too many poeple?

Question

I have 2 parents, each of them has 2 parents and each of them has 2 parents etc etc. If i were to draw a family tree back from me and go back 30 generations (only 1000 years) the top line would have over 1 billion ansestors. and the total number of poeple in this tree would have more poeple than ever lived. This off course is not possible, where is the maths gone wrong?

Answer 1

Count your own parents as the 1st generation: thats 2 persons.
2nd generation=2^2 persons
3rd generation=2^3 persons
.....
30th generation = 2^30 persons

Note: You are counted as part of the tree.

Total number of people in all = 1 + 2 + 4 + 8 + ...+ 1073741824.
= 2147483647

This number is achievable if your generation continues to exist (all things being equal), no break in the family tree. It'll take many, many years! So Maths has not gone wrong.

Answer 2

Are just using 2^30?

For 30 generations, it should be more 2*30

Answer 3

Not so much incest as closer relations marrying. Not much more than 100 years ago, few people travelled more than a few miles from their homes. If you were to trace back your family tree, you would be surprised at the number of famous people you were related to.

Answer 4

you are assuming than none of your parents ancestors are overlaping. going back 30 generations it is very likely that somewhere your mothers side and your fathers side intersect.

Answer 5

You have not accounted for incest or more accurately inbreeding (procreation between individuals with varying degrees of genetic closeness)...

Answer 6

That's a lot of leafs on the tree.

: )

Answer 7

multiple matings would put an interesting spin on this question.

Answer 8

My head just exploded!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Answer 9

incest.