Everyone is Descended From Charlemagne

Darrin Ritter darrinritter at optusnet.com.au
Thu Aug 17 22:33:15 CST 2006


all UNIX descends in some way from the original code by Ken Thompson


On Thu, 2006-08-17 at 12:35 -0700, James Leone wrote:
> In the last few months I have been doing tons of
> genealogical work over at www.ancestry.com. I started
> to find some records that went so far back that I
> started to find them unbelievable, so I poked around
> to see if anyone else had similar felings. Then I
> found the web page below, and thought that it would be
> fun to bring it up with the well educated folk here at
> Linuxsa. 
> 
> What do you think, is his analysis correct or is this
> a hoax? 
> 
> I'm almost convinced that given the numbers, we all
> cousins....
> 
> [1]Freebsd
> 
> From:
> http://www.oz.net/~lee/Genealogy/charlemagne.html
> 
> > As I was researching my Lee ancestral line back into
> > the middle ages, I was excited to find that I am 
> > apparently a direct descendant of Charlemagne, the 
> > first Holy Roman Emperor. As I dug deeper, I found 
> > at least three separate lines of descent from him to
> > me, and I saw more and more genealogical sites on 
> > the Web that claimed similar descent. This started 
> > me thinking about how likely it is that I, or anyone
> > for that matter, might be descended from a 
> > particular person that far back. As a mathematician
> > (though not by any means a probabilist), I figured I
> > ought to be able to come up with at least a rough 
> > estimate of the probability. My conclusion, which 
> > was surprising (to me at least), is that
> 
> > there is virtually no chance that anyone of European
> > ancestry is not directly descended from Charlemagne.
> 
> > Here's my reasoning. Charlemagne was approximately 
> > 40 generations back from the present day. Each 
> > person has 2 parents, 22 = 4 grandparents, 23 = 8 
> > great-grandparents, ... and 240, or approximately 
> > 1,000,000,000,000 (one trillion), 40th-generation 
> > ancestors, which means half a trillion male 
> > ancestors. Of course, since the entire male 
> > population of Europe at the time of Charlemagne was
> > only about 15 million, these half trillion ancestors
> > cannot all have been different men -- obviously 
> > there has been a lot of cross-breeding, and many of
> > our ancestral lines cross and re-cross, eventually 
> > ending up at the same person. Let's assume that each
> > of my 40th-generation male ancestors is a randomly-
> > chosen man from eighth-century Europe (this is not 
> > really valid, but more on that below). Choosing any
> > one such ancestor, say my father's father's ... 
> > father's father, the probability that that 
> > particular person is Charlemagne is one in 15 
> > million. Pretty small. To put it another way, the 
> > probability that any particular ancestor was not 
> > Charlemagne is 1 - 1/15,000,000, or approximately 
> > 0.999999933
> 
> > But now consider the probability that none of my 
> > 40th-generation ancestors is Charlemagne. For that 
> > to happen, every one of my half trillion male 
> > ancestors has to not be Charlemagne, which would be
> > an amazing coincidence. To see how amazing, let's 
> > compute the probability. Assuming all of these 
> > various not-being-Charlemagne occurrences are 
> > independent of each other (more on this below), the
> > laws of probability state that the probability of 
> > all these events occurring simultaneously is 
> > obtained by multiplying together their individual 
> > probabilities:
> 
> >(0.999999933)·(0.999999933)·...·(0.999999933) = 
> >(0.999999933)500,000,000,000.
> 
> > This turns out to be an incredibly small number: 
> > about one chance in 1015,000. That's a one with 
> > 15,000 zeroes after it, a number that's too big even
> > to display in a browser window. This is way more 
> > than the number of atoms in the universe (which is 
> > estimated to be about 1080). Therefore, if this 
> > analysis is even remotely close to correct, it's 
> > virtually impossible that Charlemagne is not among 
> > my direct ancestors.
> 
> > Of course, there are a few sources of errors in this
> > analysis, so there are various corrections one could
> > make that might yield a more accurate estimate. Most
> > obviously, one's ancestors are not in fact randomly
> > chosen people from eighth-century Europe. For 
> > example, anyone who had no children, or no 
> > grandchildren, cannot be an ancestor of someone 
> > living now. (Charlemagne has well-documented 
> > descendants down to the present day.) More 
> > generally, wealthy people survived at a far higher 
> > rate than the rest of the population, and so were 
> > much more likely to produce descendants - thus one's
> > ancestors are more likely to be found among the 
> > relatively small population of royalty and nobility,
> > including Charlemagne. You might think of other, 
> > smaller, corrections, such as the fact that the 
> > probabilities of different ancestors being 
> > Charlemagne are not really independent: for example,
> > if my father's ... father's father was Charlemagne's
> > brother, then the probability that my father's ... 
> > mother's father was Charlemagne himself is very 
> > small. And, of course, some of my ancestors came 
> > from outside of Europe. But I believe these effects
> > cannot change the fact that the probability we're 
> > talking about is so tiny as to be zero for all 
> > practical purposes.
> > --Jack Lee
> 
> James "Cousin Yank" Leone
> 
> [1] Beer
> 
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