anything about the contributions of the other ancestors in this
family tree. Mitochondrial
DNA Mitochondrial DNA
tracks the participant’s maternal line. Mitochondrial
DNA is passed from the mother to all of her children, but only the females pass
it on. So both men and women can
test themselves to reflect the mitochondrial (mtDNA) DNA of their mother, but
following it up the ancestral tree, the path of ascent is only through the
mothers. Your mtDNA is the mtDNA of
your mother, her mother, her mother, etc. on up the tree following only the
maternal line. MtDNA testing is
not as popular as Y-line testing because it’s more difficult to use
genealogically as last names change every generation.
When you look at your matches, you have no idea whatsoever if you might
be related to these people in a genealogically relevant time frame by looking at
their last names. Those who have
put forth the effort to collaboratively work on their mtDNA matches, assuming a
high resolution match and a shared geographical history as well, have been
pleasantly surprised by what they’ve found. A haplogroup
assigning deep ancestry is also provided through mitochondrial testing, so like
the Y-line, depending on the haplogroup assigned, you will know if your
ancestors were here before the age of European contact.
Female haplogroups that indicate Native heritage include A, B, C, D and
X, although, like Y-line, these major haplogroups are also found in Eurasian
populations while typically subgroups are found in the Americas.
The certificate
below shows a typical certificate from the mtDNA test.
Some additional information, along with matches, is available on the
participant’s personal web page if they are Family Tree DNA clients.
Clients of other testing companies receive varying amounts of information
ranging from none to a printed report. The pedigree fan
chart below, courtesy of Family Tree DNA, shows the inheritance pattern for both
Y-line and mtDNA. Notice that of the
16 individuals shown as the great-great-grandparents of the siblings, the Y-line
and mtDNA positively identify the deep ancestry of only two of the 16 branches,
leaving 14 unidentified. It is
certainly possible that their Native heritage descended through their father’s
family pedigree, but was not reflected in the Y-line of that line.
The Native American individual could have been any of the people on the
father’s half of the tree other than the surname branch that was tested, or
perhaps even someone further up the tree not shown here. Both Y-line and
mtDNA can provide this level of deep ancestral accuracy because both are passed
from parent to child without being admixed with any DNA from the other parent,
allowing us today to determine exactly what the DNA of those paternal and
maternal ancestors looked like, with the exception of an occasional mutation.
Because of the
accuracy of both Y-line and mtDNA testing, I strongly encourage people to
attempt to complete their Personal DNA Pedigree Chart (see article by Roberta
titled “Creating Your Personal DNA Pedigree Chart”) by finding appropriate
testing candidates, representatives of the other genealogical lines found on
their tree. It may indeed require
some work, especially to identify individuals descended through maternal lines
with last names changing each generation, but it is the only way to accurately
reconstruct your genetic heritage. Y-line and
mitochondrial DNA testing is the only way to positively identify which
individual line or lines were of Native (or African, European or Asian)
heritage, although other types of tests, called autosomal and/or biogeographical
tests can be done to indicate the existence or absence of Native American (or
other) heritage, no other tests can pinpoint where the Native heritage entered
the family tree and which ancestors were of Native heritage. Autosomal
DNA Testing Unlike Y-line and
mtDNA testing where the DNA of the father or mother is passed to the offspring
unmixed with that of the other parent, autosomal testing tests portions of the
DNA of an individual that they receive from both parents.
As the field of genetic genealogy has moved forward, research has begun
to indicate that certain markers are found in higher or lower amounts in
different ethnic populations. For example, if
someone has the Duffy Null allele, or genetic marker, we know they positively
have African admixture. We don’t
know how much African admixture, or from which line, or when that individual
with African admixture entered their family tree, but we know for sure they
existed. Attempting to
determine the population frequency of varying markers and what that means
relative to other populations is the key to this analysis.
Few markers are simply present or absent in populations, but are found in
varying frequencies. Some
populations are widely studied in the research literature, and others are
virtually untouched. The process of
compiling this information in a meaningful manner so that it can be analyzed is
a formidable task, as the information is often found in nearly inaccessible
academic and forensic research publications.
It’s difficult to determine sometimes if the DNA analysis of 29
individuals in a small village in northern Italy is, for example, representative
of that village as a whole, of northern Italy, or more broadly for all of Italy
as a whole. Is it representative of
Italy today or Italy historically? These
and other similar questions have to be answered fully before the data from
autosomal testing can be useful and reliable. If the DNA tests
being performed aren’t mtDNA or Y-line, then they are autosomal tests, meaning
they are performed on the balance of the DNA contributed by both parents to an
individual. Before we discuss
the varying kinds of autosomal tests and what they mean, let’s take a look at
the inheritance process and how it really works. Inheritance Everyone knows that
you inherit half of your DNA from your mother and half from your father.
While this is technically true, you don’t receive 25% of your DNA from
each grandparent. While each child
does on the average receive 25% from each grandparent, the actual inheritance
pattern varies much more than that and each sibling may receive far more, or
less, than 25% of their markers from any grandparent.
We don’t
understand today how inheritance traits are selected to be passed to children.
Each parent receives 50% from each of his parents, but how this is
combined and reduced to the “half” that is passed to each child is unknown.
Every individual has 2 chromosomes in each pair, one from each parent,
but their DNA recombines to create one “new” chromosome to be passed to each
of their children. Some “groups”
of genetic material are inherited together, and you may wind up with more or
less genetic material from one of your grandparents.
In time, certain genetic “traits” will be lost in some descendants,
while not in others. Therefore, you
can’t figure actual inheritance percentages by using the 50% rule.
This means that if your father was 50% Native American, you are not
necessarily 25%, genetically speaking. You
may receive 10% of his Native genes and your sibling may receive 40%. Let’s use the
Duffy Null allele we mentioned earlier as an example.
This marker could have entered your DNA pedigree chart with a grandmother
who carried the allele but had no obvious visible African ancestral traits, or
from your father who might have been visibly African in ethnicity.
The Duffy Null allele, which is just one marker, could have been passed
in the inheritance of DNA for many generations, far after any visible physical
African traits had disappeared, or it could be one of many African traits passed
from parent to child. It is also
possible that an individual who is admixed, whether they know it or not, and
physically appears to be African (or of African descent), has lost the Duffy
Null allele someplace along the line in recombination and transmission. The relevance of
the Duffy Null allele is determined by the number of other “African” markers
that appear in high quantity. If
there are few other African markers, then your African ancestry was likely
further back in time. If there are
many, then your African ancestry was likely more recent.
These statistical calculations are how the importance of autosomal
markers are determined and how percentages or estimates of ethnicity are
calculated. Any one allele or
marker can be lost permanently in any generation.
Each child receives one gene from each parent. In the example below, let’s say that the mother carried
genetic markers A and B, and the father C and D, and D is the Duffy Null allele. You can see that
half the children received the D marker, but each inheritance event was a random
recombination of the markers. It is
also possible that none of the children would receive the D marker, or all of
them would receive it. Statistically
speaking, half will receive the marker, but statistics and individual
inheritance are two different things. Random
recombination is the reason why siblings who take autosomal tests sometimes show
significantly different results. You can also see
how a marker that is very old ancestrally, meaning introduced many many
generations ago, could be absent in one entire descendant line and present in
another line. From the above
examples, we see that we have two variables that we need to deal with when
attempting to use autosomal DNA for genealogy.
First, we need to
take into consideration inheritance patterns which we can’t determine
retrospectively without testing several descendant lines.
So, in essence, we can only deal with, and test, what we personally carry
today as our genetic inheritance. The second variable
is determining population frequency for a particular marker and understanding
its significance to us through comparative population genetics. This is why
autosomal testing can give us important hints, but is often considered
“unreliable”. The results
are highly subjective today, but increase in accuracy as more research is
completed, compiled, published and analyzed. Types
of Autosomal Tests There are two types
of autosomal tests used today for genetic genealogy. One type of test uses the Codis forensic markers and the
second type, biogeographical tests, use a much broader spectrum of marker
results called AIMs (Ancestry Informative Markers).
Let’s look at both types of testing and the information they provide
separately. Codis
markers are a standardized set of autosomal markers used for paternity and
siblingship testing. Additionally,
they are used by police departments and forensics labs. The markers employed in these tests are selected specifically
to differentiate between people in order to identify them individually,
not to find common markers to place them in ethnic groups.
The results from
these tests are only numbers, and the recipient is often left to their own
devices as to how to interpret the results.
These tests are available from numerous sources.
I prefer to interpret these results in conjunction with Y-line and
mitochondrial DNA test results for as much of the genetic pedigree chart as can
be provided in order to obtain a more complete genetic picture. Below is an example
of what Codis test results look like. They
are very similar from any lab.
Analysis
of Codis Markers Unless you’re
using the Codis marker results to determine siblingship or some other personal
reason, these numbers are fairly useless genealogically. It’s the analysis of these markers that matters. There are different
avenues to analyze Codis results. None
are “right” or “wrong”. DNAexplain
(www.dnaexplain.com)
provides analysis of these tests, along with broader more comprehensive analysis
of genetic genealogy and what all of these tests together mean about you.
We use a
combination of resources, both public and private, including Omnipop and other
European and Canadian autosomal forensic data bases.
Tribes (www.dnatribes.com)
has been compiling population data on these genetic markers for some years now
and will compare your autosomal results with their data base.
Take a look at their samples tab. Ironically, the
results may vary significantly between these resources.
There is no “right” or “wrong” answer at this point. I encourage
everyone to simply view these results as “data”, hints to puzzle pieces.
As the data bases improve and we better understand population migration
and movement, the clarity of the results will improve too. Tribes early
population tables did not include data from the British Isles, so their results
were highly skewed towards other world populations.
Omnipop today relies on self-reported ethnicity and does not include
normalized data (or a normalizing factor) for varying populations.
Because Tribes is a private company, we don’t know much about their
population data, whether it’s widely representative of the world population
distribution and whether it has been normalized or not.
To learn the most
about your autosomal test results, you can take a dual approach, having them
analyzed by Tribes as well as by DNAexplain using the other autosomal codis
reference tools. We’ll be glad to
help you through this process and provide a summary analysis of both. Testing for the
Codis markers is available though Family Tree DNA and also through DNATribes.
If you are purchasing this test from any other lab, be sure before you
purchase the test that it includes the various markers needed for Omnipop and
the DNATribes analysis. DNAPrint
Genomics Biogeographical
ancestry testing was previously available from DNA Print Genomics (www.dnaprint.com),
however, they have now filed for bankruptcy and are out of business.
However, biogeographical testing is the second type of autosomal testing
and many people in the genealogy marketspace have taken this test.
DNAPrint evaluated all of your genetic contributions for specific,
proprietary markers that indicate geographical heritage, not just the Y-line or
mtDNA. Results were returned as percentages of Indo-European, Asian, African and
Native American. They did not use
the Codis markers, but use, depending on your test selected, between 500 and
1349 biogeographical markers they had discovered to be relevant to ethnicity.
This test itself
was only available from only one source, DNAPrint, although the test was resold
by several other companies under varying names.
Results from this test were returned as percentages of ethnic heritage as
shown below. Results were
reported within confidence bands, which indicate a range of percentages that
might actually be accurate. This is
shown above by the bands surrounding the red dot which shows the “most
likely” result. The margin of
error is often as high as 15%. Typically,
there is no dispute over the majority ancestral type.
However, minority types are apparently much more difficult to discern.
Because of the wide and sometimes surprising range of results, this test
was often considered unreliable, but the degree of unreliability sometimes was
determined by how pleased the tester was with their results. It is unfortunate
that DNAPrint is now defunct. While
the test did indeed need refinement, without continuing research, there will
never be a test to offer this type of information to consumers who seek answers
otherwise unavailable to them. Having said that,
let’s talk about the concept of statistical noise, which in this case (DNAPrint)
according to their documentation was as high as 15%.
All testing that deals with statistics, which means by virtue of the
nature of the beast, all population based autosomal tests today, deal with
“statistical noise” at some level. Statistical
Noise Statistical noise
is easy to understand. It’s a scientific word that means the percentage of
“slop” in the calculations based on what they don’t know.
When scientists perform calculations based on populations, they have to
sample an incredibly large number of individuals for the law of averages to work
in their favor. For example,
sampling 50 individuals from inner city Detroit may not be reflective of the
entire state of Michigan’s population or even of the population of Detroit
itself, depending on which neighborhood you’ve visited to collect samples.
However, many companies base their entire estimates of heritage on 50 or
fewer samples from particular countries. A much more
reasonable and accurate approach would be to take samples from a percentage of
people, based on population, throughout Michigan.
That approach is difficult and expensive. To attempt to compensate for the issues inherent in the
smaller sample approach, there are various calculations that are used on the
results to “normalize” them. The
resultant “unknown” or “margin of error” is considered statistical
noise. It’s much like the
political surveys taken that are always qualified by “+ or – a 5% margin of
error”. So what does this
mean to genealogists trying to understand their results? What this means is
that any number that you received could in actuality be 15% higher or lower than
stated. For majority ancestry, this
is not a problem, but for minority ancestry, which is the information most
people are seeking, it represents a huge problem.
Looking at the East-Asian and Native American results above, that means
that they could actually be zero to 22% (East-Asian) or 17% (Native American).
Now let’s connect
this to genealogy. If we use the
figure of 50% inheritance in each generation, knowing that it’s imperfect
because we don’t receive 25% of our genes from each grandparent, we know the
following about our individual inheritance. Parents – 50%
from each one Grandparents –
25% from each one Great-grandparents
– 12.5% from each one Great-great-grandparents
– 6.25% from each one For most of us,
average age of 50 (genealogists don’t tend to start young), and with an
average generation length of 30 years, this equates to the following
information: Us –born about
1960 Parents – born
about 1930 Grand-parents –
born about 1900 (we probably knew them) Great-grandparents
– born about 1870 (we probably didn’t know them, but our grandparents and
parents told us about them) Great-grandparents
– born about 1840 (we definitely didn’t know them, but we probably knew who
they were genealogically as our grandparents knew them) For most people, if
our great-grandparents had been Asian, African or Native American, born about
1870, we would have known it. In
this generation, we are within the statistical noise 15% ration as we only
inherit (on the average) 12.5% from each of these individuals.
If they were “full blooded” anything, it wouldn’t be a secret that
needs to be ferreted out by DNA testing. By 1870, there were
very few American Indian people who were not admixed with European or African
ancestors, although they might have been unaware of that fact if it occurred
several generations previously. Most
of the least admixed individuals were on reservations by 1870 or living in the
west. Indians living in the east
were admixed enough to not have been removed in the 1830s.
By the
great-grandparents generation, we are now at the 6.25% level, well with the
noise range, but within the timeframe where we should receive at least some oral
history. The 1850 census is our
friend here, as we can determine where they lived, if they were on a
reservation, and if they were considered anything other than “white”, such
as black or mulatto, as many admixed American Indians were labeled. Most people who
seek to discover their Native American ancestry are by necessity looking back
before the “Trail of Tears”, often to the tribes that were exterminated by
the colonists before the Revolutionary War.
Remnants of those tribes intermarried with whites and free people of
color as well as joining the tribes still existent, such as the Cherokees and
Creeks who were later removed. Unfortunately, on
the genealogy chart, this takes us back another two generations to ancestors
born in 1810 and in 1780. Respectively,
we carry an average of 3.125% and 1.56% of their DNA. The next generation back, born in 1750 before the
Revolutionary War, we carry less than 1%, on average, of their individual DNA.
It’s no wonder
that the autosomal tests have such a difficult time finding traces of our Native
ancestors. Unfortunately, because
of the way DNA is recombined and transmitted generation to generation, we simply
can’t unlock those secrets to day. What
we can do is to participate in new testing as it comes along and use the various
pieces of information available from each type of test to build our “case”. DNATribes DNATribes has been
a provider of products in the genetic genealogy field for several years.
They use the Codis markers and provide an analysis from their data base
relative to the markers and the populations in which they are found.
They combine this population data into a trend and provide you with a
report based on their findings as to which populations you are most likely to
match. Considerations relevant to
these results are mentioned above in the Statistical Noise section. DNATribes products
match you against the various world populations and report your most likely
matches. An example is shown below. Their reports begin
at about $99 and they can also provide CODIS Marker testing if you have not been
tested elsewhere. D9S919
Autosomal Allele From the halls of
academia a paper was published a couple of years ago that indicated that about
30% of the Native Americans tested carry a certain value for this particular
autosomal marker. These values are
not known to occur in other populations. This
makes this particular marker extremely useful in determining whether an
individual carries Native American admixture. A value of 9-10
confirms Native admixture, but a value of anything else does NOT disprove Native
admixture. This test is only
available at Family Tree DNA for existing customers under Advanced Orders,
Autosomal Markers, Panel 3, for $15 plus a transfer fee of about $10 if your DNA
is not already in the Houston lab for advanced testing. 23andMe
Ancestry Testing A recent entry into
the field of consumer genetic testing is the firm 23andMe, owned by the wife of
Google’s founder. They are focused on testing that is not just for ancestry,
but includes a significant amount of medical information.
This is not equivalent to genetic genealogy testing, as there is no
matching with others by surname, projects and etc. What this does
offer is a much wider range of tests on 580,000 locations on your genome.
Today, you can’t separate out the medical and ancestry testing, so if
you don’t want the medical, you’re getting it anyway.
Take a look at their website at www.23andme.com
for details. The price is about $400. In addition to your
Y-Line haplogroup (for males) and your mtDNA haplogroup, they also provide
consumers with an estimation of their percentage of ancestry, although they only
include European, Asian and African, and their sample size is small, in many
cases about 50 individuals per population, which I feel is much too small to be
reliable. They recently
introduced a feature called Native Ancestry Finder that evaluates your mtDNA and
Y-line haplogroups, plus your percent of Asian heritage and tells you whether or
not you’re likely to have Native Ancestry.
In my case, it says I’m unlikely, but that it’s possible beyond 5
generations. Given my finding at
their lab of 99% European and less than 1% Asian, they’re not incorrect, but
their evaluation adds nothing that I didn’t already know from other sources.
Their results are the lowest for Native/Asian/African admixture of all of
the testing companies. Having said that,
here is an example of the ancestry results.
DeCode
Genetics Another entrant
into the same arena, about the same time, is DeCode Genetics from Iceland with
their deCodeMe product offering. DeCode
Genetics is a well known biomedical company for their research into heart
disease and related genetics. Unfortunately,
with the Icelandic government’s collapse following the banking industry
crisis, deCode Genetics is now in bankruptcy, but is still functioning.
You can see their products at www.decodeme.com. The ancestry
portion of their offering is only available if you purchase the entire testing
package, which costs $985. Their
package is similar to 23andMe in that they offer primarily medical testing. Here are examples
of their ancestry results. Of
interest, they display the entire X chromosome which 23andMe does not.
In my case, this is a critical piece of information as my “Asian”
ancestry is pronounced on the X chromosome.
The X chromosome has a particular inheritance pattern and this limits the
possibility of who, on my pedigree chart, contributed that “Asian” DNA
substantially.
Summary There are only two
tests that can provide you with solid evidence of the source of your Native
American or other ethnic ancestry. Those
are Y-line and mitochondrial DNA tests. It’s
important to try to fill in the blanks in your family tree pedigree chart by
testing relatives who carry the Y-line and/or mtDNA of the lines of your tree
that you cannot personally be tested for. It’s
also important to test at Family Tree DNA, because they provide SNP testing for
accurate haplotype identification for both mtDNA (free) and Y-line (if it cannot
be accurately predicted based on identical matches to SNP tested individuals).
Additionally they provide surname, geographic and haplogroup projects and
customer support (by a qualified person) by phone or e-mail if needed. In addition, two
types of autosomal testing can provide useful clues as to the percentage of your
ethnic heritage and the geographical source.
DNAPrint provided percentages of ethnicity of the 4 major world groups,
European, Asian, African and Native American, but they are no longer in
business. DeCodeMe and 23andMe
provide something slightly similar in their predictions, but neither test for
Native ancestry. People of European
descent must allow Asian heritage to infer Native Ancestry. Codis marker
testing is another type of autosomal test used to determine the Codis marker
values which in turn can be used to map those marker values against known
population groups. OmniPop is a
tool that is used to view population matches, although issues persist relative
to the identification of individuals and populations used by OmniPop and other
tests of this type. DNATribes
provides a population matching service using their internal database. D9S919, an
autosomal allele, can be tested through Family Tree DNA who also provides Codis
marker testing. The values of 9-10
can confirm Native ancestry, but other values do not eliminate the possibility. DNAexplain provides
autosomal analysis services for Omnipop and other public databases in addition
to analysis services for Y-line and mtDNA test results. All genetic
genealogy results need to be accompanied by genealogical research to unravel the
historical context for the lives and trials of our ancestors.
DNA testing may well answer the question what and who, but the why is
typically revealed only by studying the history of the times in which they
lived. Roberta
Estes Copyright
2007-2009, Roberta Estes, all rights reserved
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