Humanity's Common Ancestor Only ~3500 Years Old

[Al B. Sure!]

I'd say the Middle and Near East have seen more traffic more consistently...

or the Central Asian Steppe... the Caucasus mountains also saw quite a bit of movement

[Ramo]

I heard SE Asia on NPR. Dunno which one it is. The guy seemed pretty unsure about it himself.

It hasn't seen the most migrations of people, it just will get your genes distributed around the world the quickest (since the Americas, and Oceania are nearby - and the ocean route needs to compete with the land route to Africa).

[Berzerker]

Everything in science is a model based on assumptions.

And not every model is factual because some assumptions are false.

You say that, yet you don't have a single clue as to what the assumptions are, much less whether or not they are wild.

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.

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

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.

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...

[MrFun]

Originally posted by Ramo

What I was questioning, is if this shows that HOMO SAPIENS were not the ones who actually founded the first civilizations, but that a different Homo species did.

No, that has absolutely nothing to do with what the article refers to.

[Combat Ingrid]

I don't understand why it's so controversial that most of us have some common ancestors just a few thousand years back. Just think about the six degrees of separation rule. This is basically the same thing.

For each generation back, you double the number of ancestors. You have two parents, four grandparents and so on. After 100 generations you have 2¹⁰⁰ (10³⁰) ancestors. Lets say one of your ancestors 50 generations back married a Chinese, you would suddenly have 2⁵⁰ (10¹⁵) Chinese ancestors. Conversely, one single person doesn't need to procreate much as the number of descendants will increase in a similar manner.

[tinyp3nis]

Originally posted by Combat Ingrid
I don't understand why it's so controversial that most of us have some common ancestors just a few thousand years back. Just think about the six degrees of separation rule. This is basically the same thing.

For each generation back, you double the number of ancestors. You have two parents, four grandparents and so on. After 100 generations you have 2¹⁰⁰ (10³⁰) ancestors. Lets say one of your ancestors 50 generations back married a Chinese, you would suddenly have 2⁵⁰ (10¹⁵) Chinese ancestors. Conversely, one single person doesn't need to procreate much as the number of descendants will increase in a similar manner.

10^30 is more than the combined sum of all people who ever lived. So it can't be as simple as 2^100.

[Combat Ingrid]

That's because the same ancestors will show up over and over again, in different branches of the family tree. We're all inbred you know

[Sikander]

Originally posted by Gangerolf

Nonetheless, the results show that we are one big family, Rohde says. As he and his colleagues write: "No matter the languages we speak or the colour of our skin, we share ancestors with those who planted rice on the banks of the Yangtze, who first domesticated horses on the steppes of the Ukraine, who hunted giant sloths in the forests of North and South America, and who laboured to build the Great Pyramid of Khufu."

Kumbaya

[Chemical Ollie]

If it's published in Nature, it carries some dignity, but I am sceptic for reasons others already pointed out. If you look at a certain region, you could expect this, but significant migration and cross-breeding on a global scale is a quite new phenomenon.

[Moral Hazard]

This is the craziest thread I have ever seen. Everyone discussing an study which no one has read. Has any one read the study? I do however find it hard to believe.

[pchang]

Originally posted by Caligastia



You actually believe that everyone alive today is descended from one person. Your delusion has reached new heights. It's actually pretty sad to see someone so blind.

This is not what the article claims. You need to read a bit more closely.

[MikeH]

Originally posted by Caligastia



You actually believe that everyone alive today is descended from one person. Your delusion has reached new heights. It's actually pretty sad to see someone so blind.

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.

[Chemical Ollie]

Using a mathematical model that ignores imbalances in global migration and breeding patterns would get a result like this. I don't want to spend my whole coffe break to find out which model they have used, but I'm sure it's more complicated than the one MikeH showed. I don't think a study based on an over-simplified mathematical model would be published in Nature. But I do think that any in-data would be guesses and rough estimations, so a very complicated model could still give false results.

There is a generic rule that I try to keep in mind whenever I'm involved in science or music recordings and a lot of other situations: No matter how sophisticated systems you have, if you feed them with crap they will give you crap back.

[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

[GePap]

Agreed.

Also, we have to remember that we are talking about living populations- remember for example that the vast majority of the Naitve Populations of some iolated areas were wiped out by disease when peoples from Eurasia-Africa arrived, lowering the possibility that decendents would be born utterly isolated from the new populations.