I have 2 parents, (had) 4 grandparents, 8 great-grandparents, 16 great- great grand parents etc. If every generation lasts approx 40 years then 400 years ago about 2 to the power 10 (1,024) people were alive who were my ancestors. Follow me so far?
2000 years ago, is about 40 generations ago. So 2 to the power 40 people must have been alive who were my ancestors. That's about 1million, million people. (one billion in the US, 1000 million in the UK).
But there simply weren't that many people on the earth at that time. So was everyone alive 2000 years ago my ancestor?
2006-08-08 04:24:34 · 10 answers · asked by garden sunbather 1 in Science & Mathematics ➔ Mathematics
Nope. Imagine an island with just 100 people on it, 50 men, 50 women. They all have two children. That means 100 children, not 200. The adults stop having children, the kids grow up and marry each other and each have - two children. The first generation dies. The process continues. After a while people are marrying their first cousins, which is what happened in many sparsely settled counties in the US before 1900. At any given time there will be no more than 300 people on the island - 100 grandparents, 100 parents and 100 children, not 2 to some power.
If you are Jewish, there is a chance Jesus is your 1st, 2nd, 3rd, 4th . . . cousin, 60 times removed. If you have English, French, German, Swiss, Northern Italian or BeNeLux roots, there is a 70% chance you are related to Charlemagne.
2006-08-09 11:48:53 · answer #1 · answered by Anonymous · 2⤊ 0⤋
Your logic is flawed. You have at most 2^n, nth degree parents
(i.e., 1 is parents 2 is grand and so on)
The reality is that some of these could be the same. In fact some may appear even in different degrees.
So 2^n is an UPPER BOUND not the actual number of ancestors
Secondly genetic lines died out. Some people dont have kids. Even 2000 years ago there are people who didnt have kids. Thus they couldnt be your direct ancestor. And again your logic falls apart.
Thirdly, jesus didnt have kids. Well this is a matter of debate but the first two prove your statement wrong.
2006-08-08 14:21:07 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Good question. Tennessee comments aside, if some of your cousins married each other this would severely cut into the exponential growth. As a (rather severe) counterexample, suppose that you are the product of 40 generations of brother-sister inbreeding. Then you should have a minimum of 80 ancestors. The number gets even lower if the incest is intergenerational.
2006-08-08 11:39:13 · answer #3 · answered by Benjamin N 4 · 0⤊ 0⤋
No. As the travel between differnet continents and areas was a lot less restrictive, they weren't. Many of these people will be common ancesters of other ancestors - for example, they may have shared the same great grandparents. A lot of inter breeding has occured in humanity's history.
Due to genteic change and drift, it doesn't matter who your ancestors were back then anyway, really.
2006-08-08 11:33:58 · answer #4 · answered by Mudkips 4 · 0⤊ 0⤋
N generations ago, 25*N years ago, you had 2^N great-...-grandparents is the proven formula. Given that the above used 40 verses the 25 years of age as average reproduction age. The above person is within limits correct. If you doubt see the inventor of the formula and his noted, http://mathforum.org/library/drmath/view/55586.html
2014-02-27 08:16:08 · answer #5 · answered by Brett 1 · 0⤊ 0⤋
It's tempting to say that it depends on how much your Mother got around, but I'll resist the urge
Fact is, pretty much everyone on the planet is related to everyone else
OTOH, Jesus was an only child and he (according to legend) had no children. That kinda lets him out as being a direct ancestor. OTOH one of his Grandfathers (or Grandmothers) might be a direct ancestor of yours which would make him a cousin (a *bunch* of times removed)
Doug
2006-08-08 11:36:46 · answer #6 · answered by doug_donaghue 7 · 1⤊ 0⤋
The flaw in your argument is that one person can occur in several branches of your family tree. Especially if your ancestors lived in a small village, or in Tennessee.
2006-08-08 11:29:12 · answer #7 · answered by Anonymous · 0⤊ 0⤋
Most of your ancestors would have been (distantly) related, just by fact of them living in the same place. Cuts the figure down hugely.
2006-08-08 11:29:44 · answer #8 · answered by Oracle Of Delphi 4 · 0⤊ 0⤋
you have got the billions mixed up it's a thousand million in the uk and the Us
2006-08-08 11:29:40 · answer #9 · answered by Anonymous · 0⤊ 0⤋
i don't know.... my family go back to 1023AD... and some were at the Battle of Hastings ( 1066 )...Plus i have "Land title" & a Coat of Arms....
2006-08-08 11:39:25 · answer #10 · answered by Anonymous · 0⤊ 0⤋