source?

Doubtful.

>>4608832
http://tedlab.mit.edu/~dr/Papers/Rohde-MRCA-two.pdf

>>4608825
Isn't that awesome?!

Nah, he's far older than that.

>>4608843
not according to the MIT model

is this sorta like x degrees of separation?

>>4608846
i guess so. people get around, and when they do they fuck

2000 years ago... as in still within the CE....Umm but land bridge, land bridge, land bridge, land bridge.... closed about 6000 years ago


>>Crock shit

>>4608843
you are probably thinking of the strict maternal (mitochondria) and strict paternal (y-chromosome) studies

obviously each person only has 1 each of those, but if you allow your father's mother's mother's father, etc, it becomes a lot more recent

>>4608854
they estimate about 3 people per year cross nautical bridges by boat

land bridges are only necessary for population migrations, not individuals

>>4608863
then they did a simulation where they reduced that by many factors and it didn't change anything much

you only need a very occasional explorer/stray to cross and fuck someone and very soon everyone is their ancestor too

>>4608854

Estimates put the MRCA somewhere closer to 4000-5000 years before present.

Also, what are boats?

I skimmed parts of the paper. This doesn't fit with anything else I've read on the subject, so I'm very skeptical.

http://en.wikipedia.org/wiki/Recent_African_origin_of_modern_humans
This is the mainstream theory of human. It is a lot more than 2-3000 years ago that humans wandered out of Africa and the populations became isolated.

Besides, if it was only 2-3000 years ago, then there would not be the large differences between the populations that we see.

>>4608910

We’re talking about the most recent common ancestor, not the origins of the whole scope of the human genome. The MRCA is just the most recent ancestor, not the most recent carrier of all currently present human DNA.

>>4608865
>> implying that within 5000 years enough fucking occurred through a large area, such as the Americas, was able to spread a specific genome to every person

>>no way in hell it could happen, paper is pure bullshit

>>The percentage of males born into the population was
set at 50%.

>>first example the percentage of males has never been 50%, war, famine etc is not calculated properly into this 'study'.

>>Secondly they assumed migration was simply and easy. This has never been true. Look up migration studies, once the initial migration occurred it is nearly impossible to place a new group in its place(not impossible but longer than 5000 years or a systematic 'cleansing').
>>CROCK SHIT

>>4608913
They must be using that term in some strange way. I do not for one second believe that the 'MRCA' was only 2-3kyo. How wud that even work? Some man or woman in Eurasia and their children travel as far as possible away from that and breed on the way?

I did a quick search, but didn't find a ref. But I seem to remember that mutations travel at about 50 miles/generation. Given 3000 years, and a generation of 20 years, that's only 150 generations, which is 7500 miles. Not enough to get around the Earth. Not even close.

>>4608863
so an indian crossed the atlantic in a dugout and began fucking every woman in Europe in the last 5000 years? Highly doubtful. This sounds like "we are the world" wishful thinking.

>>4608865
>you only need a very occasional explorer/stray to cross and fuck someone and very soon everyone is their ancestor too

I doubt that even in a smaller country like Denmark, there was a RCA in the last 3000 years. 10000 perhaps. It depends also on social mobility. With the caste system in India resulting in lower social mobility and a huge population and area, the MRCA should be pretty far back. No don't believe for a second it was within even 3000 years for India.

no one here understands coalescent theory

/sci/ blows

>>4608943
>But I seem to remember that mutations travel at about 50 miles/generation.

Whether that figure has any basis in reality, it's obviously a rule of thumb/average, not a speed limit. It is not impossible for a person to travel more than 50 miles from his place of birth.

>>4608947
>I doubt that even in a smaller country like Denmark, there was a RCA in the last 3000 years. 10000 perhaps.

Well, you're wrong.

Google the author of the paper.

He is not a biologist.

30-40,000 years ago is more like it.

>>4608944
>so an indian crossed the atlantic in a dugout and began fucking every woman in Europe in the last 5000 years? Highly doubtful.

That would be highly doubtful if anyone was suggesting that. Luckily, you don't need any single individual making huge journeys or having huge numbers of offspring.

>>4608965
ten points for autism.

>>4608964
>30-40,000 years ago is more like it

Based on what? Your gut feeling? Most estimates put it between 5000 and 2000 years ago.

>>4608969
>say something retarded
>someone points out you said something retarded
>LOL I TROLLED U!!!! U SO ASPIE!

>>4608955
It was an average for early hominids IIRC.

>>4608964
No, but he seems cool. I still don't believe his model. I will read the entire paper later. Actually, the existence of small very in-bread populations around the world rather well disproves this model (that are isolated). There is no way one could reach all of them in a mere 2-3k years.

Maybe we should get Razib to look at this.

Fun fact: almost all humans are direct descendents of the Egyptian pharaohs, and would technically be in the line of succession.

Pic related, every ITT's great great.... great grandfather.

Okay, could /sci/ explain this to me? If humans originated 200kYA, wouldn't the most recent common ancestor be 200kYA? My mind is full of fuck.

>>4608986
> Okay, could /sci/ explain this to me? If humans originated 200kYA, wouldn't the most recent common ancestor be 200kYA? My mind is full of fuck.

Yes, you are confusing the LCA of two species (during speciation) with a MRCA within a species.

http://en.wikipedia.org/wiki/Most_recent_common_ancestor
"The term MRCA is usually used to describe a common ancestor of individuals within a species. It can also be used to describe a common ancestor between species. To avoid confusion, last common ancestor (LCA) or the equivalent term concestor is sometimes used in place of MRCA when discussing ancestry between species."

>>4608978
>There is no way one could reach all of them in a mere 2-3k years.

I wouldn't be sure about that. Think about it. Say a group is *completely* isolated for 500 years. I don't think any such group exists, but it can be a working estimate. Then the last outsider to inject genes still has 1500-2500 years to be descended from the MRCA along ANY possible vector.

Amazing but not incredible.

>>4608992
Yeah, I get that there's a difference between LCA and MRCA, but how could the MRCA be so much different than the LCA? As the human population grew and spread across the planet, it would seem to me that the MRCA would remain the LCA.

Obviously I'm not denying that you're right; I'm just having trouble seeing how a diverse and large group of animals within a species could suddenly have a new common ancestor.

>>4608998
>I wouldn't be sure about that. Think about it. Say a group is *completely* isolated for 500 years. I don't think any such group exists, but it can be a working estimate. Then the last outsider to inject genes still has 1500-2500 years to be descended from the MRCA along ANY possible vector.

Yes, i get that. But consider how many of these isolated tribes there are around the world. For a MRCA to be only 2-3kyo, that ancestor wud have had to have children that somehow got into contact with ALL of these isolated peoples before they were isolated. I don't think so. And if there is just one of them that has been isolated for more than 2-3ky, then the model is proven wrong. Note that "isolated" here means only genetically isolated, so no breeding with outsiders. Contact is fine, just no breeding.

But even ignoring these isolated peoples, i don't think the model is correct. Think of the human tendency of endogamy. It is rather hard for one person to get ancestors from all the major population groups. He wud need to conquer endogamic practices for every such population.

>>4609012
>Obviously I'm not denying that you're right; I'm just having trouble seeing how a diverse and large group of animals within a species could suddenly have a new common ancestor.

I'm not the one making the claim. In fact, I'm one of them arguing against the model.

It wud work like this: The MRCA dude (most likely a guy!) had a lot of children some long time ago. These children very both attractive and very adventurous and so they traveled away from their origin, each in different directions. Along the way, they had as many children as possible. For this to work, this pattern needs to be repeated alot of times until all human populations are reached.

>>4609025
>For a MRCA to be only 2-3kyo, that ancestor wud have had to have children that somehow got into contact with ALL of these isolated peoples before they were isolated.

Which would not be at all a problem. The vast majority of all humans do not live in extreme isolation. The MRCA of, say, 95% of humans would be much more recent than the MRCA of 100% of humans. If that isolated group had contact with ANYONE, it is very likely that that someone is either part of the "mainstream" or not far removed from it.

>>4609038
>It wud work like this: The MRCA dude (most likely a guy!) had a lot of children some long time ago. These children very both attractive and very adventurous and so they traveled away from their origin, each in different directions. Along the way, they had as many children as possible. For this to work, this pattern needs to be repeated alot of times until all human populations are reached.

That is not how it would work at all. Normal human interaction is all that is required. You're thinking about it in terms of a few generations when we're really talking about dozens and hundreds of generations. The spread is literally exponential, and you seem to be thinking linearly.

>>4609038
K thanks. Seem really unlikely tho...

>>4609057
So, how would it work then?

>>4608971

Computer simulations are only showing what could possibly have happened based on genetic algorithms. This is so fundamentally inconsistent with everything else we know. We can place, with carbon evidence and ground soil, civilizations in india simultaneous with humans in europe and north america over 5000 years ago.

>>4609057
>That is not how it would work at all. Normal human interaction is all that is required. You're thinking about it in terms of a few generations when we're really talking about dozens and hundreds of generations. The spread is literally exponential, and you seem to be thinking linearly.

As i explained it above, it wud be exponential and not linear and i understand that just fine, but still don't think the model is correct. Even disregarded possible isolated peoples hiding in jungles and what not.

The migration speed of these children wud need to be crazy high. How far does one need to travel from one point on Earth to reach all other humans? Thousands of kilometers, and most of that by foot.

>>4609071
>Computer simulations are only showing what could possibly have happened based on genetic algorithms. This is so fundamentally inconsistent with everything else we know. We can place, with carbon evidence and ground soil, civilizations in india simultaneous with humans in europe and north america over 5000 years ago.

This is not inconsistent with the model.

Think about it this way. Say I have three children. My children each have three children. Their children, on average, have three children, and so forth. In a dozen generations that's over half a million direct descendents.

In two dozen generations, it's almost 300 billion.

Obviously, those aren't all different people. They all interbreed. But it's clear that in only a few hundred years, everyone who is remotely part of the gene pool is descended from me many times over - perhaps millions of times over. If anyone from this gene pool interbreeds with another, they can then similarly be the millions of times over ancestor of the common gene pool. It only takes very rare interbreeding, nothing remarkable, for everyone to be descended from the same person.

Check Wiki's article on uncontacted peoples.
http://en.wikipedia.org/wiki/Uncontacted_peoples

"The Sentinelese continue to actively and violently reject contact. They live on North Sentinel Island, a small and remote island which lies to the west of the southern part of South Andaman Island. They are thought to number around 250 (median estimate). Based on helicopter surveys of the island, the 2004 Indian Ocean tsunami does not appear to have affected the Sentinelese adversely.

It is estimated that they have lived on their island for 60,000 years. Their language is markedly different from even other languages on the Andamans,[5] which suggests that they have remained uncontacted for thousands of years. They are thus considered the most isolated people in the world, and they are likely to remain so.[5]"

Altho the source for that is not excellent (not academic).

most men are descended from genghis khan

mongols raped their way across asia, middle east and north and eastern europe yo

>>4609078
>How far does one need to travel from one point on Earth to reach all other humans?

No offense, but if you're asking that question, you obviously don't understand it just fine.

i think what a lot of people are missing is that the MRCA can change after the fact. for example, perhaps 100 years ago there were still a few lines left that were not from the current MRCA, but they have since died out. So it's not necessarily a bottleneck to one person, just a bottleneck

>>4609086
You need to add that you mean 3 children that live to breed themselves and actually do so, and also generally do that somewhere else than where the parent was.

Given the low survival rates, one wud need to have lots and lots of children. That is also necessary if even some of those children are supposed to migrate (and remember the high migration speed necessary!). Obviously, if they stay in the same place as these uncontacted peoples have done, it will not help anything that each successive link had 3 children.

Also consider sex-linked differences in migration. One wud also need to have children of the correct sex.

Too implausible man, i can't believe it.

>>4609100
>most men are descended from genghis khan

No, they are not.
http://en.wikipedia.org/wiki/Descent_from_Genghis_Khan
"Zerjal et al. (2003)[7] identified a Y-chromosomal lineage present in about 8% of the men in a large region of Asia (about 0.5% of the men in the world). The paper suggests that the pattern of variation within the lineage is consistent with a hypothesis that it originated in Mongolia about 1,000 years ago (thus several generations prior to the birth of Genghis). Such a spread would be too rapid to have occurred by genetic drift, and must therefore be the result of selection. The authors propose that the lineage is carried by likely male-line descendants of Genghis Khan and his close male relatives, and that it has spread through social selection. Both due to the power that Genghis Khan and his direct descendants held and a society which allowed one man to have many children through having multiple wives and widespread rape in conquered cities.[8]"

In other words, a small percentage in a large part of the world are descended from DK by male DNA (Y-chromosome). Not even close to every man in the world. This rather nicely illustrates with even with extreme social conditions, it takes a lot of time to reach 100% penetration, even if a 'nearby' population.

>>4609102
>No offense, but if you're asking that question, you obviously don't understand it just fine.

I was not talking about a single man traveling all the distance by himself, if that is what u thought that i thought.

But the sum of the distance migrated of all descendents from the MRCA be the distance to every human population. This is slightly bad formulated, but the general idea is fine.

>>4609107

Three surviving children as an average is totally reasonable. Otherwise the population wouldn't grow at all, and obviously it does.

And no, they don't have to be in different regions. As I explained, only very rare travel is necessary, nothing extraordinary.

>>4609119
>But the sum of the distance migrated of all descendents from the MRCA be the distance to every human population.

Nowhere on Earth takes thousands of years to get to.

>>4609120
>Three surviving children as an average is totally reasonable. Otherwise the population wouldn't grow at all, and obviously it does.

It needs to be 3 surviving descendents that each also have children that survive, reproduce and in general migrate etc.

Ofc populations increase now, but they haven't always done so. However, it seems that they have been doing that for long enough for this to work.

http://en.wikipedia.org/wiki/World_population_estimates

>>4609126
>Nowhere on Earth takes thousands of years to get to.

Not if one travels only, obv., but if one also has to successful foster children along the way. That takes time.

its a stupid thing to model

who cares about this? its a curiosity