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DNA

The human body consists of 60 thousand billion cells (eg white blood cells, muscle cells, or cheek cells) of which nearly every single cell contains our entire genetic information, the DNA. Inside the cell, DNA is found inside the nucleus (chromosomal DNA, consisting of autosomal DNA, X chromosomal DNA and Y chromosomal DNA) and outside the nucleus (mitochondrial DNA).

Our autosomal DNA is inherited from both parents, but Y-chromosomal DNA (Y-DNA) is inherited only from father to son, and mitochondrial DNA (mtDNA) is inherited only from our mother.

Mitochondrial DNA

Shortly after the process of fertilization, the sperms' mitochondria die away, and the embryo is only left with maternal mitochondria. As such, we share the same mtDNA as our brothers and sisters, but not our fathers.

MtDNA is also passed down nearly unchanged from generation to generation. So we share the same mtDNA-type as our mother, our maternal grandmother, our maternal great-grandmother and so on. In fact the exact same mtDNA code will track our direct genetic line back until the point at which a natural mutation in the mtDNA code occurred - on average about every 20,000 years.

The logical extension of this is that we all ultimately trace back to one woman who lived around 150,000 years ago, who is commonly referred to as Mitochondrial Eve. Since that time, Mitochondrial Eve's descendants have gradually populated the entire globe, with the original founder group spreading geographically and branching genetically in the course of the millennia, leaving genetic footprints - or mutations in their mtDNA - at regular intervals wherever they went. These prehistoric branching events can be read in the ancient mutations of our mtDNA like in a history book. See Ancient Migrations for more about how we can trace the expansion of the world's stone age population over time.

Roots for Real uses these advances in genetic understanding and laboratory techniques to help identify your maternal lineage through our mtDNA tracing service. By analysing and comparing your own distinct mtDNA with our database of many thousands of other mtDNA samples from all over the world, we can tell you much about your ancestry.

Mitochondrial Eve

mtDNA has now been used to trace back through all of these natural mutations to the origins of all modern human existence to a woman known poetically as 'Mitochondrial Eve', who lived around 150,000 years ago.

'Mitochondrial Eve' is most recent common ancestor of all humans alive on Earth today with respect to our matrilineal descent. Note that this does not necessarily mean that she was the only woman alive at that time. Presumably there were other females alive at that time, but her lineage is the only female lineage to have survived through to the modern day. Since then, as people have migrated across and out of Africa (see Ancient Migrations), their mtDNA has changed slightly owing to very occasional mutations in the genetic structure, offering us the wealth of different mtDNA types now.

The concept of 'Mitochondrial Eve' is in some sense a purely mathematical fact. Consider the number of all women living on earth today, 'A'. Now consider the number of the mothers of all women living on earth today, 'B'. Obviously, B is either the same size or less than A. As you go back through the generations, B reduces, ultimately to one woman. That woman is popularly referred to as Mitochondrial Eve.

Y chromosomal Adam

Because the Y chromosome is passed down exclusively from father to son, all human Y chromosomes today trace back to a single prehistoric father, "Y chromosomal Adam", whose time we can date to more than 100,000 years ago using our statistical methods (Forster et al. 2000).

Just like mtDNA, the original Y chromosome has mutated its DNA naturally over the generations and these new Y types have settled in various parts of the world in prehistory. By determining your present Y-type and searching the worldwide Y database, Roots for Real can give you a good idea where in the world your father's lineage is generally found today.

Additionally, family researchers (genealogists) who wish to know whether two people with the same surname are related, are increasingly using Y chromosomal tests. This is possible because in many cultures, family names or surnames are passed down by the father just like the Y chromosome.

In such cases, two Y tests are needed: one Y test for oneself, and Y test for the person with the same surname who is suspected to be related. All that is then needed is to compare whether the two Y results are identical.

For people wishing to confirm their Jewish priestly descent, the Y test is also relevant. The priestly caste of the Cohanim are thought to have the same Y chromosome as the biblical Moses, because Aaron, Moses' brother, founded this priesthood, whose duties traditionally pass from father to son. The Cohanim Y type identified in groundbreaking analysis by the team of Prof. David Goldstein and colleagues agrees with the biblical tradition, and a simple Y test using our database search can confirm whether a Cohen male indeed carries the Cohen Y type.

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