Every Black History Month, many Americans and Canadians of African descent are confronted with one simple question – why do we need a Black History Month? After all, there’s no month dedicated to white history or gay history. The black history tradition dates back to 1926 and was founded by American historian Carter G Woodson, who sought to preserve and propagate knowledge of the artifacts and publications about the contributions of African-Americans to American life. The holiday was originally called “Negro History Week” and later expanded to a month-long celebration.
Of course this all took place before the rise of mass media, the internet and, most importantly, the legal rights that allow blacks in the United States to control their own destiny. Now in the digital age, discovering black history is as easy as visiting Wikipedia or scouring for an old copy of Encyclopedia Africana. So, why are so many black people still deeply attached to a concentrated celebration of widely-available information?
Part of the answer may be that assorted factoids about George Washington Carver and Harriet Tubman are the most intimate history many blacks have – due in part to slavery and the destructive breeding practices learned from that era. History within individual families can be hard to follow, with available information starting after the slave ship landed on American soil. The very label “African-American” implies a lack of knowledge about actual ethnic identity – a Somali has a considerably different culture and history than a member of the Ashanti tribe. Comparatively, the term European-American is rare except when in use by white nationalists. The majority of white Americans will refer to their heritage by nation – Irish-American, German-American, etc – and celebrate the specific contributions of those ethnic groups to American culture.
Fortunately, African-Americans no longer need to rely entirely on historical records to determine their ancestry. Specifically, DNA Ancestry testing has become tremendously popular over the past few years by promising to discover long-lost African history through genetically linking users to pre-defined samples of African ethnic groups. Some services, like Ancestry.com and DNA Consultants, offer comprehensive testing while other services like African Ancestry concentrate specifically on African heritage.
But what benefit can be gained from such services and how believable are the results? I’ve spent the better part of a year overseeing tests for myself and others as well as doing some research into the benefits and limitations of DNA testing. A summary of DNA Testing as well as my own experience will be spread over three blog posts. Readers are encouraged to submit their own experiences with DNA testing.
What can a DNA Test Tell you?
Present DNA ancestry testing is based on scientific findings that all present-day human beings can be traced back approximately 150,000 years to common ancestors in East Africa. Various waves of early humans migrated from Africa to different parts of the globe and their DNA mutated in tiny increments. These natural mutations, known as single-nucleotide polymorphisms (SNP’s for short) occurred randomly every few thousand years and were passed down from generation to generation. While these mutations are complex and there can be many different sequences (also known as Haplotypes), mutations are generally quite similar for early humans that migrated to the same part of the world around the same. Haplotypes are thus clustered into haplogroups, which are understood to have a common ancestor. There are separate male (Y-Chromosome) and female (X-Chromosome) haplogroups which are distributed geographically.
Three types of DNA tests can be used to determine ancestry:
mtDNA – Short for mitochondrial DNA, mtDNA is carried by both males and females. However, mtDNA is passed exclusively from mother to child, meaning an mtDNA test can only determine your mother’s contribution to your genetic makeup. Since this relationship is true all the way up your family line, mtDNA ancestry tests can determine the origin of your mother’s mother’s … mother. Because mtDNA is only inherited from mothers, it does not change (or mutate) significantly over time (due to the slow-changing nature of SNP’s). This slow rate of mutation allows scientists to determine the long term origin (also known as “Deep Ancestry”) of your maternal line.
yDNA – Y-Chromosomes works in a similar manner to mtDNA, except that they are only passed from father to son. Thus, only males have yDNA tests. Females wishing to discover their deep paternal lineage must have a paternal male relative take the test (e.g. father, brother).
(side note: human females obtain X-Chromosomes from both mother and father; thus, “X Chromosome” cannot be used interchangeably with mtDNA in this instance)
Autosomal – Every human has 22 pairs of autosomal chromosomes. There are equal copies of the autosomal chromosomes in males and females, allowing genetic identification based on the heritage of both parents. However, autosomal DNA is not “deep”, as the 22 pairs are inherited randomly from parents (for a given pair, one chromosome comes from each parent; each parent can pass 1 of 2 chromosomes, meaning 4 possible configurations per pair). No two people -except for identical twins- have the exact same autosomal DNA, which contrasts with the direct inheritance of yDNA and mtDNA.
What can’t a DNA Test tell you?
So with all of this technology, it should be easy to figure out where you originally set up shop before the transatlantic trip, right? Not quite. Apart from the fact that an overwhelming percentage blacks in the western hemisphere are of mixed heritage, the current testing methods have noteworthy limitations
- yDNA and mtDNA tests are single-line. This means that they measure straight inheritance via mother or father only. Thus, one cannot use mtDNA to test whether a mother’s father is part-native because the mother’s mtDNA comes exclusively from her mother. Similarly, yDNA only provides information on a line of fathers. Thus, even combining mtDNA and yDNA tests will not allow a person to determine their entire ancestry.
- Autosomal DNA can only reliably measure back to the grandparent generation. Typically, autosomal DNA used in paternity testing, crime scene investigation and other situations where either exact identity or close family relationship needs to be established.
- Autosomal DNA cannot determine what percentage of each ethnic group is in a person’s total makeup
Ergo, it may not be possible to tell whether you are a direct decedent of the Zulus unless either your mother’s mother’s … mother or father’s father’s … father happens to belong to that ethnic group. If you are so lucky it will still not possible to determine just how “Zulu” you are.
Discovering your Ancestry through Genebase
There are many different websites and offline services offering DNA testing as a way to discover heritage. Being Canadian and somewhat concerned about how foreign governments might use a DNA sample, I chose the Vancouver-based Genebase (note: many Americans also use this service).
Genebase offers mtDNA and yDNA test kits of varying comprehensiveness (and prices) for ancestral discovery. The initial tests are STR (short tandem repeat) tests that can be used to predict haplogroups. Additional SNP tests can be ordered to confirm haplogroup, and most recently Genebase has added subclade tests for further confirmations.
For example, a male users interested in his paternal ancestry could order the Advanced Paternal Ancestry Package (Y-DNA 44 Marker Test). After the test predicts that he belongs to the J haplogroup, he could confirm this by upgrading with a Y-DNA DNA haplogroup Backbone SNP Test. If the client wants more detail he could choose to order the Y-DNA J Subclade SNP Test and use the results to determine the probable region form which his earliest haplogroup member originated.
Apart from haplogroup identification, Genebase offers two other useful ancestry tools for incoming DNA samples -
DNA Reunion – yDNA and mtDNA STR markers can be compared to all the other users in the DNA database. The software ranks user matches according to number of overlapping markets to be compared between two users and the genetic distance (calculated by number of markers that have different values). For the example above, the user might upgrade from a 44 marker test to a 67 marker test, since having a larger pool of markers to test will improve the probability of finding matches. Using the search preferences, he can direct DNA Reunion to return a list of users who have a maximum genetic distance of 1 (ie only 1 marker different) out of a minimum 18 overlapping markers. The results might show that the majority of users matching this criteria reside in Egypt, suggesting (though not proving) that user’s deep ancestral roots may lie in that region.
Indigenous DNA – Similar to DNA Reunion, except DNA samples are compared to indigenous (and some non-indigenous) groups from around the world. The software makes STR comparisons over several different journals using a selectable number of marker matches. Again, the results do not strictly prove ancestry but are an excellent aid for determining probability.
Autosomal test kits are also available and are used in DNA Reunion – however Genebase only uses autosomal DNA to match near family relations to others users in the database. This contrasts to many other ancestry services which use autosomal DNA to predic ethnic identity. Still, autosomal testing could be used for cheap, legal paternal testing.
At one time DNA kits used to be available in Best Buy but these days it seems the only way to get a kit is to order directly from the Genebase website. The kit is mailed to the user’s home with a return envelope, small swab brushes and full instructions on how to collect a buccal swab. Once the sample is returned, processing takes place over the next few weeks and the results are uploaded to a website. The user can then view the results and start using the tools described above.
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