In a previous post, I used an analysis of my Y chromosome DNA to trace the journey of my paternal ancestors from Y-chromosomal Adam, who lived in West Africa around 275,000 years ago (275 kya), to the founder of the R1b sub-haplogroup R-L23, who was born on the Caspian around 4,400 BC (6.4 kya). In this post, I continue my paternal ancestral journey to the most recently identified haplogroup founder: a Celtiberian living in what is now Portugal around 510 BCE. The sequence of Y SNPs defining my haplotree are shown in the following map. It summarizes this journey from R-L23 (4,400 BCE) to the most recent haplogroup founder (510 BCE), and continues on from the map published in the previous post.
There is an immense amount of recent research on European Bronze Age genetics and migrations and a very considerable unfinished debate on how to interpret the evidence. New evidence is being published almost weekly, as increasing numbers of ancient European remains are analysed and Y haplogroup identified. So this post will only aim to describe the big picture as best I can summarize it, and details and perhaps even some of the big picture will likely change in the future.
In earlier posts, I discussed how I have used an analysis of my Y chromosome DNA to identify my paternal ancestors all the way back to Y-chromosomal Adam, the most recent common ancestor of all men alive today. The following map summarizes my Y haplogroup ancestors from Y-chromosomal Adam down to those who left Africa around 70 thousand years ago (70 kya) and headed east through India and South East Asia and then up through China into ice age Siberia and then across to the Ukrainian steppeland north of the Black Sea.
I was originally going to continue this story all the way across Europe to the Iberian Peninsula and up to Ireland and Scotland, but I will keep that for a later post. I have discovered that there is an immense amount of recent research on European Bronze Age genetics and migrations and a very considerable unfinished debate on how to interpret the evidence. So it may take me a little while to come to grips with it. (A follow-up post is now available at my-paternal-ancestors-european-journey-the-caspian-steppes-to-celtiberia)
The human Y chromosome is a male-specific sex chromosome. When mutations (errors in the copying process) arise in the Y chromosome, they are passed down directly from father to son in a direct male line of descent and define a tree of Y “haplogroups”. The mutations on the Y chromosome can thus be used to trace our paternal ancestors all the way back to the most recent common paternal ancestor of all men alive today, Y chromosomal Adam.
When I first got interested in genetic genealogy around 2010, I had my DNA tested by the National Genographic Project, funded by the National Geographic to collect over a million DNA samples to map the patterns of human migration across the world. This project measured mutations known as short tandem repeats (STRs) at 12 sites, and gave a statistical prediction of my Y-haplogroup, R1b (M343) and subclade R-M269. A year later I upgraded my Y-DNA analysis to 44 STRs with Ancestry.com. At the time, I decided that I would wait for the technology to improve and the cost to drop and do a more comprehensive test which would definitively determine my Y haplogroup.
And so last year I did the Big Y-700 test with FamilyTreeDNA which examines 700 short tandem repeats, and over 200,000 single-nucleotide polymorphisms(SNPs) identifying known haplogroups as well as millions of locations where there may be new branch markers on the Y chromosome. This company claims to have the world’s largest genealogical YDNA database with over 2 million people included.
Y-chromosomal Adam is the name given to the patrilineal most recent common ancestor (MRCA) of modern humans. In other words, he was the man from whom all living humans today descend, on their father’s side, and through the fathers of those fathers and so on, back until all lines converge on one person. He is the male counterpart of Mitochondrial Eve, who,lived in north-western Botwsana around 177,000 years ago (confidence interval ± 11,300 years).
When I did my first Y-DNA test in 2012 with the National Geographic’s National Genographic Project, it gave a date of 60,000 years ago (60 kya) for Y-chromosomal Adam. This was already outdated, as other recent estimates around that time gave dates ranging from 120 to 160 kya. By definition, it is not necessary and highly unlikely that Y-chromosomal Adam and Mitochondrial Eve lived at the same time or in the same location.
However, in 2013 scientists announced the discovery of an extremely ancient Y DNA haplogroup from a sample submitted for an African-American man in the USA. Y-chromosomal haplogroups are defined by mutations in the non-recombing portions of DNA from the Y chromosome. These mutations accumulate at the rate of roughly two per generation. The accumulation of mutations in the descendants of Y-chromosomal Adam allow us to map out the major branches of the family tree in terms of Y-haplogroups. This discovery adds a completely new branch to the Y-DNA family tree and pushes back the age of Y-chromosomal Adam to around 250 to 300 kya.