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Frans_Jozef
Friday, January 12th, 2007, 12:18 PM
Spread Of Modern Humans Occurred Later Than Previously Thought, Profs Say


The spread of modern humans out of Africa occurred 40,000 to 50,000 years later than previously thought, according to researchers including one Texas A&M University anthropologist.

Ted Goebel, associate director of the Center for the Study of the First Americans at Texas A&M, is the author of the paper titled “The Missing Years for Modern Humans” that appears in the Jan. 12 (Friday) issue of Science.

Goebel’s paper is one of three published in the current issue of Science dealing with the origins and dispersals of modern humans during the Ice Age. A fourth paper appeared in a previous issue of the journal.

The other papers are written by human paleontologist Frederick Grine of Stony Brook University, geneticist Annamaria Olivieri from the University of Pavia in Italy, and archeologists Michael Anikovich and Andre Sinitsyn of the Russian Academy of Science and John Hoffecker of the University of Colorado.

“All of them have one thing in common,” says Goebel of the papers. “They are all trying to investigate and demonstrate when it was that modern humans evolved in Africa, left Africa and colonized different areas of the Old World.”

Previous theories held that modern humans spread from Africa 100,000 years ago. New data, however, suggest that their migration occurred only 50,000 to 60,000 years ago, Goebel argues. Additionally, the spread of modern humans in eastern Europe and Russia occurred earlier than previously thought notes Goebel.

The new information, according to Goebel, is based on paleontological evidence of human fossils including a modern human skull from Hofmeyer, South Africa that was discovered in 1952, mitochondrial DNA used to research modern human dispersal from western Asia and archeological evidence from artifacts found at the Kostenki sites along the Don River in Russia.

Using a combination of dating techniques on the skull, Grine and his colleagues determined that sediment in the skull’s endocranial cavity was deposited 36,000 years ago. According to the authors, the Hofmeyer skull is more similar to modern humans of Upper Paleolithic Europe than recent South Africans or Europeans and has little in common with Neanderthals.

“The idea is that modern humans developed around 100,000 years ago or so in east Africa,” says Goebel. “When they developed the physical and behavioral repertoire that we consider to be modern, they then successfully colonized new areas. This new evidence suggests that modern humans spread out of Africa very late in the Pleistocene era.”

The DNA analyzed by Olivieri suggests that two genetic lineages originated simultaneously in western Asia between 40,000 and 45,000 years ago and from there spread into northern Africa. And artifacts found at the Kostenki sites led researchers to believe that part of central Eurasia and Russia were colonized just as early as Europe by modern humans.

“Why is it such a big deal? The big deal is we have these models that we use to explain the origin and dispersal of modern humans,” says Goebel. “But we still don’t have all of the evidence required to test these models – to disprove or prove them.”

“What we have are three pieces of the puzzle and they help us test the new theory and all pretty much support this notion that modern humans evolved in Africa and then they spread from Africa.”


Texas A&M University
http://www.tamu.edu/tamunews/

Agrippa
Friday, January 12th, 2007, 06:57 PM
One should compare this with the article about the new findings in Russia being posted here:
http://forums.skadi.net/traces_europes_earliest_modern_humans_di scovered_russia-t88114.html

As well as with what Dienekes wrote on the issue and I think is very interesting viewpoint if comparing different ancient and already separated strains of early sapiens in Africa:
http://dienekes.blogspot.com/2007/01/new-kostenki-finds-in-science-magazine.html

One thing is clear, those Cromagnid-Aurignacid early modern sapiens Europeans should have had a (longer) time of differentiation from the basic pool of archaic sapiens before they entered Central-Asia and Eastern Europe which classic anthropologists like v. Eickstedt already considered as a reservoir for early (Proto-) Europoids many decades ago.

SuuT
Friday, January 12th, 2007, 09:16 PM
I just question the amount of time that is proposed as being enough to account for the amount of phenotypic (and even genotypic) variation present in modern population groups - especially considering the amount of time it takes for Y-chrom splits etc.: it must have been remarkably fast and then slowed to a crawl, if not a stop, if these proposals be true.

Dr. Solar Wolff
Saturday, January 13th, 2007, 04:53 AM
I do not understand this statement from the article:

___________

The DNA analyzed by Olivieri suggests that two genetic lineages originated simultaneously in western Asia between 40,000 and 45,000 years ago and from there spread into northern Africa.
____________

It sounds like they are saying sapiens originated in Western Asia and then spread into Africa rather than the other way around.

Does anyone have links to the original paper(s)?

Dr. Solar Wolff
Saturday, January 13th, 2007, 05:10 AM
One should compare this with the article about the new findings in Russia being posted here:
http://forums.skadi.net/traces_europes_earliest_modern_humans_di scovered_russia-t88114.html

As well as with what Dienekes wrote on the issue and I think is very interesting viewpoint if comparing different ancient and already separated strains of early sapiens in Africa:
http://dienekes.blogspot.com/2007/01/new-kostenki-finds-in-science-magazine.html

One thing is clear, those Cromagnid-Aurignacid early modern sapiens Europeans should have had a (longer) time of differentiation from the basic pool of archaic sapiens before they entered Central-Asia and Eastern Europe which classic anthropologists like v. Eickstedt already considered as a reservoir for early (Proto-) Europoids many decades ago.

From the first article cited by Agrippa:
___________
"A bone chemistry analysis from 30,000-year-old human remains indicates a high consumption of freshwater aquatic foods -- either water birds, fish, or both --"
_________

Early sapiens are frequently found in association with water and water-derived food as opposed to Neanderthals who did not eat fish or seafood.

From the second article cited by Agrippa:

____________
From the New York Times:

An international team of researchers reported today that the age of the South African skull, which they dated at about 36,000 years old, coincided with the age of and closely resembled the skulls of humans who were then living in Europe and the far eastern parts of Asia, even Australia.

The discovery of these resemblances lends some support to the idea that I have expressed previously that only a subset of modern humans (which I have called Afrasians) was responsible for the colonization of Eurasia. At the time frame in question, these resemblances would have been marked, since (i) intermixture with pre-existing populations (such as "Paleoafricans" or pre-moderns in Europe) did not have time to take place yet, and (ii) racial differentiation had only just begun. This paragraph says it all:

Because the Bushmen are well represented in the more recent archaeological record, Dr. Harvati said, they were expected to bear a close resemblance to the Hofmeyr skull. Instead, the skull was found to be quite distinct from all recent Africans, including the Bushmen, she said, and it has “a very close affinity” with fossil specimens of Europeans living in the Upper Paleolithic, the period best known for advanced stone tools and cave art.

“Much to my amazement,” Dr. Grine said in an interview, “the skull linked very closely with those from Europe at the time and not with South African remains 15,000 years on.”

The dissimilarity to recent Africans of the Hofmeyr skull can be easily explained if it is understood that recent Africans are not only descended from the "Afrasians" that I have spoken of, but also from the older "Paleofricans" whose existence can be inferred both by genetics (human mtDNA and Y-chromosomes are older than the ~40kya mark) and paleoanthropology (modern humans such as Omo and Herto are 100-200kya old).

It also stresses the idea that contrary to popular treatments such as Spencer Wells' Journey of Man, the appearance of African hunter-gatherers such as the Khoi-San should not be used as a model of what mankind's earliest African ancestors looked like
____________________________

The Paleoafricans resembled the grade called Homo heidelburgensis in Europe to with the famous mandible as well as the Rhodesian skull in Africa belong. These people would have mixed with the "Afrasians", later, in this interpetation but the Afrasians would first colonize Europe and Asia and there also mix with the local populations giving us Black Africans, Europeans, Asians (all of hybrid ancestry) and the Bushmen-types which are more like the original Afrasians.

SuuT
Saturday, January 13th, 2007, 02:24 PM
I do not understand this statement from the article:

___________

The DNA analyzed by Olivieri suggests that two genetic lineages originated simultaneously in western Asia between 40,000 and 45,000 years ago and from there spread into northern Africa.
____________

It sounds like they are saying sapiens originated in Western Asia and then spread into Africa rather than the other way around.



I found that abmiguous, as well. I believe that they are referencing 2nd and 3rd wave migrations after the first 'out-of-Africa' event, in which some groups actually returned to the African continent (primarily the North) bringing with them a fresh influx of gene variation etc.

Another thing I don't understand is how not only this new time table conflicts with genetic drift, but how the re-entry of a once 'indigenous' population back into North Africa, shows of more genetic European influx than Asiatic. (?)

Liberator Germaniae
Saturday, January 13th, 2007, 04:50 PM
An international team of researchers reported today that the age of the South African skull, which they dated at about 36,000 years old, coincided with the age of and closely resembled the skulls of humans who were then living in Europe and the far eastern parts of Asia, even Australia.



When reading this string it came to my mind that human remains known as the "Otjiseva Man" were found in 1964 on the Farm Otjiseva, some 26 miles northwest of Windhoek in Namibia on the edge of the Khomashochland (a central highland). In the first publication on the remains, "Report on some Fossil Human Remains from Otjiseva", author Wolfgang Sydow from the S.W.A. Scientific Society (presently Namibia Scientific Society) (1970) wrote the following introductory remarks:

"It is therefore quite understandable that the remains of Otjiseva man were at first taken as potsherds by its finder who handed them to me as such on the evening of the 16th of June, 1964. The "sherds" which had a fairly even thickness of up to 10 mm were covered with a thick yellow-grey crust but showed an almost white fracture revealing bone tissue. The preliminary reconstruction of the more than twenty odd fragments resulted in a well-rounded, fairly large cranium. Here and there pieces were missing but the overall size and shape were already clearly recognisable. Although I am not a trained specialist in this field the skull seemed to me to belong to a very robust and big-headed individual, and looked not too modern." (More: http://www.namibiana.de/index.cfm?action=ViewDetails&itemid=723)

To cut a long story short: No exhausting studies have been made on the remains of the Otjiseva Man, who is thought to have lived in the area of present-day Namibia in ca. 10000 BC. The find is now said to be missing: Apparently members of the Smithsonian Institute had requested the pre-Independence (pre-1990) director of the present museum’s forerunner, the State Museum, to have a look at the bones. After initially declining their repeated requests, the hesitating Director eventually agreed to open the box, only to discover that it was empty! The only curator who has had access to the find has been suspected of having stolen the bones for unknown reasons, but the police never investigated this case.

SubGnostic
Saturday, January 13th, 2007, 11:31 PM
I just question the amount of time that is proposed as being enough to account for the amount of phenotypic (and even genotypic) variation present in modern population groups - especially considering the amount of time it takes for Y-chrom splits etc.: it must have been remarkably fast and then slowed to a crawl, if not a stop, if these proposals be true.

From "Race - The Reality Of Human Differences", by Sarich and Miele:


...The problem for several years was the fact that the Y-chromosome DNA evolves at a rate similar to that for the rest of the nuclear DNA (1.25 percent per 10 my [!million years] per lineage); thus two humans whose Y-chromosome lineages were 100,000 years old would have only one substitution for every 4,000 base pairs. In other words, you would, on average, be examining 4,000 base pairs to find a single variant. Clearly, a screening procedure was needed to identify manageable pieces of DNA containing a variant, and that was provided by two of the Stanford group, Peter Underhill and Peter Oefner. Just how much they found was indicated in an article they published ni 2001 in which they reported on 218 variants, of which 13 have been found by all other groups, and 205 by theirs.
In June of the previous year, the same group at Stanford had published the first reliable Y-chromosome dates in an article of major importance that, most appropriately, was published in the first year of the new millenium. In "Population Genetic Implications from Sequence Variation in Four Y-Chromosome Genes," the thirteen coauthor described finding 1,067 substitutions separating humans and chimpanzees at the 78,399 positions sampled. At the same time, they looked at 53 humans from all over the world and found, first, the standard three-deep lineages that are African and then an out-of-Africa limb branching out from one of those three that now contains most Africans and all non-Africans. The modern humans belonging to this out-of-Africa unit differed from one another by about 6.5 substitutions.
In crude term, the time of most recent common ancestry is the human-human difference divided by the human-chimp difference (6.5/1,067) times the human-chimp divergence time (5 million years) - note how useful it is to have that date - which equals about 30,000 years ago. The terms are "crude" because a difference of 6.5 is small, and it is unknown to what extent current variation in the species reflects a sudden expansion in numbers beginning with its origin. But the precise date is not that important, just as it wasn't for the human-chimp study thirty-five years ago. Nonetheless, the quantative similarity to that earlier situation is striking. First, the estimated albumin difference was close to 5 substitutions and certainly not more than 10. Second, limits could be put on the possible dates involved. The best estimate for the earlier australopithecines (which would be the latest possible human-chimp divergence time) was about 3 mya [!million years ago]; the oldest would have to be substantially less than 10 mya (otherwise the time scale for earlier divergences among primates would become terribly distorted).
By the same token, the Y-chromosome date for the beginning of racial differentiation in Homo sapiens cannot reasonably precede the exodus out of Africa, nor can it be more recent than, for example, perhaps twice the time of the Amerindians in the New World, or about 25,000 years ago. At this point, people who know this field are likely to raise the case of native Australians, who scientists believe have ben there for atleast 40,000 and perhaps as much as 60,000 years. It is also known, for certain, that recent Australians are not an out-group to all other human populations. Thus, if they have been separated from the latter for 40,000-60,000 years, the time of most recent common ancestry for the latter must be much greater. What is going on here? The likely answer is that those 40,000- to 60,000-year-old Australians have nothing to do with Australians with whom other people are familiar. First, the degree of known linguistic diversity in Australia need not have taken more than about 10,000 years to evolve. Second, there is no cultural (archaeological) continuity between sites more than 10,000 years of age and those less old. Third, those less than 6,000 years old seem to form a single cultural complex (including dingoes) that is intrusive. Last, the amount of morphological diversity among recent Australians (discussed later) is very small and does not increase much when Tasmanians and other Melanesians are included in the comparisons. Thus, we would not look for great age for determining antiquity of branching among the three groups...

...For purposes of this discussion, the trees presented in the two papers published in 2000 are congruent, showing common mtDNA and Y-chromosome trees with three lineages deriving from a common ancestor in each. Two of those could each be termed "old African"; that is, they contain only Africans, whereas most Africans and non-Africans for each molecule belong to a third. It is the third lineage that was present in the Homo population that evolved some adaptation to give it an ultimate advantage over all other Homo groups around at the time, colonizing Africa and the rest of the habitable world and making extinct any other populations. The question then becomes "what ultimate advantage?"
And the dates?
The calculation is still crude, but in the range of 40,000-50,000 years ago for the later out-of-Africa Eve.

SuuT
Sunday, January 14th, 2007, 02:12 AM
I just question the amount of time that is proposed as being enough to account for the amount of phenotypic (and even genotypic) variation...


From "Race - The Reality Of Human Differences", by Sarich and Miele:

The work of Sarich and Miele is actually what I was thinking of in my parenthetic remark (above), but it conflics - in a big way - with something else I have read that is more recent that I can't for the life of me remember - and its driving me nuts: I've been trying to remember where I saw it for most of this day (does any one know of this conflicting research?).

At any rate, let's assume the dating correct - that takes care of the genotypic variation. But what of the phenotypic variation present in modern populations!? I suppose it's possible, but it just doesn't seem like enough time for adaptive pressures, random mutation, and sexual selection to produce a Hallstatt in one area, and an Indonesian pygmy in another...

ladybright
Monday, January 15th, 2007, 05:21 PM
I had not noticed that this article was already posted in this thread. http://forums.skadi.net/spread_modern_humans_occurred_later_than _thought-t88124.html?p=740058#post740058If possible could this be deleted or moved there.


Humans migrated to Russia earlier than previously thought.

Fossil skull, artifact, help date human migration

By Maggie Fox, Health and Science Editor Thu Jan 11, 3:35 PM ET

WASHINGTON (Reuters) - An ancient skull from South Africa and carved tools and ornaments from Russia paint a rare picture of the time when modern humans migrated out of Africa to colonize Europe, researchers reported on Thursday.

The two reports in the journal Science link the far reaches of Europe to southernmost Africa across a short time span of 36,000 years ago to 45,000 years ago.

"The big surprise here is the very early presence of modern humans in one of the coldest, driest places in Europe," said John Hoffecker, of the University of Colorado-Boulder's Institute of Arctic and Alpine Research.

"It (Russia) is one of the last places we would have expected people from Africa to occupy first," Hoffecker said in a statement.

Scientists generally agree that modern humans spread out of Africa starting about 50,000 years ago, quickly establishing Stone Age cultures throughout Europe, Asia and Australia.

But there is a big gap in the evidence until about 30,000 years ago.

Ted Goebel of the Center for the Study of the First Americans at Texas A&M University said the two studies open a window into this mysterious period.

"Current interpretations of the human fossil record indicate that fully modern humans emerged in sub-Saharan Africa by 195,000 years ago," Goebel wrote in a commentary published in Science.

"By 35,000 years ago, modern humans thrived at opposite ends of Eurasia, from France to island southeast Asia and even Australia. How they colonized these and other drastically different environments during the intervening 160,000 years is one of the greatest untold stories in the history of humankind."

Very little hard evidence has been found linking early modern humans in Africa to these dispersed cultures. A less popular theory holds that modern humans evolved independently in Africa and Europe, Asia and elsewhere from Homo erectus, which had migrated much earlier.

OLD SKULL

For one of the studies, Frederick Grine of Stony Brook University in New York and an international group of colleagues re-examined a skull discovered in 1952 near Hofmeyr, South Africa.

It looked much more modern than other African skulls but it had been hard to date. The researchers used a combination of advanced optical and uranium methods to date the skull to about 36,000 years ago.

This was key, because few human fossils have been found in sub-Saharan Africa that date to between 70,000 and 15,000 years ago. Plenty of sophisticated stone and bone tools and artwork can be found, and fossils have been found in northern Africa and nearby areas of Asia and Europe -- but little from the birthplace of humanity itself.

"Here is the first skull of an adult modern human from sub-Saharan Africa that dates to the critical period, and one that can speak to the relationship of early moderns from Africa and Europe," Goebel wrote.

Hoffecker's Russia team lacks a skull, but the researchers have other evidence placing humans there at a crucial gap in time.

They, along with the Russian Academy of Sciences, reported on human teeth, tools, beads, carved ivory and other artifacts dug up at the Kostenki archeological site on the Don River in Russia, about 250 miles south of Moscow.

They date these artifacts to 45,000 to 42,000 years ago, an age similar to other items found in Western Europe.

One carved piece of mammoth ivory may be the unfinished head of a small human figurine. "If confirmed, it will be the oldest example of figurative art ever discovered," Hoffecker said.

Haldís
Tuesday, January 16th, 2007, 04:04 AM
An archaeological find in Russia has shed light on the migration of modern humans into Europe.

Artefacts uncovered at the Kostenki site, south of Moscow, suggest modern humans were at this spot about 45,000 years ago.

The first moderns may have entered Europe through a different route than was previously thought, the international team reports.

The research is published in the journal Science.

“Until now, it appeared as though the earliest presence of modern humans in Europe was in south central Europe, in places like Bulgaria and Greece,” explained John Hoffecker, author on the paper and a research scientist at the University of Colorado at Boulder, US.

“This reflects an entry from the Levant (eastern shores of the Mediterranean) just before 44,000 years ago.”

Missing Neanderthals

But the team believes it has now found an alternative and possibly earlier entry route into the continent.

The researchers examined tools, personal ornaments and carved ivory discovered under a layer of ancient volcanic ash at the site, which lies along the Don River.

The artefacts most likely belonged to modern humans and dated to about as early as 45,000 years ago, said Professor Hoffecker. However they were dissimilar to artefacts found at the other European sites, he added.

“This suggests we have a not very closely related group of people at Kostenki, suggesting at the very least that we have an alternate route for modern humans into Europe—perhaps this being the earliest one,” he told the BBC News website.

Professor Hoffecker said he was surprised to have found such early evidence of modern humans at Kostenki.

“It is arguably the coolest and driest part of mid-latitude Europe. It is the last place we would expect to see them first,” he added.

A possible reason to migrate to these harsher conditions may have been the lack of Neanderthals present in this area at this time.

“The absence of Neanderthals meant there were no competitors to deal with for resources,” Professor Hoffecker said.

Possible routes

Fossil records suggest modern humans emerged in sub-Saharan Africa about 200,000 years ago, but their dispersal is thought to have begun between 60,000 and 50,000 years ago.

The earliest evidence of modern humans appears in Australia, dating to about 50,000 years ago.

Professor Hoffecker said it was difficult to say exactly where the modern humans found in Kostenki would have come from.

One possible route, some researchers believe, is from western Asia via the Caucasus Mountains, which lie between the Caspian and Black Seas.

He added that modern humans might have migrated into central Asia, but then turned back on themselves to make the move into Europe.

Another paper, published in the same journal, reveals that a skull found in South Africa appears to represent an ancestor of the modern humans that eventually migrated to Europe and Asia.

Professor Chris Stringer of the department of palaeontology at the Natural History Museum, London, said: “These papers are interesting from an anthropological and archaeological point of view, and confirm some of the things we have thought on this subject.

“I think we will see increasing evidence of these ancestral modern people and their behaviour in western Asia, and at an even earlier date, in Africa.”

(http://news.bbc.co.uk/2/hi/science/nature/6253121.stm) http://news.bbc.co.uk/2/hi/science/nature/6253121.stm