If You have 2 parents, 4 grandparents, 8 great parents, so if you go back 40 generations you’d have a supposed 1 Trillion ancestors, But only 100B humans have ever existed. Explain.
In: Biology
everyone is related to some degree. people have lots of kids with lots of different people, so there’s more overlapping than you would think in family trees all over the world.
I think that you have to consider how many years ago 40 generations would really be. There is a possibility that going back that far may not be possible as it may predate humans. Just for an example, I was born in 1980, my mom was born in 1961, my grandfather was born in 1933, my Great Grandfather was born in 1887, my Great Great grandfather was born in 1853, and my Great Great Great Grandfather was born in 1822. So 6 generations from a single line takes us back 200 years. Depending on age at the time of giving birth you could go back further with less generations. I’ve got genealogy that traces one line of my family back to the early 1300’s, and that’s only about 10-15 generations from me. It would be interesting to see if someone could trace back 40 generations and see what years those ancestors were born.
Basically, the same person represents multiple branches in the ancestral tree. This is called pedigree collapse. That also tells us that people who were alive a few thousand years ago are either the ancestor of almost everyone alive today, or no one.
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