It is only simple arithmetic but it seems to me quite remarkable that the long journey from the dawn of anatomically modern humans (AMH) some 250,000 years ago, when considered along any particular line of descent, contains not more than some 12,000 individuals. So the right 12,000 names, if I knew them, would suffice to describe all the individuals on any specific line of descent from my origins as an anatomically modern human. Twelve thousand is not so great a number of people. It is less than the population of the little town I live in and it is a number that would be comfortably handled by even quite a small database. I even hear that some people boast more than 12,000 followers on Twitter and others have more than 12,000 “friends” on Facebook! It does not take many minutes to set up an Excel sheet with 12,000 line items, each line then representing one individual on one of my particular lines of descent.
I was 34 years old when my eldest son was born. My father was 37 when I was born. His father – my grandfather – was about 35 when he was born. With his father (my great, grand-father who was born in about 1850) who was about 26 when he was born, I come to the end of the written or verbal history of my descent through my father that is available to me. I take a “generation” to be the time between succeeding births on any direct line of descent. The length of my preceding generations has, no doubt, varied and was most likely distinctly shorter in the past. In my particular case I arbitrarily take the average duration of my preceding generations to have been 21.72 years long. It is a plausible number and while it cannot be proved it is also difficult to refute.
When delving into the fascinating – but arcane – fields of paleo-anthropology and genetics and biology and archeology, I find I am constantly trying to create a narrative which hangs together and looking for the little details which can enable me to personalise and identify with the narrative. It is a search for little “hooks” onto which I can hang my “hats” of understanding. And one such “hook” which both anchors and enables my imagination is that when looked at in the perspective of individuals in a particular line of descent, the ancient past is not as intangible and unreachable as it might seem.
And so let us focus on individuals within the big picture. Around 190,000 – 200,000 years ago, it seems our most recent common matrilineal ancestor – for all 7 billion of us – Mitochondrial Eve – held court in Central/East Africa. I call her M’ytevi. Along my matrilineal line of descent it has needed only 8747 women (give or take a few) to span the generations from M’ytevi (i.e. from my 8,748th Ancestral Generation – AG8748) to my mother. Similarly our most recent common patrilineal ancestor Y’chradam (for Y-chromosomal Adam) can be traced back also to Africa and to around 142,000 years before present (ybp). Here, it has taken just 6,538 men in an unbroken father-to-son line from Y’chradam (AG6538) to me.
And whether it was my long-removed ancestor from my Ancestral Generation AG5064 or one from Ancestral Generation AG 3220 who crossed the Bab-el-Mandeb is uncertain. But what is certain is that my ancestral patrilineal-father from AG6000 lived in central or East Africa. I call him M’rrgan.
This blog is for my speculations about the 6,000 generations since M’rrgan.