Where are all these ancestors ?

Question:

Where are all these ancestors ?

I have 2 parents, 4 grandparents, 8 great grandparents etc. You get the picture. I worked out that if you go back 50 generations (in other words to the time of the first Anglo Saxon settlers in the British Isles) I should be able to pick out trillions and trilions of ancestors. Just try doubling the number 50 times, Excel can't even display the number.
But there weren't that many people in the world at that time, so... what happened to all my ancestors ??

Best Answer - Chosen by Asker: Hey Gav,

Good question - the powers of two are overwhelming. If you go back 50 generations, you would be descendant from more people than there are on earth. How can that be? Well, your tree collapses many many many times. 3rd cousin marriages, etc will divide it by two. This happens so often, we don't recognize it.