Human Family Tree Roots Are Shallow

[Sigrid]

I find the article linked below to be at odds with logic. Could someone (Egil, where are you?) who is scientific please comment on it as it seems drilled from top to botttom with multicultural wormholes:

An extract:

With the help of a statistician, a computer scientist and a supercomputer, Olson has calculated just how interconnected the human family tree is. You would have to go back in time only 2,000 to 5,000 years and probably on the low side of that range to find somebody who could count every person alive today as a descendant.

Furthermore, Olson and his colleagues have found that if you go back a little farther about 5,000 to 7,000 years ago everybody living today has exactly the same set of ancestors. In other words, every person who was alive at that time is either an ancestor to all 6 billion people living today, or their line died out and they have no remaining descendants.

The Source:

http://abcnews.go.com/Technology/wireStory?id=2142987

[Leofric]

It's a probabilities game, really, and it's largely based on mathematics.

Everyone has two parents, four grandparents, eight great grandparents, sixteen great great grandparents, and so on and so on.

That means that 1 generation back, a person has 2^1 ancestors.
2 generations back, it's 2^2.
3 back, it's 2^3.
4 back, it's 2^4.
And so on.

So on the nth generation back from you, you have 2^n ancestors.

Genealogists figure that generations average about 25 years. So 2000 years ago would be 80 generations.

On the 80th generation back, each of us has 2^80 ancestors, or 1,208,925,819,614,629,174,706,176 ancestors. The way we count in the US, that's 1.2 septillion ancestors on that generation alone.

Now obviously, no one has 1.2 septillion distinct ancestors who lived about 2000 years ago, since the population of the whole world was only about 200,000,000 (200 million we would say in the States) at that time. What we have are 1.2 septillion slots for ancestors on our pedigrees, with multiple slots getting filled by the same person due to inbreeding.

This is how that works. Suppose my father and my mother were actually brother and sister (they're not, but suppose). Then I would have four slots for grandparents, but only two people (my parents' parents) would fill those slots. If my grandparents were also brother and sister, then I'd have eight slots for great grandparents filled by just two people, each one getting listed four times.

Now if everyone who lived in the generation of about 2000 years ago were your ancestor, then each of them would fill an average of about 6,044,629,098,073,146 slots (that's about 6 quadrillion in US reckoning). So for any of the people living back then to not be represented in your pedigree at all would be pretty amazing from a probabilistic point of view.

However, since people don't mate randomly, but usually according to primarily geographical (and often ethnic or racial or religious or cultural) proximity, the chances of someone who's quite exotic being in your pedigree are rarer than raw probability would suggest. Even if everyone who lived back then were in your pedigree, they'd get much less representation than every person of your own kind. So say, the Pygmies might get 4,000 slots or so, but Europeans would get sextillions of slots.

Still, if Europeans got 1.199 septillion slots and left the rest of the world with only 0.001 septillion slots to split among themselves, you'd still have more than 99.9% of your ancestry being European while non-Europeans get 1 sextillion slots to split among themselves. No one would ever question your status as a full-blooded European and you could still be descended from everyone in the world at that time.

One thing that really makes this more possible is the tendency of royalty to marry outside their own ethnic group. As Zyklop has pointed out, almost everyone has royal ancestors. Royal ancestors would themselves have a great deal of ethnic/racial variety in their own pedigrees, passing that variety on down to everyone else, even though it be in extreme dilution.

Chances are very good that 4000 years back, everyone alive today would have had the exact same set of ancestors. However, they would have those in different combinations. There would be a lot of folks with very little representation on a given descendant's family tree and a few folks with a whole lot of representation on the tree, due to the general human practice of inbreeding.

I think the ramifications of this are not as earth-shattering, though, as some would have you believe. For the most part, it just confirms what we have already known for a long time.

First, it does not mean that everyone is black, everyone is white, everyone is yellow, everyone is red, and so forth. A certain kind still predominates for most people, and that kind defines them. An Icelander descended entirely from the original colonists is still an Icelander, even if somewhere back in the family tree, there was an Irishwoman who had been raped by a Roman soldier who had ancestors from as far away as Ethiopia. The Icelander in question is still overwhlemingly of Irish and Norwegian descent. The call of 99.9% of your blood probably trumps the call of the remaining 0.1%

Second, it does mean that it's silly to carry the idea of blood purity to extremes, whether you're talking about purity of royal lines or ethnic lines or whatever. Sure the Icelander in that example is descended from an Ethiopian. So is every other Icelander on earth, probably. There's no shame in it. It's not cause to question your heritage or celebrate Kwanzaa instead of Yule or anything else. The mixture isn't an impurity, since the concept of (im)purity of blood can only go back so far before it collapses.

Third, it does mean that ideas like "The children of Abraham are God's chosen people" don't really carry much weight. It's likely that everyone on earth is descended from Abraham — Jew, Arab, Gentile, or whatever. So the groups that claim to be God's chosen people because of descent from an ancient ancestor are also extending "God's chosen" status to everyone else as well.

Fourth, it also means that we should treat procreation with real respect. If every act of procreation can have such far-reaching consequences (just imagine the idea of all Icelanders being descended from, among other things, the rape of a single Irishwoman by a single Roman soldier), then it's something we ought to treat sacredly. And, in my opinion, it's something we ought to do a lot of — it never hurts to increase the chances of having everyone on earth 4000 years from now being descneded from you.

[Gorm the Old]

Well, Sigrid, I was going to reply to this, but Leofric beat me to the punch. I would have used exactly the same arguments which he did. They are fully valid (naturally). I've played this numbers game with many people many times and blown their minds. Usually, I'd carry the reasoning back 2000 years, assuming that every one of each person's 4 grandparents were different people and then, having come to the demonstrably absurd conclusion, ask "Alright, aside from the fact that all of the continents would be packed solidly with humanity from coast to coast, what's wrong here ?"

[Alizon Device]

I've talked to some American White Nationalists who claim, for instance, that the European Aryan is not descended from the same line that the negro is.
That we (or they) are somehow a different species!
As a one-time Biology and Chemistry undergrad, I find this preposterous, but the point is, it doesn't matter if human life started in Africa or wherever.

It's how we've evolved since then, since the migration to Europe, since our ancestors started breeding exclusively with only each other to create what we could call the White European.
And if the time scale is much shorter than previously thought, we've done even better than we thought.