Are we related? (maths questions)

[Ayahuasca]

1) Each person has four genetic grandparents.

2) So, going back 20 generations we each have 1,100,000,000,000 ancestors.

3) 20 generations is about 400 years.

4) The population of Britain in 1600 was 4,000,000.

So either:

1) My maths is all wrong, or

2) We are all related and you can all buy me a Christmas pressie!

?

[V8mate]

Ayahuasca said:

1) Each person has four genetic grandparents.

2) So, going back 20 generations we each have 1,100,000,000,000 ancestors.

Not in your case unfortunately. All of your sets of grandparents and their forebears were brother and sister.

[Ayahuasca]

V8mate said:

Ayahuasca said:

1) Each person has four genetic grandparents.

2) So, going back 20 generations we each have 1,100,000,000,000 ancestors.

Not in your case unfortunately. All of your sets of grandparents and their forebears were brother and sister.

You mistake me for someone from Norfolk.

[alock]

Ayahuasca said:

going back 20 generations we each have 1,100,000,000,000 ancestors.

I'd love to see your calculations for that.

Each generation going back has twice the number. Therefore the number in each generation is 2^(n-1) where n is the generation number. Your total number of ancestors (adding up all the generations) is therefore 2^n.

[Cock Womble]

If you're any good at maths then, no, we're not related.

[KingRichard]

alock said:

Ayahuasca said:

going back 20 generations we each have 1,100,000,000,000 ancestors.

I'd love to see your calculations for that.

Each generation going back has twice the number. Therefore the number in each generation is 2^(n-1) where n is the generation number. Your total number of ancestors (adding up all the generations) is therefore 2^n.

I'm crap at Algebra, what's the answer?

[Liszt]

KingRichard said:

alock said:

Ayahuasca said:

going back 20 generations we each have 1,100,000,000,000 ancestors.

I'd love to see your calculations for that.

Each generation going back has twice the number. Therefore the number in each generation is 2^(n-1) where n is the generation number. Your total number of ancestors (adding up all the generations) is therefore 2^n.

I'm crap at Algebra, what's the answer?

2^20 = 1048576

[V8mate]

Liszt said:

KingRichard said:

alock said:

Ayahuasca said:

going back 20 generations we each have 1,100,000,000,000 ancestors.

I'd love to see your calculations for that.

Each generation going back has twice the number. Therefore the number in each generation is 2^(n-1) where n is the generation number. Your total number of ancestors (adding up all the generations) is therefore 2^n.

I'm crap at Algebra, what's the answer?

2^20 = 1048576

Why is two the root? Why not four? (four grandparents)

[Liszt]

V8mate said:

Liszt said:

KingRichard said:

alock said:

Ayahuasca said:

going back 20 generations we each have 1,100,000,000,000 ancestors.

I'd love to see your calculations for that.

Each generation going back has twice the number. Therefore the number in each generation is 2^(n-1) where n is the generation number. Your total number of ancestors (adding up all the generations) is therefore 2^n.

I'm crap at Algebra, what's the answer?

2^20 = 1048576

Why is two the root? Why not four? (four grandparents)

How many parents did you have?

[V8mate]

Liszt said:

V8mate said:

Liszt said:

KingRichard said:

alock said:

Ayahuasca said:

going back 20 generations we each have 1,100,000,000,000 ancestors.

I'd love to see your calculations for that.

Each generation going back has twice the number. Therefore the number in each generation is 2^(n-1) where n is the generation number. Your total number of ancestors (adding up all the generations) is therefore 2^n.

I'm crap at Algebra, what's the answer?

2^20 = 1048576

Why is two the root? Why not four? (four grandparents)

How many parents did you have?

None.

Just the test tube.

[Dr Jekyll]

Two answers, both probably true.

1) There would have been a lot of 2nd/3rd cousins marrying in the old days simply because most people didn't move around much.

2) Everyone, at least in Western Europe, is probably related to each other.

I did see an estimate once that everyone has the emperor Augustus as an ancestor, but I don't know how they worked that out.

[V8mate]

Dr Jekyll said:

I did see an estimate once that everyone has the emperor Augustus as an ancestor, but I don't know how they worked that out.

Unless he was either the only male on the planet or already related to everyone at the time of his existence, it simply can't be true.

So it's not true

[shirt]

Ayahuasca said:

So either:

1) My maths is all wrong, or

2) We are all related and you can all buy me a Christmas pressie!

i'll go with 2. i bought you a nice bottle of scotch. send me the airfare and i'll bring it over brother.

[Dr Jekyll]

V8mate said:

Dr Jekyll said:

I did see an estimate once that everyone has the emperor Augustus as an ancestor, but I don't know how they worked that out.

Unless he was either the only male on the planet or already related to everyone at the time of his existence, it simply can't be true.

So it's not true

Unlikely, sure, but not intrinsically impossible. Certainly if you're just looking at Western Europe.

[Engineer1]

Bill Bryson's book a short history of nearly everything did the same maths, yes we are all related to each other in one way or another, the entire population of the earth has been scarily low at some points such as after the black death, during the Ice ages etc. Marrying your cousin was a normalish thing only a few generations back, and even fewer back if you are royalty .

[walm]

alock said:

Ayahuasca said:

going back 20 generations we each have 1,100,000,000,000 ancestors.

I'd love to see your calculations for that.

Each generation going back has twice the number. Therefore the number in each generation is 2^(n-1) where n is the generation number. Your total number of ancestors (adding up all the generations) is therefore 2^n.

You have defined ancestors as only direct parents and wikipedia agrees with you.

But perhaps, the OP was talking about being of common descent.
After all, the main point is to garner more Xmas pressies.
What about aunts, uncles, cousins, brothers, sisters? Some of them buy me presents.
Don't they count?