How far back have you got with your family tree? 150 years…? 300 years…?
How about two hundred thousand years…?!
One of my goals for 2019 was to develop my understanding of DNA for genealogy. I became interested in this in 2013 but hadn’t made much progress. Although the main type of DNA testing used for genealogy is autosomal, my introduction was through learning about two other tests: mitochondrial and Y-chromosome. In future posts I’ll say more about my experience so far of using autosomal testing alongside traditional documentary research. But today I want to start by going back to the beginning… both in terms of my own DNA journey and indeed almost to the beginnings of the human race.
Please note: I couldn’t even pretend to be an expert in what follows. There’s a reading list at the end if you want to explore further.
Meeting the Izzards
Back in February 2013 I watched a two-part BBC series called Meet the Izzards. Actor/ comedian/ campaigner Eddie Izzard took two DNA tests: a mitochondrial test which would follow his mother’s mother’s mother’s etc line all the way back through time; and a Y-chromosomal DNA test which would reveal the same for his paternal line. At the time of writing, the programmes are available on YouTube:
Mitochondrial and Y-chromosome DNA inheritance
We all receive mitochondrial DNA (mtDNA) from our mothers, but only females pass it on to their own children. Sons receive it, but can’t pass it on. Y-DNA, on the other hand, passes only from father to sons. The daughters never receive it.
So my brother and I can each take a mitochondrial test, and they would reveal exactly the same information about our maternal line deep origins. But only I have passed it on. His children have received the mitochondrial DNA of their own mother. On the other hand, only my brother received our father’s Y-DNA. He has passed that on to his sons but not to his daughter. My sons have received the Y-DNA of their father (but not, of course, his mtDNA). If I want to find out about my direct paternal line, I have to ask a male relative either in my direct paternal line or descended directly from that line to do it for me – my brother, nephew, father, grandfather, paternal uncle, a cousin who is the son of a paternal uncle, etc.
As a man, Eddie Izzard was able to take both tests: the mitochondrial and the Y-chromosomal. It was his journey that inspired me to embark on my own.
Haplogroups and ‘clan mothers’
After watching the TV programmes I read Bryan Sykes’ book: The Seven Daughters of Eve. Fellow of Wolfson College, and Emeritus Professor of Human Genetics at the University of Oxford, Sykes was a pioneer in the extraction of mitochondrial DNA from ancient human remains. In this book, aimed at the non-scientific reader, he outlines how he did this, as well as some of the research findings flowing from that:
We all have one common ancestral mother. She lived 200,000 years ago in Africa, and is referred to in DNA circles as ‘Mitochondrial Eve’. We are also all descended from a common ancestral father. He too lived in Africa, and is referred to as Y-chromosome Adam. (DNA from Y chromosomes is harder to extract and was developed a little later, but there are parallel findings to the following for Y-chromosome testing.)
About 60,000 years ago, some of Mitochondrial Eve’s descendants crossed over the Red Sea, leaving Africa for the first time. So started the worldwide human diaspora. Some of our forebears headed north, some east, some west – obviously a gradual migration, taking thousands of years. It wasn’t until about 40,000 years ago that the first anatomically modern human beings entered what we now call Europe, but they came via different routes. Thanks to DNA, scientists are now able to trace their progress.
Sykes found that the vast majority of (indigenous) modern Europeans can trace their mitochondrial DNA to one of seven women – these are the ‘Seven Daughters of Eve’ referred to in the title of his book. Scientifically, the terminology is that modern Europeans fall into one of seven mitochondrial haplogroups: U, X, H, V, T, K and J. However, since the point of Sykes’s book was to bring the science to a more general audience, he focuses not on the scientific terminology of seven ‘haplogroups’, but on those seven women living way back in the distant past, with whom these seven distinct haplogroups originated. He even gives them names, each one corresponding to the letter of the haplogroup she heads up: Ursula corresponds to Haplogroup U, Xenia to Haplogroup X, Helena to H, Velda (V), Tara (T), Katrine (K) and Jasmine corresponds to Haplogroup J. While each of these women was a descendant of our common mother ‘Mitochondrial Eve’, if you are of indigenous European descent, one of these seven women will be your (many times) great grandmother.
Later, with additional data from Scandinavia and Eastern Europe, Sykes added Ulrike as an 8th clan mother/ haplogroup. But the science continues to develop, and it seems the precise number and arrangement of haplogroups is not yet fixed. There are also an additional 29 haplogroups worldwide, all with ‘clan mothers’ named by Sykes and each associated with a different geographical area or native people. You can read more about this here.
The science bit
It is the mitochondrial DNA we receive that identifies each of us as belonging to one of these haplogroups, and this mitochondrial genome usually passes unchanged from one generation to the next. Periodically, however, it mutates. (This isn’t a bad thing; it just means it changes.) It is this mutated (slightly changed) version that will now be passed on by that line, and all descendants of this woman from this point onwards will be distinguishable as a different branch (or ‘subclade’) of the line. These mutations, or ‘markers’ are what DNA specialists look for when analysing the mitochondrial genome for ancestry purposes. By comparing these markers with other testers and with the DNA signatures typical of people in particular geographical regions, and then by calculating how far back in time each mutation occurred, it’s possible to suggest the broad migratory routes our ancestors appear to have taken to get from Africa 60,000 years ago to where we are now. What this means is that rather than simply being of haplogroup U, X, J, etc, we are each identifiable as part of a subclade, such as J1 or J2, and even smaller sub-groupings than that, like J2a1a1a2. (i.e. everyone in haplogroup J2 is descended from the one same many-times grandmother, but if you share a subclade with another person, like J2a1a1a2, then you also share a much closer common maternal ancestor.)
Combining DNA research with other disciplines
What really fascinates me about all this is how DNA evidence is now used in combination with archaeology, palaeontology, anthropology, linguistics and other disciplines to push back the frontiers of knowledge of our deep ancestry. Here are some examples:
- DNA has proven conclusively that although early modern humans and Neanderthals lived separately, about 55,000 years ago they did produce some joint offspring. Consequently, today the average European has just less than 2% Neanderthal DNA, while people whose origins lie in Asia, Australia and the Americas have an average of just over 2% Neanderthal DNA. It’s possible that this is where we get (amongst other traits) our straight hair and our ability to retain weight (– this was a good thing 55,000 years ago).
- Mitochondrial DNA has helped to solve a mystery about the apparent annihilation of Celtic as the language of Britain prior to the Anglo-Saxon invasions. The almost complete disappearance of the Celtic language from England, leaving it only in the West of the British Isles, was suggestive of the massacring of the people. And yet DNA shows this did not happen. Only the language was lost; the people remained.
- Comparisons of mtDNA and Y-DNA in the British Isles has also shown that not all Viking invasions were violent. If the reverse were true, there would be a great deal of Viking Y-DNA and very little Viking mitochondrial amongst the British people, but this is not the case. Therefore many Viking incomers were couples who came peaceably and settled.
- It was mtDNA sequencing that proved the skeleton found under a car park in Leicester was that of King Richard III. His mitochondrial DNA, as received from their mother, was passed down through the female line from his sister to two relatives alive today.
Can this help with our documented family trees?
The autosomal DNA test – the one usually taken by people researching their family trees – gives us a complete 360-degree picture of the bits of DNA we’ve inherited from each ancestor of the last five generations or so. Mitochondrial and Y-chromosome testing won’t help with this. Since both types of DNA pass largely unchanged down the male or female line, our mitochondrial and/or Y-DNA links us back thousands of years to specific individual women and men whose names we will never know. An mtDNA test, then, will verify that at some point we shared an ancestral mother, but the very slow mutation rate of this type of DNA means that it may be possible only to narrow this person down to a 500-year period. A Y-chromosome test has a slight advantage in that it passes along exactly the same route as the surname. Assuming, then, that there have been no adoptions, no elective name changes and no ‘non-paternity events’, a Y-DNA tester can expect to find they match with others of the same surname. The sharing of the Y-DNA shows that they are definitely related on the paternal line.
Certainly for me, the decision to take a mtDNA test was separate to my interest in my family tree, stemming from a curiosity about my deep ancestral origins.
Trust me – these are all aimed at non-scientists! (But I recommend starting with Meet the Izzards on YouTube.)
Bryan Sykes: The Seven Daughters Of Eve
Bryan Sykes: Blood of the Isles – outlining how DNA has contributed to understanding the nature and implications of successive invasions of the British Isles.
Sykes has also written a number of other books about various aspects of DNA.
Karin Bojs: My European Family: The First 54,000 Years – a fascinating, and up to date account of how genealogists, geneticists, anthropologists, linguists and other experts are working together to make sense of the deep history of the human family. Karin Bojs is science editor of a Swedish newspaper, and in this work uses the general information to make sense of not only her own roots but also those of Sweden and Europeans more generally.
Blaine T. Bettinger: The Family Tree Guide to DNA Testing and Genetic Genealogy – aimed at genealogists who are not scientists, this book covers mitochondrial, Y-chromosomal, autosomal and X-chromosonal DNA, explaining the science and then, importantly, how we can apply the results in our family research. Blaine T. Bettinger also has a blog and a YouTube channel. He has helped me to make sense of a lot of this DNA stuff, and I’ll definitely be mentioning him again when I write about autosomal DNA for genealogy in the future.