http://content.usatoday.com/communities/sciencefair/post/2011/03/all-humans-are-south-african/1

This seems to be an interesting article. But being honest, I don't really understand it. Could someone with a real knowledge of genetics please explain this in layman's terms, if that is possible?

Cabbie would be a better resource, but I will take a stab at it. If I get it wrong, please correct me.

By looking at DNA and comparing DNA from various parts of the world, they can identify differences and similarities. They can project back in time using something called Genetic Drift. From historical records and DNA they know when some early groups moved or split. When this happens they can measure the amount of change experienced in a known time period.

The Semitic markers found in the group in Africa still identify the group as Semitic, but the subtle differences indicate how long ago the split between the main population and the African population took place.

On a larger scale, the early DNA from the American Indians indicate that they originated in Asia. Using the differences or "drift" between the groups you can show how long ago the people left a part of Asia and when groups separated on the American continents. Further information and some specific information can be gained through DNA analysis of archeological finds of early people. I believe they have identified three separate migrations from Asia to the Americas.

Take that on a larger scale, and on a global basis and you should be able to build a bulls eye, especially using forensic DNA on early finds, which would allow you to pin point, with reasonable reliability, the center of the bulls eye.

I hope this is at least as clear as mud.

It is available on netflix instant play for those who have that service. I am traveling right now, using a net card. I don't have minutes for a movie, but will watch it when I get home.

Here is a link to the National Geographic Genographic Project.

https://genographic.nationalgeographic.com/genographic/lan/en/atlas.html

That means I have to negotiate this frickin' dark and treacherous highway myself... Well, here goes, and any other serious anthros or geneticist-types who want to chime in, please do...

First thing, to "saviorself" (I love that one!): I would get a copy of Jared Diamond's "Guns, Germs, and Steel" about human migration patterns and history. It's not the last word on the subject--there never is such a thing--but it's damn good...

JMHO, but Jim's post needs to define "Genetic Drift" in order to clarify matters. And really, the issue is "genetic variability" and just how diverse certain populations are in terms of the number of "original founding DNA contributions" that are present in a given population.

We know Africa was the original homeland of all of our ancestors because the quantities of identifiable and measureable DNA differences (mitochondrial, from the mother, Y-Chromosome from the father, and "autosomal" within the cell nucleus, the most complex of all) on that continent are demonstrably more numerous and variable than anywhere else.

Mitochondrial DNA (mtDNA) which is passed on from mother-to-child with the father making no contribution (there may be rare exceptions, but this is pretty universal) was the first type of DNA evaluated in this manner. It's relatively short ("only" 16,569 "letters") but long enough to yield statistical precision to help pinpoint when changes in those "letters" occurred via a mutation.

See if you can decipher some of what this Wiki article is saying, and you'll be on your way...

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

So if we find a sequence such as AACCTTGTC (it would be much longer, of course) among a population of Africans, and we find similar sequences across the Indian Subcontinent (one known migration route), we can infer what happened. Similarly, if we suddenly see a "AACCTTATC" emerge in populations in India that isn't found in Africa, we can then reasonably infer the mutation arose in that neighborhood (or has to be accounted for by another explanation), and then if we find the new sequence both north (say China) and south (Borneo), we have deduced a probable "route on the map" that early human migration patterns followed.

Okay? BTW, "Genetic Drift" can be understood in part as something as simple as the "number of blond-haired children in Utah." The original "founding population" here was small, but there were large numbers of Scandavians (and blonds from Britain, often with Viking ancestry). Hence, since they've definitely "multiplied and replenished Zion" (displacing the native Shoshones, Utes, Paiutes, and Goshutes), there are larger numbers of blond-haired individuals here than elsewhere.

Such factors require reasonable explanations within the hypotheses being evaluated to account for their presence...

And now to the article at hand, which makes me really nervous because USA Today is strictly a "popular journal," and science reporters are often notorious for misinterpreting material published in peer-reviewed science journals (which, again, are not the last word, but are generally credible).

We know that in the "Out of Africa" migration, people crossed from Africa to Asia. Determining exactly where is problematic, but that is the shortest distance with Yemen probably the most likely candidate.

So that involves East Africa. The study cited offers a claim with supporting evidence that humans arose in South Africa rather than East Africa... So it essentially becomes an anthropological "Where was the Garden of Eden" question...

>Modern humans may have evolved in southern Africa, not eastern Africa as previous research had indicated. A study of genetic markers from six hunter-gatherer groups there found that they have the highest levels of genetic diversity in the world.

>It is currently believed by many in the scientific community that modern humans originated in eastern Africa. That's where the earliest anatomically modern skulls have been found. Also, populations from outside of Africa are made up of subsets of the genetic diversity found there.

Cue up the music for the drama about to appear on the stage... Diamond has some excellent insights on the subtle "politics of scientific consensus," BTW...

I will criticize the author of this piece for not clarifying whether this was a study involving mitochondrial or autosomal DNA (it looks autosomal to me), and that definition of "SNP's" was particularly obtuse ("the researchers looked at 580,000 SNPs, or 'snips among human populations, especially hunter-gatherer peoples in Africa.' These are single-nucleotide polymorphisms, DNA sequence variations that are different between members of the same species. They're often called 'genetic fingerprints,' because each individual has a distinct set of snips."). That looks like a bit of buzzword jockeying rather than a genuine grasp of what was being said.



Edited 1 time(s). Last edit at 03/09/2011 06:17PM by SL Cabbie.

Thank you Cabbie, your explanation helps me understand this better. I can see that this is an area that will take some study, but at least I feel like I can get started with it.

The Mark of Cain must be White skin...


Ahhahahahahaaaa yes, that is pretty funny.

There's a chapter "How Africa Became Black" on that subject...

It would be nice if it were cut-and-dried to toss in certain faces, but...

And "racial" differences between people are miniscule on the grand genetic scale...

I've told my TBM mom many times that we all came from Africa and migrated from there. She gets very quiet.

I think to myself hee, hee, we are NOT from Missouri!!!

Interesting isn't it. I've watched evolution shows with my parents. I always check to see if there is one on the science channel or NatGeo when I'm visiting. I always watch it, saying I want to see if it's something I can show my students. It's so strange because they will accept what they see, in fact I grew up watching science shows with my dad, but nothing will shake their belief. Well I was the same way once, trying to believe in both. I know the DNA evidence about Native Americans has shaken my dad, but he just replies that he trusts God and believes in the church so there must be a logical explanation.

For what it is worth

http://www.youtube.com/watch?v=wDknzZ9b6rg&tracker=False

This video offers some reasonable explanations on an elementary level, but one could drive a truck through some of the later claims, and I think he ruins his credibility as a result.

An example is that "DNA path" shown progressing from Australia up Indonesia along the South China Sea to Japan and purportedly to the area of the Bering Strait/Beringia (Where Native Amercans entered the New World between 12-20,000 years ago). There are at least two or three more parsimonious explanations I can find for that one...

And that "farming arose out of necessity" in drought conditions is at odds with a number of views; there are many who believe that farming, overgrazing, and human habitation gave rise to "desertification" in some areas, and the study of climatology in the past is hardly the cut-and-dried scenario he affords. The only place it "coincides perfectly" with the DNA evidence is in this guy's imagination. There's a ton of stuff that still needs to be ironed out...

Too, there's a claim about "Cheddar Man," the 9,000 year old Briton whose DNA was sequenced. That one's a scientific howler. The video says a teacher in the town was identified as a "direct descendant," while the evidence only points to a relationship with a common ancestor. Wiki has it right here...

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

>It produced two exact matches and one match with a single mutation. The two exact matches were schoolchildren, and their names were not released. The close match was a history teacher named Adrian Targett. They, like anyone else carrying haplogroup U5 today, share a common ancestor many thousands of years ago with Cheddar Man through his maternal line.

Cheddar Man may or may not have been a direct ancestor of this fellow--or indeed the whole village--but the DNA says nothing one way or the other.

Finally, I happened upon another video by this individual. It was a defense of "Intelligent Design," for crying out loud...

http://www.youtube.com/watch?v=irVqVKdiohE&feature=mfu_in_order&list=UL

Never mind that the Michael Behe talking points he's parroting have been roundly thrashed, he impeaches his own case with his unwarranted fictionalized extrapolations above...

>> "Finally, I happened upon another video by this individual. It was a defense of "Intelligent Design," for crying out loud..."


Ummm....read the description, and watch the video again. You must be tired tonight. Potholer makes videos against ID/creationism. Point it out to him if it bothers you, he might appreciate the feedback. He actualy has updated his videos before, correcting mistakes pointed out by others. I doubt many creationists would do the same.

I drove the ol' police interceptor down the road, and there was that big crater, and I got my flashlight out and peered over the edge, and there was this big giant turd that may or may not have had eyes; I didn't stick around to investigate, however, since a turd is a turd is a turd... Nothing intelligent there, particularly given its location. If you want to insist on somebody being tired, I'll suggest it was whoever drove it into that hole... But to me it looked like a dumbass operation and not fatigue...

There's a sarcastic moment at the end where a "loving God" who "created bacteria" is mocked, with pictures of children struck down by disease, but artistically that bit of subtlety--if that's what it was--is lost with statements such as...

>"So however reluctantly I must agree with the Creationists."

Testing your hypothesis, at best it amounts to couching a philosopical argument (see Blake, William, "Thinking as I do that the Creator of this world is a very cruel being") in something opaque and obtuse.

And on a "meta-level," it amounts to an admission that the speaker can't refute the I.D. arguments, either, and thus must resort to obfuscation that appears erudite but is, in fact, assinine.

Satire is a legitimate art form; science and science reporting need to rely on straightforward interpretation to avoid ambiguity. If sarcasm fails to reach its intended receiver, it's almost always the fault of the sender.

I stand on my characterization of that stinkeroo about "Cheddar Man" and his purported descendant in the first video link "Dapperdan" provided... Extracting 9,000 y.o. mtDNA is reasonable, exciting, and challenging, but as I noted it only provides proof of a common ancestor along the maternal line. "Potholer" calls Cheddar man a "direct ancestor."

And I note some videos on global warming follow; I didn't mention those because it's close to political, but I sent an e-mail to a friend who works in the field asking for his unvarnished reaction. My initial reaction was they were the works of an attention ho'.... They amounted to a sanctimonious and shallow presentation of science I would expect from a theologian defending religion and not from a genuinely enlightened sort.

I wanted to watch something like that to learn, and this guy's poor impersonation of a pedagogue (I was a teacher once, remember) left me shaking my head. Silly me and those darned expectations (and yes, that was sarcastic).

Guy reminded me of that junior high biology teacher from BYU I had back in the '60's...



Edited 2 time(s). Last edit at 03/10/2011 08:37AM by SL Cabbie.

saviorself, If the oldest human remains are found in south Africa, I would guess the earliest humans lived there.

The earliest anatomically modern human remains have been found in East Africa... Whether earlier forms will be found eventually in South Africa is part of the issue at hand.

The debate on this one will focus on the "assumptions" made in order to construct the statistical model, and I'm guessing (and I've never had a class in statistics, just some education in probability theory coupled with playing certain card games and backgammon for years) the devil will be in the details. We know the various "bushmen" tribes are among the "oldest" examples of humanity, but the displacement that may have taken place in antiquity is liable to fuel considerable debate. And yet the numbers only involve their presence in an area for 40,000 years or more, and modern humans have probably existed for 100,000 years or more.

And then there's that matter of the "Nenderthal DNA" that was recently hyped. The video I panned above didn't take that issue into account, which was one factor that led me to suggest speculation was being offered as fact. The fact is that the same sequences "identified as Neanderthal" are found in Australia as well as England, and the model proposed didn't address that matter.

As usual, you are right on top of the information. Whether east or south Africa, it looks like that is the continent of our origin.

And remember that we are not considered to be directly derived from Neanderthal, though there may have been crossover breeding. From what I have read our ancestors were contemporary with the Neanderthal in prehistoric Europe.

I am going to have to get some books and do some reading, since the question as to the origin of modern humans is no cut and dried simple matter. I thank you all for your contributions to my enlightenment, especially Jim and Cabbie.

Thanks Cabbie. One thing leaving the church taught me was to express appreciation for people proving my prior knowledge wrong.
So thank you.

But the stuff that was out there was, well, out there... And I'm still nervous that there are some "cultural factors" operating... Oh well...

It's kind of funny, but what first triggered my radar was his pronunciation of the word "cytosine." I double-checked that one (since it was a BYU-sort I first heard it from in 1967), and it became clear this was a largely self-educated individual who could've benefitted from interactions and feedback from others to keep his imagination and perceptions in check...

There are huge honest areas of debate on these issues where matters are unresolved, and I'm grateful I was offered an education where I learned to frame both sides of an issue before evaluating the factual evidence.

And if I screw up (and I have), there are even a couple here who will correct me... Most gently, but most thoroughly, thank the universe...