Humanity's Common Ancestor Only ~3500 Years Old

[Dauphin]

Originally posted by MikeH


That's not what it says. It says we all share 1 common ancestor which means that out of the several million people in everyones family tree going back 3,500 years there is likely to be one person who appears in all of them.

This is a hard concept to understand possibly if you don't know much about statistics but I think it's quite possible.

Let's look at the maths.

Say one person has 2 children who survive to reproduve and their children have 2 children each who survive to reproduce, and so on for 3,500 years.

Take the age of a generation as 25 (only in the last 100 years has it got much bigger).

3500/25 = 140

So there have been 140 generations. If we assume that each offspring has 2 children who survive to reproduce then by the year 2000 the descendents of that person would number 2^140 (2*2*2... 140 times).

That gives you

1.4*10^42 descendents
In other words one person whos family had reproduced 2 children every generation would have descendents numbering 2*10^32 times more people than the current population of the earth.

Even if you reduced it to an average of 1.5 surviving children or something the numbers are vastly bigger than the population of the planet. It's actually not just possible but it'd be amazing if most of us didn't share one or two ancestors.

What that analysis demonstrates categorically is that we (as individuals) are descended from given ancestors through multiple lineages.

What it says about freely mixing groups is compelling.

What is says about seperated groups is little. Needs more data.

[lord of the mark]

Originally posted by GePap


Thats not what the model says-the model is not saying there was one common ancestor 3500 years ago- its saying you would have at least one common ancestor with every human being living on the planet if you and them searched your family trees far enough back, and that by the time you reached 1500 BC you would have found one common ancestor with everyone else.

How would this work with the Americas?

Well, first, most Native American populations were killed off. So talking about the remants, the idea is that along the line, in the heritage of any of them, somebody walked in who was the decendent of someone born who had one parent from Eurasia-perhaps some native woman raped by a European, or a Zambo (slave mixed with Indian), or a meztizo, whatever.

Does the theory apply to the Americas based on the European encounter, or on post 3500 BCE (inuit) migration? or perhaps on no historical specifics, but simply some impedence factor for migrations? hard to say without seeing the article.

[GePap]

It mentions current populations, I would assume we are not talking about the Innuit migration-after all, the vast majority of people in the new world can pretty clearly trace their lineage back to someone who lived after 1492.

[lord of the mark]

Originally posted by GePap
It mentions current populations, I would assume we are not talking about the Innuit migration-after all, the vast majority of people in the new world can pretty clearly trace their lineage back to someone who lived after 1492.

yes,well. I thing everyone alive today can trace their ancestry back to someone who live after 1492.

Clearly there was a large migration of europeans (and asians and africans) to the new world after 1492. I think when people express surprise that the model holds for the new world they are speaking of the "aboriginal" population of the new world. Now it MAY be that that is a false concept, that EVERY single person claiming to be a "native american" from Canada to Argentina has some ancestry among europeans, asians or africans who migrated post-1492. Its NOT clear to me that the original article claims that.

the other alternative is that it refers, as some have said, to post land-bridge migration from northeast asia via the circumpolar region. We know such migration DID take place - it gave rise to the inuit peoples. Its not clear to me if southward migration/intermarriage could mean that all native peoples had a post-3500 BCE old world ancestor PRIOR to 1492 CE.

[GePap]

the other alternative is that it refers, as some have said, to post land-bridge migration from northeast asia via the circumpolar region. We know such migration DID take place - it gave rise to the inuit peoples. Its not clear to me if southward migration/intermarriage could mean that all native peoples had a post-3500 BCE old world ancestor PRIOR to 1492 CE.

Highly unlikely-specially since were are talking about 1500BCE, NOT 3500BCE (the article says 3500 years ago, given).

The article also mentions only living populations. Given that disease wiped out 90% or so of the pre-columbian population we really would have no clue.

[lord of the mark]

Originally posted by GePap

the other alternative is that it refers, as some have said, to post land-bridge migration from northeast asia via the circumpolar region. We know such migration DID take place - it gave rise to the inuit peoples. Its not clear to me if southward migration/intermarriage could mean that all native peoples had a post-3500 BCE old world ancestor PRIOR to 1492 CE.

Highly unlikely-specially since were are talking about 1500BCE, NOT 3500BCE (the article says 3500 years ago, given).

The article also mentions only living populations. Given that disease wiped out 90% or so of the pre-columbian population we really would have no clue.

1500 BCE - my bad.
Im not sure when there ceased to be migration from circumpolar asia to the North American Inuit.



living populations - they refer to all individuals alive today. Presumably this includes the descendants of the pre-Columbian population of the Americas. Of whom id have thought at least a few have no ancestors among the post 1492 migrants to the Americas. I could well be wrong, but that strikes me as highly surprising, given the existence, esp in North America, of some very distinctive of native life, with large areas having no european contact until well into the 19th cent, and with the limited time for the process to take place since then.

[GePap]

Originally posted by lord of the mark



1500 BCE - my bad.
Im not sure when there ceased to be migration from circumpolar asia to the North American Inuit.



living populations - they refer to all individuals alive today. Presumably this includes the descendants of the pre-Columbian population of the Americas. Of whom id have thought at least a few have no ancestors among the post 1492 migrants to the Americas. I could well be wrong, but that strikes me as highly surprising, given the existence, esp in North America, of some very distinctive of native life, with large areas having no european contact until well into the 19th cent, and with the limited time for the process to take place since then.

NO contact with Europeans might not be the same as no contact with other indegenous peoples who had some ancestor with Eurasian or African blood. One single great grandfather would be enough of a connection for any person otherwise fully indigenous.

[Ramo]

We know a few:

1) The geographic location was not based on some "genetic center" but a perceived highway conveniently located between the New World and Australasia.

Who said that they assumed the geographic location of this person? It looks like they ran the model everywhere to find the youngest ancestor of humanity.

2) They haven't found genetic evidence for this claim, just a model that allegedly shows it could have happened.

What claim?

3) They claim isolated populations weren't really isolated enough and use the recent European invasion of Tasmania as evidence, but they ignore this invasion was a result of improved sailing vessels and unlikely the further back we go.

Where did they say that? They didn't mention the European invasion in relation to Tasmania.

Here's what the article says:
"Rohde's simulation aims to include everyone alive today, and therefore relies on the assumption that no population has remained completely isolated for any significant length of time. Rohde is confident that this is the case; even Tasmania, once thought to be isolated by choppy seas, contains no people with purely Tasmanian blood."

I'm sure there's more, but a simple logic test should do...

Someone in E Asia had a child who went to SE Asia, had a child who went to New Guinea. Another child left there for Australia and produced children who spread out across the continent procreating with every tribe - and this was done all over the world. One child even found his way to Easter Island and Hawaii... Like I said, mathematically possible but extremely unlikely...

The model in no ways says that the SEAsian guy's kids travelled to every corner of the planet.

[Chemical Ollie]

Originally posted by Combat Ingrid
The central point, I guess, is that you don't need massive migrations to spread the genes around on a global scale. For example, about 10% of all Asian males are descendants of Genghis Khan, IIRC.

Let's make a thought experiment. Imagine a Roman who meets a Chinese woman (who is a descendant of the "common ancestor") during a trading trip to Central Asia. She follows him home and they have two sons. One ends up as a soldier in Britain, and has a few kids with local women. The other one ends up in Spain, likewise having a few kids with local women. Fast forward a thousand years. There will now be thousands of descendants of the original Chinese woman living in Britain and Spain, ready to spread the genes around in the British and Spanish empires. In other words, on a global scale. All that from just one single person.

I'm not arguing it has happened like that, it's just an example to prove my point

OK you PWN me. That's why you're a DOC and I'm just a simple Master

[lord of the mark]

Originally posted by GePap


NO contact with Europeans might not be the same as no contact with other indegenous peoples who had some ancestor with Eurasian or African blood. One single great grandfather would be enough of a connection for any person otherwise fully indigenous.

Understood. An tribe on the upper missouri that had no direct contact with europeans, might have had an indirect contact south all the way to Mexico where there was heavy spanish influence early, etc. And it MAY be that that process is modeled in the paper. But its not clear to me that it is.

BTW a quick websearch has not found much discussion of the dates of the inuit/yupik migrations - started as early as 6000 BCE, but no firm end date. Chukchi displaced inuit/Yupik ancestors in most of NE siberia, but not till almost 1000 CE, and not 100%.

[Al B. Sure!]

it's funny that i'm as dumb as a sack of hammers when i made the same arguements against this test as everyone else did... that the inputs into the program were based on erroneous assumptions concerning migrations, that there were isolated peoples, etc.

[Lul Thyme]

No people have been totally isolated since 3500 BC.
Even if the isolation was jsut broken in the last few hundreds years, with a small population , thats enough for one single individual to be an ancestor of everyone.

Example : imagine some isolated tribe in some island anywhere in the world with a population of 500.
Let's say a foreigner arrives 500 years ago (about 20-25 generations ago).
It would not be suprising at all and in fact more than likely in most cases if today the 500 people are descendant of that one person.

[Lul Thyme]

Although I agree that the assumptions can be discussed and the date change slightly depending on the exact model, no one here could show a single group in the world who COULDNT be descendant from the same person as the rest of the world circa 4000 BC.

[Sava]

AND LITTLE DO YOU KNOW THAT I WENT BACK IN TIME AND FATHERED EVERYOEN ALIVE TODAY!#@!@#!@#!@#

[Berzerker]

Gepap -

the vast majority of people in the new world can pretty clearly trace their lineage back to someone who lived after 1492.

True, it's the Eskimos living in Greenland who appear to have driven the Vikings out (or the weather) I'm thinking about. Or Amazonian Indians that have lived in isolation with encroachments only recently. The article cited Tazmania as an example to shoot down critics who point to isolated peoples, but that invasion (1600?) was made possible by large sailing ships, knowledge, maps, troops, etc...

I agree virtually everyone here "probably" has a recent common ancestor, but further back - 3,500 years still sounds overly optimistic given the lack of corroborating evidence from other fields. And even further back, like 12,000 years - unless the New World saw earlier influxes - for the most isolated groups in the New World. But could a member(s) of that source population arriving around the 1500's (or much later for Greenland) supplant the 2 groups I cited with such recent contact (if at all, we keep finding small tribes or clans in the Amazon region)?

LOTM -

interesting - they modeled migratory behavior - could have used economic models, biological models, or perhaps anthropological models.

That would have been too much work, they are mathematicians after all. But their claim will be checked out in other ways... It's not far fetched if they limited their claim to "virtually everyone"... But I still thnk they're off a few thousand years, around 13,000 before the new world was invaded...

Btw, the Tinglit of Alaska believe the Great Flood occured 14,000 years ago. If they were in the region, some might have been crossing the Bering land bridge at the time and watched the sea (slowly?) engulf about a 1,000 mile wide piece of land.

The question is how did the assumptions in this model match actual historical behavior of the most likely source of old world genetic material into the americas, the inuit? How was the model validated? Surviving neolithic populations? Would these match actual new world conditions 1000 to 3000 years ago? Animal migrations? can these be extrapolated to neolithic humans?

If they push the date back maybe ~5,000 years we might get back to the Tower of Babel and transportation provided by the angry fella in the sky.