July 2016
Preface
Because Mitochondrial DNA (mtDNA) represents such a small part of one’s ancestry, to begin with, I decided not to pursue tests beyond the basic one. However, Family Tree DNA (FTDNA) offered a special on testing mtDNA so I changed my mind and I now have full sequence results.
mtDNA
All the cells of higher organisms contain structures, mitochondria, which have their own independent DNA. Mitochondria are the cell’s “power house” and they generate most of the cell's supply of adenosine triphosphate, used as a source of chemical energy. Bacterial DNA is very similar to mtDNA and one theory of the origin of mitochondria is that they were originally bacteria that formed a symbiotic relationship with other early cells (specifically, eukaryotic cells). Mitochondria contain a single chromosome so there is no recombination of the genetic material and changes are from mutations only.
Mutations occur at random and were thought to be at a consistent average rate, giving a “clock” allowing when mutations occurred to be estimated. However, in practice mutations are very variable and estimated mutation rates differ by an order of magnitude (see wikipedia). The mutations are used to define groups of descendants: “haplotypes” or “haplogroups.” The first method of typing mtDNA looked at sequences of nucleotide pairs and inferred the specific differences due to mutations. The groups obtained by this method were called haplotypes and this was the first test I did. Subsequently it has proved possible to explicitly identify individual nucleotide changes (“single nucleotide polymorphisms,” SNPs for short). In this case the resultant groups are called haplogroups. My most recent results are of the latter type.
In primates (including humans), mtDNA comes only from the mother (i.e. from the ovum or egg cell). Hence it is passed down through the mother’s line only; both sons and daughters have the same mtDNA but only the daughters pass it on to their offspring. In our family (descendants of Sarah Ann Steels), the mothers I know about are:
Elizabeth, wife of William Holgate, born Little Casterton c1791 died 1872
Mary Holgate born Surfleet 1822 died 1862
Elizabeth Dunmore born Eye 1861 died 1905
Sarah Ann Steels born Eye 1885 died 1971
Elsie Tiggerdine born Eye 1913 died 2007
& Hetty Tiggerdine born Eye 1915 died 2010
Janet Godfrey born Newborough 1941
Karan Elaine Tasker born Peterborough 1966
All of these women and their children have the same mtDNA but the line has now died out with only males at the ends of the various branches.
All modern humans are thought to have descended from one woman “Mitochrondial Eve” who lived 100-200 thousand years ago in Africa. The main haplogroups have been labelled with a letter of the alphabet and Eve’s is “L”. Bryan Sykes, who first got me interested in this, designated seven main European haplogroups which he describes in his book “The Seven Daughters of Eve”. Our main haplogroup is “H,” Sykes’s “Helena” which is the most common group in Europe. My latest test gives an end haplogoup for us of H2a1. The figure below is an abbreviated diagram showing the various groups descended from Eve.
H2a1
H2a1 is not that common and these days seems to be mostly in Eastern Europe, Northern Caucasus and Central Asia (according to Eupedia). I joined the FTDNA mtDNA H project and of nearly 9,600 members, only 67 are H2a1. There is a map of some of the European ones below.
Eupedia and Ancestral Journeys have tables of the mtDNA haplogroups of people from many ages found in archaeological digs. The earliest H2a1 record is from a single male from Samara, Russia dating from the late Neolithic - early Bronze Age, 6,700-6,000 BP (before present). Samara is on a bend in the Volga River marked on the map below with a red “S.” Around 2,000 years later, there are samples from the Early Catacombs culture in Lisichansk, Eastern Ukraine (a red “L” on the map). There are roughly contemporary samples from Saxony in Germany and more from Hungary about 1,000 years later in the middle of the Bronze age in Europe (marked with red “B” on the map). We also have a probable maternal autosomal link to Bronze age Eastern Europe (Hungary) which shows up in most of us (see Origins). The mtDNA of the British Isle Bronze Age population seems to have been mostly U.
The H haplogroup probably originated in SW Asia (the present Middle East excluding Egypt) 20,000 to 25,000 BP. The H2 mutation seems to have appeared in the Caucasus (present day Azerbaijan and Georgia) and H2a1 north of the Caucasus on the vast steppes stretching from the northern shores of the Black Sea as far east as the Caspian Sea, from Moldova and western Ukraine to western Kazakhstan. After the Bronze Age they spread out west and north into Europe.
Summary
During the last ice age our distant maternal ancestor lived in what is now the Middle East. After the ice retreated, her descendants moved across the Caucasus to the Pontic Steppes and then west to Eastern Europe. They may have arrived in Britain with any of the waves of immigrants from the Bronze age to those seeking refuge from Catholic persecution in the 16th and 17th centuries.