Genetic Genealogy
Introduction
A number of years ago my brother, Geoffrey Brian Sewards, spent a lot of time and effort in tracing the Sewards' family tree back as far as he was able, to the 17th Century. At this point he had exhausted the available written records, which only date from the 16thC and are rather incomplete in the 16 and 17th C. Several years later, while in Salt Lake City in the USA, I visited the Mormon Genealogical Museum and tried to extend the search further back in time using the enormous stock of records held in the Museum. I was able to find some data which extended the ancestry back 100 years or so, but that was it. The Anglo-Saxon Chronicle contains some hints about earlier possible ancestors, as does the Domesday Book, but these do not contain detailed information.
DNA Testing
A few years ago, I read the book Out of Eden by Stephen Oppenheimer, published in 2003, which discussed the peopling of the world from the viewpoint of genetic genealogy, and later his other books Eden in the East (1998) and The Origins of the British (2006), together with books on the same subject by Spencer Wells, Chris Stringer and Matt Ridley. I was fascinated by the results of the research that had been carried out and the completely new light that it cast on the movements of man over the past 100,000 years. When DNA testing became economically available, I had my own Y-chromosome DNA tested by the Geographical Society's Genographic Project which revealed that my DNA was of the group R1b1a1. I subsequently had another more detailed test conducted by Family Tree DNA (FTDNA) which resulted in the group R1b1a2a1a1b4 or R-L21 using the new nomenclature. These groups are called haplogroups or sub-clades. Since then I have had further tests which revealed haplogroup Z-253 and then CTS 4314.
Male Chromosome
It is now generally known that all human beings on earth have one single male ancestor, known as 'Adam', and in addition, all peoples outside of Africa have a second unique male ancestor known as 'Out of Africa Adam'. It is now believed that all peoples out of Africa are descended from a small group of people who crossed the Red Sea from Africa to Asia between 80,000 and 50,000 years ago, probably in two waves. Each group must have been small, probably no more than a couple of hundred individuals, the descendants of whom have populated the world. (The fact that everyone is now found to have a single unique ancestor does not mean that he was the only male but simply that all other male lines have died out.) From time to time a child is born with a mutation in his/her DNA, which means that he or she has DNA which is slightly different from that of the parents, and this changed DNA is passed on to future generations. The change may be either in the number of repeats of a pattern (Short Tandem Repeat or STR), or the change of one base for another (Single Nucleotide Polymorphism or SNP). The existence of these mutations can be used as markers to identify the lines of descent of individuals, and by various means the approximate dates of each mutation can be obtained, allowing the past movements of groups of people to be estimated. In the group identifiers (haplogroups) given above, each pair of letter/number indicates a specific mutation which can be identified by DNA analysis, showing that in my case, there were 6 defining mutations in the line of ancestry starting at the ancestor called R who lived some 30,000 years ago.
Mitochondrial DNA
In addition to the 'Adams', there was of course an 'Eve', who contributes the DNA called mitochondrial or mtDNA, which is inherited down the female line, from mother to daughter. Males do have mtDNA but it is not passed down the male line. mtDNA also has mutations which can be identified in a similar manner to male Y-chromosome DNA described above. However, the rate of mutation in mtDNA is less than that in the male Y-chromosome DNA, which makes it a less precise tool for dating and identification. I have not yet had my DNA tested for mtDNA.
Historical Dates for Mutations
The ancestor called 'R' lived about 30,000 years before the present (bp) and was probably a descendant of the second wave of migrations out of Africa which took place around 50,000 years bp. This group of emigrants is believed to have taken the route up the eastern coast of the Red Sea whereas the first group took the coastal route towards India, some 20,000 years earlier. The second group seem to have ended up in Anatolia or the Fertile Crescent from where they dispersed groups into the steppes, to northern India, to Mongolia and to the Balkans. The first mutation on a descendant of R is called M17 and occurred about 25,000 years bp giving rise to the sub-clades R1a and R1b. Another event occurred in 18,000 years bp in the region of the Black Sea when the marker P25 gave rise to the sub-clade R1b1. From this point until about 9500 years bp the clan was located in the region of the Black Sea, Caucasus, and the Pontic-Caspian steppes when the marker M269 announced the sub-clade R1b1a2. At this time the group formed part of the peoples known as the Proto-Indo-Europeans who spoke the prototype of the Indo-European language which has formed the basis of so many of the worlds tongues, including all the European languages except Basque. These people occupied the territory from Anatolia to the Pontic-Caspian steppes, moving about summer/winter and with climate variations due to the end of the Ice Age. They invented the wheeled wagon and domesticated the horse. In 7000 years bp, R1b1a2a1 appeared (L51) and in 6000 years bp R1b1a2a1a1 with L11. After this date, the Indo-Europeans moved along the Danube toward central Europe, from whence groups dispersed to Ireland, England, Northern France, Denmark, and Norway. At 4000 years bp, the marker L21 appeared, announcing the subclade R1b1a2a1a1b4, also known as R-L21, but it is not known at the mement where L21 was born. The subsequent analyses have carried this on to sub-clades Z-253 and now CTS4314 and then Z-2185, the latter living about 2000 years BP. My ancestor may have reached England direct from central Europe (Germany, Belgium), or via Denmark (Schleswig Holstein), via Norway (Viking invasions) or other possible routes. At present, I have no information on which route may have been taken, but further analysis of my DNA sample may refine this. Note that R-L21 is the most common haplogroup in European populations. At present Z-2185 is a fairly new SNP and not enough data exists to indicate his location or refine the date.
Alan Sewards' Haplogroup
R1b1a2a1a1b4 (R-L21), Z-253, CTS-4314, Z-2185
Useful Links or References
http://www.eupedia.com/europe/Haplogroup_R1b_Y-DNA.shtml
Oppenheimer, Stephen: Eden in the East
Oppenheimer, Stephen: The Origins of the British
Wells, Spencer: The Journey of Man - A Genetic Odyssey
Wells, Spencer: Deep Ancestry
Ridley, Matt: Genome
Stringer, Chris: Homo Britannicus
Cavalli-Sforza, Luigi Luca: Genes, Peoples and Languages.