By Megan Lane
BBC News Magazine
A family tree researched by conventional methods can only go back so far before patchy records stymie progress. Now amateur genealogists are turning to DNA testing to trace their ancestry. But how much can this tell us about where we come from?
My family tree is rooted in Scotland, as far back as my mother has managed to trace the branches. But having reached the early 1800s, the trail has gone cold. There are blanks, dead-ends and inconsistencies thanks to lost, absent or incomplete written records.
It's a frustration shared with amateur genealogists the world over. But a record that can never be lost or incomplete is now available to those who wonder "where do I come from?" - their DNA. Thanks to recent breakthroughs in genetic testing, scientists claim they can trace our origins back tens of thousands of years - for a price.
US firms such as Family Tree DNA and DNAPrint Genomics offer services such as telling you if you are related to Native Americans and other racial groups. And in the UK, several operators offer a range of DNA tests for ancestry research.
For about £180, the scientists at Oxford Ancestors will trace ancient maternal ancestry by testing mitochondrial DNA (mtDNA), which is passed down from mother to child and changes little over time. It is this test which I have taken.
The firm is the brainchild of the Oxford University geneticist Bryan Sykes, who five years ago published research showing that everyone of European extraction could trace their ancestry back to one of seven women who lived 40,000 years ago. Such was the demand from the public to know which of the "seven daughters of Eve" they were descended from, Professor Sykes spotted a business opportunity.
His past research has used DNA to chart human evolution or to solve genetic riddles. It was he who proved the Polynesians are of Asian, not South American, descent. More recently, he researched the strong genetic connections among people with the same surname.
Back to my roots
What can such a test tell me about my ancestry? As a white New Zealander, I'm highly likely to be descended from one of the seven daughters of Eve. But if, say, a maternal ancestor had had a hitherto secret liaison with a Maori, this test could result in a completely different clan being identified.
To emphasise that these ancient clan mothers were real people, the team at Oxford Ancestors has given each woman a name and an imagined biography.
The lab processes my DNA
While there were obviously many other women alive at the time, these are the only ones with direct descendants living today, Professor Sykes says.
"The others in their clan - or their descendants - either had no children or bore only sons, and so could not pass on their mtDNA."
The DNA test itself is straightforward. A small mouth swab, not dissimilar to a mascara brush, is rubbed inside the check, and the sample sent for analysis. From this a section of mtDNA 400 pairs long is extracted, and the "spelling" of this sequence compared with the many thousands in the Oxford Ancestors' database.
This shows my maternal ancestor to be Ursula, the oldest of the seven daughters of Eve, who lived 45,000 years ago in northern Greece. Her people were cave-dwelling hunter-gatherers, tall and slender by comparison to the Neanderthals with whom they shared the land for another 20,000 years. The first European cave paintings date from this period.
She is an ancient ancestor I share with one in 10 people of European extraction, particularly among those from Scandinavia and western Britain (which of course makes for an impossibly large, complex and meaningless family tree).
Europeans mostly come from one of seven women
About half are from Helena, who lived in the Pyrenees 20,000 years ago
Among non-Europeans, 29 such clans have been identified
These include 12 among those of African origin
Four among Native Americans
And nine among Japanese
The historian Lord Renfrew has said that using DNA analysis gives a skewed picture as it misses out everyone else who has contributed to our genetic make-up. "[Looking back] three generations reveals eight great-grandparents, 10 generations exposes more than 1,000 ancestors. Each one of these individuals has contributed to your gene pool, but by studying only the Y chromosome and mitochondrial DNA, you reveal only two lineages: your father's father 10 times removed, and your mother's mother 10 times removed."
Thus if the imagined liaison was on my father's side - say, between his great-grandfather and a Maori woman - the DNA tests wouldn't pick that up as my mtDNA is from my mother.
What is of more interest is that my DNA sequence is an exact match for one other on the Oxford Ancestors' database - which means we're closely related, and may be able to add to each others' family trees should we make contact - and a near match to numerous others, which means a family connection some time in the past few hundred years.
"Let's take a look where they live," says Prof Sykes, tapping into the database. "Hmmm, pretty Celtic. Most are in Scotland, the Hebrides, the west side of the UK."
mtDNA passes from mother to child
But while I know how my near forebears made their way across the world a century ago, how did their ancestors get to Britain from northern Greece? What is known about the major migrations and dispersals of the past provides rich material for imagining past lives. Gradually they moved westward, first to France and the Iberian peninsula, and eventually settling in what is now Scotland, Wales and Ireland several thousand years ago.
Which is pretty much what many millions of people - be they Scottish, American, Australian and so on - can conclude about their ancestry.