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HalfMooner
Dingaling

Philippines
15831 Posts

Posted - 07/03/2006 :  16:24:51  Show Profile Send HalfMooner a Private Message
Please use the "common ancestor" link halfway down this page at the Archaeology Magazine Web site to see the original article. Sorry, I couldn't make the direct link work here.
quote:
Roots of human family tree are shallow

By MATT CRENSON, AP National Writer Sat Jul 1, 5:17 PM ET

Whoever it was probably lived a few thousand years ago, somewhere in East Asia Taiwan, Malaysia and Siberia all are likely locations. He or she did nothing more remarkable than be born, live, have children and die.

Yet this was the ancestor of every person now living on Earth the last person in history whose family tree branches out to touch all 6.5 billion people on the planet today.

That means everybody on Earth descends from somebody who was around as recently as the reign of Tutankhamen, maybe even during the Golden Age of ancient Greece. There's even a chance that our last shared ancestor lived at the time of Christ.

"It's a mathematical certainty that that person existed," said Steve Olson, whose 2002 book "Mapping Human History" traces the history of the species since its origins in Africa more than 100,000 years ago.

It is human nature to wonder about our ancestors who they were, where they lived, what they were like. People trace their genealogy, collect antiques and visit historical sites hoping to capture just a glimpse of those who came before, to locate themselves in the sweep of history and position themselves in the web of human existence.

But few people realize just how intricately that web connects them not just to people living on the planet today, but to everyone who ever lived.

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.

That revelation is "especially startling," statistician Jotun Hein of England's Oxford University wrote in a commentary on the research published by the journal Nature.

"Had you entered any village on Earth in around 3,000 B.C., the first person you would have met would probably be your ancestor," Hein marveled.

It also means that all of us have ancestors of every color and creed. Every Palestinian suicide bomber has Jews in his past. Every Sunni Muslim in Iraq is descended from at least one Shiite. And every Klansman's family has African roots.

How can this be?

It's simple math. Every person has two parents, four grandparents and eight great-grandparents. Keep doubling back through the generations 16, 32, 64, 128 and within a few hundred years you have thousands of ancestors.

It's nothing more than exponential growth combined with the facts of life. By the 15th century you've got a million ancestors. By the 13th you've got a billion. Sometime around the 9th century just 40 generations ago the number tops a trillion.

But wait. How could anybody much less everybody alive today have had a trillion ancestors living during the 9th century?

The answer is, they didn't. Imagine there was a man living 1,200 years ago whose daughter was your mother's 36th great-grandmother, and whose son was your father's 36th great-grandfather. That would put him on two branches on your family tree, one on your mother's side and one on your father's.

In fact, most of the people who lived 1,200 years ago appear not twice, but thousands of times on our family trees, because there were only 200 million people on Earth back then. Simple division a trillion divided by 200 million shows that on average each person back then would appear 5,000 times on the family tree of every single individual living today.

But things are never average. Many of the people who were alive in the year 800 never had children; they don't appear on anybody's family tree. Meanwhile, more prolific members of society would show up many more than 5,000 times on a lot of people's trees.

Keep going back in time, and there are fewer and fewer people available to put on more and more branches of the 6.5 billion family trees of people living today. It is mathematically inevitable that at some point, there will be a person who appears at least once on everybody's tree.

But don't stop there; keep going back. As the number of potential ancestors dwindles and the number of branches explodes there comes a time when every single person on Earth is an ancestor to all of us, except the ones who never had children or whose lines eventually died out.

And it wasn't all that long ago. When you walk through an exhibit of Ancient Egyptian art from the time of the pyramids, everything there was very likely created by one of your ancestors every statue, every hieroglyph, every gold necklace. If there is a mummy lying in the center of the room, that person was almost certainly your ancestor, too.

It means when Muslims, Jews or Christians claim to be children of Abraham, they are all bound to be right.

. . .


Creationists will doubtless seek to twist this fascinating work, to support a Biblical human creation circa 6000 years ago.



Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive.

McQ
Skeptic Friend

USA
258 Posts

Posted - 07/03/2006 :  19:43:39   [Permalink]  Show Profile Send McQ a Private Message
Yeah, but what if you're Shirley MacLaine? She must actually BE thousands of her own ancestors! LOL!

Great find, HalfMooner!

Elvis didn't do no drugs!
--Penn Gillette
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Zebra
Skeptic Friend

USA
354 Posts

Posted - 07/03/2006 :  23:01:02   [Permalink]  Show Profile Send Zebra a Private Message
Interesting. Mathematically it seems like it makes sense, but it's hard to picture people looking so different, and living so many different places, yet being so inter-related.

Here's a direct link to the story

And, I'm not sure if there's a particular reason the article was just released - maybe they've just published a more updated paper with their results? Because here's an NPR interview from September 2004 by Robert Siegel with one of the researchers, with the same general gist, after they'd had an article published in Nature. The NPR interview includes the extra tidbit that the only exception they found were native Tasmanians, who probably were isolated as of 8000-9000 years ago.

Last year, I scrounged around online & found a bunch of info for a genealogy of my father's line. Between 1638 and 1720 he had at least 40 direct forebears who lived in Rhode Island. I found one couple, married by 1640, whose great-times-5-grandson (through one of their daughters, Mary) married their great-times-4-granddaughter (through one of their sons), in ~1840. (One of the kids from that ~1840 marriage was my great-grandmother.)

Not only that, but the son-in-law of the ~1640 couple married again after his wife Mary (mentioned above) died; his second wife already had some children & through them ended up being the great-grandmother (father's grandmother) of a woman whose other great-grandparents (mother's grandparents) were that very same 1640 couple. Without any incest, at least none that showed up in the official records.

Well, it's hard to picture the interconnections when it's written out like this, but on the genealogy I did it's cool to see the number of people double in each generation - then contract a bit in the mid 1600's, when this ~1640 couple comes into the mix.

I think, you know, freedom means freedom for everyone* -Dick Cheney

*some restrictions may apply
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BigPapaSmurf
SFN Die Hard

3192 Posts

Posted - 07/04/2006 :  12:10:13   [Permalink]  Show Profile Send BigPapaSmurf a Private Message
This is a joke, many populations have been more or less isolated from other groups long enough so where mr. miracles offspring wouldnt have made it into the fold.

Looks like a math trick to me.

Is there any genetic data to back this BS up? Or just multiplication tricks?

"...things I have neither seen nor experienced nor heard tell of from anybody else; things, what is more, that do not in fact exist and could not ever exist at all. So my readers must not believe a word I say." -Lucian on his book True History

"...They accept such things on faith alone, without any evidence. So if a fraudulent and cunning person who knows how to take advantage of a situation comes among them, he can make himself rich in a short time." -Lucian critical of early Christians c.166 AD From his book, De Morte Peregrini
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beskeptigal
SFN Die Hard

USA
3834 Posts

Posted - 07/04/2006 :  12:37:50   [Permalink]  Show Profile Send beskeptigal a Private Message
I don't buy this. For example Aboriginals in Australia left Africa 40-60,000 years ago. How could they have an ancestor in common from only 6,000 years ago? So these people have no pure descendants left? Is that the idea?

I can't see that we've all mixed that much in the last few millenniums. I understand the statistical premise but it doesn't account for isolation of groups.
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HalfMooner
Dingaling

Philippines
15831 Posts

Posted - 07/04/2006 :  13:44:45   [Permalink]  Show Profile Send HalfMooner a Private Message
quote:
Originally posted by beskeptigal

I don't buy this. For example Aboriginals in Australia left Africa 40-60,000 years ago. How could they have an ancestor in common from only 6,000 years ago? So these people have no pure descendants left? Is that the idea?

I can't see that we've all mixed that much in the last few millenniums. I understand the statistical premise but it doesn't account for isolation of groups.

I suppose the point of the study is showing mathematically that everyone is recently related. Problem is, this is based on math alone, not other evidence. My problem with the Aboriginals fitting ito this study is that they had been largely in isolation for tens of thousands of years, with only a little probable contact by their northern-most population with sea traders such as the Chinese and Indonesians in recent millennia. Though the Aborigines may not have been completely isolated genetically, they must have been nearly so for tens of thousands of years.

There must have been other peoples who were equally, or even more, isolated, perhaps including the Fuegians, various arctic peoples, and some of the peoples living in mountainous areas of the south-east Asian islands. Essentially, this study seems to be interesting, and points out the general fact of human interrelatedness, but without supporting evidence of any kind, its conclusions should be taken very cautiously.


Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive.
Edited by - HalfMooner on 07/04/2006 13:47:37
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Dave W.
Info Junkie

USA
26009 Posts

Posted - 07/04/2006 :  15:51:47   [Permalink]  Show Profile  Visit Dave W.'s Homepage Send Dave W. a Private Message
Well, we know already from the poorly named "Mitochondrial Eve" studies that all living humans today are related through a single woman. The difference between the current research and the "ME" research is that the "ME" lived some 80,000 years ago, a much more credible figure given isolationist peoples around the world. I mean, the idea that our last common ancestor might have existed only 2,000 years ago is based on the premise that as soon as "contact" between some small tribe and the rest of the world, the tribespeople almost instantly are swapping European genes like rabbits. I would find that hard to believe. I would find it hard to believe that there do not exist any native Americans who've avoided European genes.

- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
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JohnOAS
SFN Regular

Australia
800 Posts

Posted - 07/04/2006 :  17:41:34   [Permalink]  Show Profile  Visit JohnOAS's Homepage Send JohnOAS a Private Message
quote:
Originally posted by Dave W.

Well, we know already from the poorly named "Mitochondrial Eve" studies that all living humans today are related through a single woman. The difference between the current research and the "ME" research is that the "ME" lived some 80,000 years ago, a much more credible figure given isolationist peoples around the world. I mean, the idea that our last common ancestor might have existed only 2,000 years ago is based on the premise that as soon as "contact" between some small tribe and the rest of the world, the tribespeople almost instantly are swapping European genes like rabbits. I would find that hard to believe. I would find it hard to believe that there do not exist any native Americans who've avoided European genes.


Yup, the fact that if you go back far enough we all have a common ancestor is as close to a fact as we're likely to need. The maths in the article posted by HalfMooner is simply flawed in a few assumptions and the attached calculations. I can imagine the YEC crowd claiming that evolution supports their stance any moment now. It's also worth that "Mitochondrial Eve" (ME) is a shifting title, and that there would have been a different ME at the time our ME was alive.

The first good explaination I remember reading of this was in Richard Dawkins "The Ancestor's Tale: A Pilgrimage to the Dawn of Evolution" (link here), which is a quite interesting reverse chronology of human ancestry.

John's just this guy, you know.
Edited by - JohnOAS on 07/04/2006 17:47:40
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beskeptigal
SFN Die Hard

USA
3834 Posts

Posted - 07/05/2006 :  01:05:33   [Permalink]  Show Profile Send beskeptigal a Private Message
quote:
Originally posted by Dave W.

Well, we know already from the poorly named "Mitochondrial Eve" studies that all living humans today are related through a single woman. The difference between the current research and the "ME" research is that the "ME" lived some 80,000 years ago, a much more credible figure given isolationist peoples around the world. I mean, the idea that our last common ancestor might have existed only 2,000 years ago is based on the premise that as soon as "contact" between some small tribe and the rest of the world, the tribespeople almost instantly are swapping European genes like rabbits. I would find that hard to believe. I would find it hard to believe that there do not exist any native Americans who've avoided European genes.

Not only was ME much further back than 6K years, there was a bottleneck ~60,000 years ago that the human population dwindled to as few as 1,000 members. But humans existed before that.
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beskeptigal
SFN Die Hard

USA
3834 Posts

Posted - 07/05/2006 :  01:08:09   [Permalink]  Show Profile Send beskeptigal a Private Message
This looks like some detailed work on the original specific lineages.
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Dr. Mabuse
Septic Fiend

Sweden
9677 Posts

Posted - 07/05/2006 :  06:39:08   [Permalink]  Show Profile  Send Dr. Mabuse an ICQ Message Send Dr. Mabuse a Private Message
quote:
Originally posted by Zebra

Interesting. Mathematically it seems like it makes sense, but it's hard to picture people looking so different, and living so many different places, yet being so inter-related.

I don't find it that unfathomable. Just take a look at all the dog-breeds. A few thousand years ago the ancestors all breeds, from Chow-Chow and Pekinese to New Foundland and Grand Danois, didn't look much different from wolves.

Dr. Mabuse - "When the going gets tough, the tough get Duct-tape..."
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"Equivocation is not just a job, for a creationist it's a way of life..." Dr. Mabuse

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HalfMooner
Dingaling

Philippines
15831 Posts

Posted - 07/05/2006 :  14:02:31   [Permalink]  Show Profile Send HalfMooner a Private Message
Dr. Mab hit on the other family tree that fascinates me, that of the dogs. I think this line of descent parallels ours for a good long distance, but very little if any, paleontological work has deliberately been done on the dog -- most of the scant early dog (or maybe wolf) finds come accidentally from work focused on humans.

Thanks, JohnOAS and beskeptigal, for the links! On the subject of the spread and lineages if early humans, here's another link that I like, if only for the usual Nat Geo quality of the presentation.


Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive.
Edited by - HalfMooner on 07/05/2006 15:19:26
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Zebra
Skeptic Friend

USA
354 Posts

Posted - 07/05/2006 :  20:34:50   [Permalink]  Show Profile Send Zebra a Private Message
I looked at this group's 2004 paper in Nature from work earlier today (found out this evening I can't access it from home) - they tried their estimate with several different conditions & got surprisingly recent results each time, within a range of a few millenia. Of course, any truly isolated population clearly would push the latest date for a "most recent common ancestor" (MRCA) for everyone on earth back to that group's last "reproductive contact" with another, less isolated population.

This Wikipedia section within the page on MRCA addresses some of the concerns people have raised in discussion here:
quote:
Depending on the survival of isolated lineages without admixture from Modern migrations and taking into account long-isolated peoples, such as historical tribes in central Africa, Australia and remote islands in the South Pacific, the human MRCA is generally assumed to have lived in the Paleolithic period.

However, Rohde, Olson, and Chang (2004), using a non-genetic model, estimated that the MRCA of all living humans may have lived within historical times (3rd millennium BC to 1st millennium AD). Rohde (2005) refined the simulation with parameters from estimated historical human migrations and of population densities. For conservative parameters, he pushes back the date for the MRCA to the 6th millennium BC (p. 20), but still concludes with a "surprisingly recent" estimate of a MRCA living in the second or first millennium BC (p. 27). An explanation of this result is that, while humanity's MRCA was indeed a Paleolithic individual up to Early Modern times, the European explorers of the 16th and 17th centuries would have fathered enough offspring so that some "mainland" ancestry by today pervades even remote habitats. The possibility remains, however, that a single isolated population with no recent "mainland" admixture persists somewhere, which would immediately push back the date of humanity's MRCA by many millennia. While simulations help estimate probabilities, the question can only be resolved authoritatively by genetically testing every living human individual.

Other models reported in Rohde, Olson, and Chang (2004) suggest that the MRCA of Western Europeans lived as recently as AD 1000. The same article provides surprisingly recent estimates for the identical ancestors point, the most recent time when each person then living was either an ancestor of all the persons alive today or an ancestor of none of them. The estimates for this are similarly uncertain, but date to considerably earlier than the MRCA, according to Rohde (2005) roughly to between 15,000 and 5,000 years ago.
Clearly, the closer culturally and geographically a selected collection of people is, the more recent their MRCA will be, since those factors correlate with higher likelihood of past reproductive pairing, ie shared ancestors.

For those who want to do a quick-and-dirty calculation to see what the math might offer, try this. Imagine you're looking at the genealogy of any one person alive today. Call the generation number n, using n=0 for the proband (the person we're talking about), adding one for each generation before that (so n=1 for the parents, n=2 for the grandparents, and so on). Then, the number of people in any given generation of the genealogy chart equals 2^n (2 to the n power), with 2^0=1 for the proband, 2^1=2 for his parents, 2^2=4 for the grandparents, and so on.

If one generation is 50 years, from birth to reproduction that's the upper limit for women - then 2000 years is 40 generations. (Twenty to 30 years is probably more realistic. If a generation is shorter than 50 years, then there are more generations in 2000 years.

I think, you know, freedom means freedom for everyone* -Dick Cheney

*some restrictions may apply
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HalfMooner
Dingaling

Philippines
15831 Posts

Posted - 07/05/2006 :  22:14:24   [Permalink]  Show Profile Send HalfMooner a Private Message
Math hard. Brain hurts. Can I go home now?


Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive.
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woolytoad
Skeptic Friend

313 Posts

Posted - 07/06/2006 :  00:08:04   [Permalink]  Show Profile Send woolytoad a Private Message
quote:
Originally posted by JohnOAS

[quote]The maths in the article posted by HalfMooner is simply flawed in a few assumptions and the attached calculations. I can imagine the YEC crowd claiming that evolution supports their stance any moment now. It's also worth that "Mitochondrial Eve" (ME) is a shifting title, and that there would have been a different ME at the time our ME was alive.



The assumptions are not so flawed. If we consider only continents that are relatively close together, the assumptions are quite OK. It would have been easy for each population to come into contact with each other. And the math is correct even if it is simplistic. Of course isolated groups will push the date back.

I reckon it would be far more interesting if there were large unrelated populations of people.
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Zebra
Skeptic Friend

USA
354 Posts

Posted - 07/06/2006 :  00:38:30   [Permalink]  Show Profile Send Zebra a Private Message
quote:
Originally posted by HalfMooner

Math hard. Brain hurts. Can I go home now?



No. Must study. Test tomorrow. Bring #2 pencil.

I think, you know, freedom means freedom for everyone* -Dick Cheney

*some restrictions may apply
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