Our common ancestor isn't so far removed

I was fascinated by this article on when the last person we are all decended from lived.

No wonder we argue so freely here we’re just another disfunctional family! :smiley:

Oh, I can hear it now.

I’m curious how long before I hear this in the religious circles.

I’m having a little trouble following that reasoning. Are they saying that, say, 5000 years ago one person was all our ancestor? Or everyone alive then is our ancestor?

Means everyone alive then who survived to produce at least one child are ancestral to everyone on Earth. This is often asked by newbie genealogists – since your ancestors double every generation you go back (2 parents, 4 grandparents, 8 great-grandparents, etc.) once you get back a few thousand years you should have millions of ancestors, far more people than were alive at the time. How can this be? The answer is pedigree collapse – cousins marrying cousins, so you’re descended from the same sets of ancestors multiple times.

Probably, most people by now are descended from Charlemagne, Confucius, and Muhammad. The only holdouts would be in extremely isolated populations, like the Australian Aborigines, and the remaining fullblooded American Indians, but even these populations are mixing with outsiders and have been for the past couple of hundred years.

Just as interesting is Mitochondrial Eve and Y-Chromosome Adam – names given to the common ancestors of, respectively, every female and male on Earth. Even woman inherits her mtDNA from her mother, and every man his Y-Chromosome from his father. Amusingly, “Adam” and “Eve” did not live at the same time. The common female-line ancestor for all women, known as Mitochondrial Eve, lived about 150,000 years ago. The common male-line ancestor for all men, Y-Chromosome Adam, lived about 60-90,000 years ago. This does not mean they are the ONLY ancestors – plenty of other people living at the same time as “Adam” and “Eve” have descendants surviving to the present day, but only “Adam” has descendants in the direct male line, just as “Eve” has descendants in the direct female line. In other words, the other woman alive at the same time as Eve have descendants, but their lines eventually produced only sons, leaving Eve’s mtDNA triumphant. Similarly, Adam was hardly the only man to produce sons, but the lines of other men ‘daughtered out’, breaking their Y-chromosome lines.

What they’re saying is that everyone alive 5000 years ago was either:

  1. your ancestor (via some line of descent), and that this is true whoever you are (an American, an African Bushman, an Australian Aborigine, whatever) or -

  2. not your ancestor, and not anyone else alive today’s ancestor either, because all their descendants died out.

In other words, they’re saying that nobody alive then is the ancestor of anyone aive now… unless they’re your ancestor as well.

I’ll show you my Chromosome if you’ll show me your Mitochondria.