Re: OT: births, was Re: Quick Announcement
| From: | John Cowan <cowan@...> |
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| Date: | Sunday, August 5, 2001, 1:50 |
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Matthew Kehrt scripsit:
> I find it amusing that my mother has managed to trace her family back to
> Charlemagne. This, doesn't mean anything of course; probably every
> European descendant in the world can do this.
Actually, it is very easy to show that everyone with European blood is either
descended from John the Miller (fl. 1296) or else John the Miller has no present
descendants at all.
The number of putative ancestors doubles in each ascending generation
(two parents, four grandparents, 8 great-grandparents, ...
2^(n+2) great^n-grandparents. Of course many of these are the same
persons, but let's suppose they aren't. With about 4 generations
per century, in 7 centuries one has 2^28 ancestors (more than 250
million), comfortably more than the population of Europe at that time.
Therefore, the probability that anyone who has present-day descendants is *not*
an ancestor is as close to zero as you like.
--
John Cowan cowan@ccil.org
One art/there is/no less/no more/All things/to do/with sparks/galore
--Douglas Hofstadter