We all wonder where we really come from, and especially on Heritage Day, when in some workplaces, we’re asked to don our “national costume”. My heritage is pretty mixed, so a Union Jack with some Dutch orange, a Greek bolero and a four-leaf clover for luck would do it, albeit a little peculiar.
The search for identity has driven some of us to genetic ancestry testing. But can it really tell you who you are? It definitely cannot, says Prof Himla Soodyall, executive officer of the Academy of Science of SA (ASSAf), and a research professor in human genetics at the University of the Witwatersrand. And nor can it detect your race.
Soodyall is one of our foremost genetic scholars, and her research into the peoples of Sub-Saharan Africa has identified some of the oldest DNA found in living people today, adding weight to our proud claim that modern humans evolved in Southern Africa.
Soodyall initiated the ancestry testing service that the National Health Laboratory Service (NHLS) used to run at the Wits Origins Centre, and presented it with Dr Rajeshree Mahabeer, who is now also at ASSAf. The programme’s information booklet, “Genetic Ancestry Testing”, which was handed out to each candidate who came to the presentation and volunteered to have their DNA analysed, states: “Identity is a complex issue and no genetic test can tell you who you are. Identity does not equal genetic ancestry. Therefore an mtDNA test cannot be used to tell you who you are.”
For a humanities graduate who has always studiously avoided the scientific, I found the booklet almost impenetrable, but several rereads did shed light. I do know, however, that DNA is the blueprint for all life, and the map to our genetic information. Soodyall said the ancestry-testing service at the Origins Centre was a valuable resource for the public to learn more about science. But it was decided it was not a core NHLS function and was halted in 2019.
The test can be done at home, with the help of a kit that you can order online. The internet sites offering genetic ancestry testing, however, may be claiming to offer more than they deliver. “Quick, easy and affordable DNA tests. Start unearthing your origins and learn more about your ancestors with […] ancestry DNA testing services,” says one.
The important thing about mtDNA is it is shared by many generations of the same mother-line.
The reality is more complex, and I was interested in the process that goes into tracing my ancestors of up to 100,000 years ago. It appears the vital link is mtDNA, because this is what leaves the traces.
Mitochondria are structures within cells that convert the energy from food into a form that cells can says, says the handbook. They have a small amount of their own DNA, known as mitochondrial DNA (mtDNA).
“The important thing about mtDNA is it is shared by many generations of the same mother-line.
Some other FAQs are: Why is mtDNA used for ancestry testing? “Shortly after the process of fertilisation, the sperms' mitochondria die away, and the embryo is only left with mitochondria provided by the mother’s egg. Thus, we share the same mtDNA as our mothers, brothers and sisters, but not our fathers. MtDNA is also passed down nearly unchanged from generation to generation. So we share the same mtDNA pattern as our mother, our maternal grandmother, our maternal great-grandmother and so on. In fact the exact same mtDNA code will track our direct genetic line back until the point at which a natural mutation in the mtDNA code occurred — on average about every 20,000 years,” they say.
Common ancestor
“Ultimately we all trace our mtDNA back to one woman who lived in Africa around 150,000 years ago, who is commonly referred to as ‘Mitochondrial Eve’.” The correct terminology today is “most recent common ancestor” (MRCA) rather than a reference to a biblical Eve.
Homo sapiens first began leaving Africa about 90,000 years ago, spreading across Europe and Asia and finally towards Australia and South America. “Since that time, descendants of this hypothetical MRCA have gradually populated the entire globe, with the original founder group spreading geographically and branching genetically in the course of the millennia, leaving genetic footprints.”
These footprints, say the authors, are mutations in the mtDNA, which are passed exclusively through the mother-line. “By studying global patterns of variation found in the mtDNA of living people we now have a better idea of which mutations have contributed in generating the branching pattern of the mtDNA tree. Thus by studying your mtDNA it is possible for us to identify your leaf (mtDNA pattern) on the mtDNA tree.”
How are the results interpreted? “After we obtain your mtDNA control region … sequence in the laboratory, we compare your sequence profile for this region to a published sequence referred to as the Cambridge Reference Sequence… We use about 800 base pairs of sequence from two specific regions within the control region where mutations are more concentrated…
“We then list the mutations and the positions at which they occur. Some of the changes/mutations characterise the branching pattern of the mtDNA tree. We call these informative sites.”
The sequences are organised into haplogroups, or the “genetic population group of people who share a common ancestor on either their paternal or maternal line”, according to the International Society of Genetic Genealogy. “Haplogroups can reveal deep ancestral origins dating back thousands of years, or with recent full-sequence Y-DNA testing may be relevant to the last few generations.”
Soodyall and Mahabeer add that: “About 60,000 years ago a founder group moved out of Africa and their descendants, through the natural process of mutation, formed the haplogroups M and N. These groups in turn gained a foothold during the Ice Age in Asia, Australia and parts of Europe and evolved their own specific types. So, for example, Europe is populated by the haplogroups H, I, J, K, T, U, V, W and X; Asia by A, B, C, D, E, F, G, M, and Y; the Americas by an Asian branch with A, B, C, D and X ; Papua New Guinea by P and Q; and Australia by further M and N types.”
L lineages are more common in Africa, but some people who are white from Europe can also have mtDNA L lineages if their maternal ancestry stemmed from Africa at some point in their history, they say. “In SA, about 8-10% of people who self identify as white have inherited mtDNA lineages from indigenous African ancestors.”
This means the tests will reveal a wide geographic area rather than a precise point on the map, although, tantalisingly, the genetic ancestry testing site livingdna.com says: “Particular haplogroups are associated with well-known ancestral groups such as the Vikings, Aboriginal Australians, and the Celts.”
Roots?
The Facebook page of Mediclinic, which offers a “precise ancestry test”, says: “Your parents may have told you that you have a ‘Viking temperament’, but do you really have Northern European roots?”
It’s unlikely you’ll find anything as precise as a Viking, Egyptian or Pedi ancestor. Still, if you are willing to gamble about R2,000, you can try out one of the online services. Mediclinic operates through Takealot, which will send you your sample kit, with a consent form with privacy guaranteed. You then take a DNA swab and send it all back.
The Mediclinic report undertakes to “provide information about the ancestral and/or geographical origins of the ancestral populations as well as a short information blurb about that particular geographical region. When it comes to the mitochondrial (and in the case of men, Y chromosome) analyses, we are able to provide an ancestral/geographical origin as well as a date. This date depends on what mtDNA and/or Y chromosome haplogroup comes up, but it can reach back > 100,000 years.”
Other companies that offer the service in SA are International Biosciences, DAnalysis and EasyDNA.
Mediclinic’s site offers handy sample reports for “John Doe” and “Jane Doe”. These sketch an imaginary client’s genetic contribution to particular regions in the various continents, such as Central Europe or East Africa, as well as whether there is a presence of groups such as Khoe San, Ashkenazi Jew, and Bantu speaking. But more than that is out of reach.
Someone who shed light on the area of human mitochondrial genetics was Bryan Sykes, an Oxford University human genetics professor who died in 2020. In his half-nonfiction book, The Seven Daughters of Eve, Sykes revealed how the identification of the strand of DNA that passes unbroken through the maternal line has allowed scientists to trace the genetic makeup of most native Europeans to prehistoric times, and finally to seven primeval women.
He named each woman after the haplogroup in question: Ursula for Haplogroup U, Xenia for X, Helena for H, Velda for V, Tara for T, Katrine for K, and Jasmine for J.
In his book, Blood of the Isles, Sykes describes how he accessed the DNA by drilling into the 12,000-year old tooth of a man found in Cheddar Gorge in Somerset in 1986. The book was the first to be written about the genetic history of Britain and Ireland using DNA as its main source of information.
Sykes’s work was considered groundbreaking because the mitochondrial record shows that most modern Europeans may be indigenous to the continent, having settled that area as hunter-gatherers area long before the agricultural revolution, about 10,000 BC, and as far back as 45,000 years ago.
Having discovered through genealogical research that my great-grandfather came from the Greek island of Skyros, I am curious to know whether I am related, however distantly, to Sykes’s Katrine. Her stamping ground was reportedly Southern Europe, and perhaps even Greece, which I quite like having always fancied myself as a Spartan warrior or a Grecian priestess.
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