Pedigree Collapse
How many unique ancestors do you have?
We all have two parents, four grandparents, eight great-grandparents, 16 great-great-grandparents and so on, right? If this were true, by the 40th generation back, about 1,000 years ago, we each should have 2,199,023,255,550 unique ancestors. (See chart below.)
But only about 117 billion people have been born in all of history.
To marry someone, you first have to meet them. For most of history, people lived in small communities. Many had to walk wherever they wanted to go. That means they usually would marry someone living within five miles of their homes.
It’s estimated that since the beginning of humanity, 80% of people married their first or second cousins. In Madge’s tree, this happened a number of times. This cuts down considerably on the number of unique ancestors Madge and we had.
The official term is “pedigree collapse.” If you’d like to learn more, here are some articles.
