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(+) Pedigree Collapse or We Are All Cousins

20 Jan 2023 3:49 PM | Anonymous

The following is a Plus Edition article written by and copyright by Dick Eastman. 

How many ancestors do you have? 

It is a simple question and would appear to have a simple answer: Any of us can count the number of our ancestors by performing a very obvious mathematical progression: two parents, four grandparents, eight great-grandparents, and so forth. In the past twenty generations, you have a mathematical chance of having more than one million ancestors. Thirty generations produces more than a billion ancestors, and forty generations results in more than one trillion.

The calculation is correct from a mathematical viewpoint but it ignores one obvious fact: there have never been that many humans on the face of the earth since the dawn of evolution! The reality is that it is impossible to have one trillion unique ancestors, regardless of the mathematics involved. 

In reality, we all have multiple lines of descent from single individuals. That is, if you could fill out a pedigree chart of all the names of all your ancestors going back forty generations, you would see the same individuals appearing time and time again in various places in the chart. For example, your mother's great-great-grandfather might be the same person as your father's great-great-great-grandfather, and so on and so forth, repeated thousands of times with different individuals at different places in your family tree. The further back you go in time, the more often certain individuals will appear in multiple locations in your ancestry.

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