Monday, 23 April 2012
Who Are we? What can DNA tell us?
Last week I gave a talk to the Caithness Family History Society entitled Who are we? What can DNA tell us?, based on my own experience of having my DNA analysed and reading around the subject, mainly in the writings of Professor Bryan Sykes of Oxford University. The above question is often asked as the ancestral trail goes cold into the period before records were kept at least on ordinary folk. In my case the Scottish Old Parish Church records get me back to the early/mid 1700's on my Calder line but before that, history is silent.
I began my talk by taking people back to prehistory to the time when the British Isles were repopulated after the last ice age receeded, about 12,000 years ago. However British Isles isn't quite correct. Because so much water was locked up in ice, sea levels were much lower and there was continuous land over much of the North Sea connecting us to the European land mass to the east and to Ireland in the west enabling the earliest settlers to walk in (Eurosceptics please note). DNA analysis of the European population has clarified that most of the pre-empire citizens of the British Isles are descendants of those hunter/gatherers who walked in over the land bridge or arrived by sea a bit later. To them we can add Danes/Saxons who came in the middle of the first millenium and settled especially in East Anglia. After that the only major addition is the Vikings who settled particularly in Shetland, Orkney and Northern Scotland. DNA analysis of both males and females in the north confirms that there are about equal numbers in the population suggesting that the Vikings took their womenfolk with them and that their reputation for rape and pillage does not reflect the full picture of how they operated.
At the level of the science, the main two things we need to understand is that all males have a Y-Chromosome which is transmitted unchanged from father to son down the ages and is therefore an excellent tracer of male lines. Similarly, mitochondrial DNA is passed unchanged from mothers to daughters and sons unchanged and hence is an excellent tracer of female lines.
Professor Sykes has done a good job of de-mystifying the dry science by giving names to the major clans of male and female lines that have similar DNA and therefore share a common ancestor in the past. My male line is Oisin (pronounced O'Sheen), the most common in Scotland covering 73% of the male population. At the level at which my DNA has been studied, I can look up lists of males who share the same Y-chromosome DNA. These are males with whom I share a common ancestor who lived about 1500 years ago, long before surnames were used. Many of them are British, or Americans who emigrated from Britain. However there are a few South American males with Spanish or Portuguese names, a relic of British sailors, soldiers and traders cohabiting with indigenous females. This is apparently a worldwide phenomenon. Eg 20% of Maori males have European Y-Chromosomes.
DNA analysis has also put facts behind many historic myths. It is estimated that 16 million Asian males share a single Y-Chromosome. This is thought to be the ultimate footprint of Genkhis Khan's Mongol empire and reflects the brutality of his conquest, eliminating local males and taking their women.
On the West Coast of Scotland, the clans MacDonald, Mc Dougall and Macalister all claim descent from the Celtic hero, Somerled, who is credited with driving the Vikings out of Argyll and the Hebrides. Y-Chromosome DNA analysis has proven the link in that many men sharing these surnames and all the current clan chiefs share a single rare chromosome. However the chromosome is a Viking type so Somerled's paternity must have included Vikings at some point.
Professor Sykes did a major study on men with his own surname and came to the conclusion that 50% of males with that surname have the same Y-Chromosome and are descended from one Mr Sykes, who took the name in the 1100's when surnames became obligatory (for taxation!). His study highlights another interesting facet of the human condition. The other 50% of the Sykes males who don't share the same chromosome result from what he euphemistically calls non patrimonial events where the link between surname and DNA gets broken.I'll leave you to work that out for youtrself.
On the female side I'm a Helena, descended from hunter/gatherers who left the Languedoc in France to make their way north after the Ice Age.
Finally, It is tempting to imagine that all the Caithness Calders are descended from one individual. In the early records they are concentrated in two areas of the county. We need a county wide DNA study of Calder males to find out.
The Stuart Agenda by Alan Calder. E-book and paperback at amazon.com. E-book at amazon.co.uk