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Danismyname wrote:
"FACT & TESTABLE : Mutations : DNA sequence changing almost always for the worse, and occasionally nuetral. I can't think of any observed that has been a positive mutation so if anyone has a reference please post."

A mutation having a positive effect (or negative or neutral for that matter) is a value judgement and one that can only be determined after-the-fact based upon the judgement of the observer.

From the standpoint of the AIDS virus its mutations have been very positive. TB too would agree that its mutations have been positive. A human lifetime is far too short to make this type of judgement about ourselves. But I might point out that 10,000 years ago not one of us had the capacity to grasp algebra ... today we can. Is that the result of a positive change in brain structure? Might well be. Perhaps we will know some day.

Danismyname wrote:
"There are a few other examples in modern things that evolution can't explain"

Too bad you didn't do what you said you wished to do: "add a little bit of objective ideas." There is nothing objective about your agenda.

Well that and you are incorrect. Evolution can explain everything you mentioned: Everything. The fact that you haven't studied the subject or can't grasp it, or that science continues to make progress and makes smaller the areas of darkness in which you dwell is not an issue.

You can still bury your head in the sand if you wish. But the desert is getting smaller and smaller with each passing day. Ignorance is NOT bliss.


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Danismyname would like someone to explain why we don't see species forming before our eyes. The short answer is that it takes a long time. Just confining ourselves to the subject of the original posting which deals with the evolution of H. erectus from some Australopithecus species:

The article shows that change was fairly slow, seems it took a million years, from 2.5 to 1.5 million years ago. A single small group of apes did not wake up one morning and suddenly find themselves to be human. It's not like becoming a rock star.

I remember finding an article in Nature vol. 441, no. 7097, 17th May 2006, entitled "Genetic evidence for complex speciation of humans and chimpanzees". Unfortunately I cannot find the full article on the net again. However you should be able to find at least a summary somewhere if you type in the above information in your search engine. In it the authors suggest the earlier split between apes and humans took three and a half million years, from 7.5 million years ago to 4 million years ago. In other words all the time from Sahelanthropus to Australopithecus. The divergence involved several periods of back hybridising.

Lets concede for a moment that all humans have evolved from a single human, a couple or even a small group. How can we account for the regional variation of modern humans without falling back on some form of evolution? We know that nearly all species vary over their geographic range. Sometimes the extremes are classified as separate species. Do horses, donkeys and zebras for example come from a common ancestor? In spite of myths the hybrid between a male horse and a female donkey are not always sterile. It's just the hybrid is useless to us humans.

Hope that clears up your puzzlement

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"There are a few other examples in modern things that evolution can't explain (or at least no reason for there being) that I'll find articles later and post later (as in tommorow) since I need to wake up in a few hours to go to work, I don't have time now."

Uh...no. There are "modern things" that it is ALLEGED that evolution can't explain. Creationists have a long history of falsely claiming that certain esoteric facts "couldn't possibly be explained by evolution."

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Evolution can even explain those that cling desperately to fairy tales and that is a huge accomplishment.


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Well first, I never asked for an explanation of why we don't see speciation. I know why we don't. I asked if someone had a reference off the top of their head because I wasn't sure if there was a documented and observed case over several dozen generations...

Second, how is pointing out that since the oldest fossils we have are either bacteria or algea, some 2.5-3 billion years old, in rock that paleontologists are debating how some formed. There is nothing to show the transition between single and multi-celled life reason to say that it is explainable. Scientific laws explain what we can see and test. Theories are educated guesses, and by educated I do mean well informed, which evolution is one of them. We have not seen a transition from multi to single celled life or from plant/bacteria to animal, or asexual to sexual reproduction or other such things. Because of this, and this is objective, modern fossils of these old lifeforms can not be the only way that evolution explains how all life evolved. The only thing they show is that there was life, and the shape of it, nothing else.

Thrid, Ignorance is not Bliss. When you claim something as undisputed fact when it isn't, there are problems. Evolutionary theory is used as a basis to make educated speculations on how all life arised, but all they are are speculations.

I think I should say this as the closer. Evolution is much much more plausible than creationism. I like how evolution does make plausible claims on a lot of things, but what I don't like is when people shout "It's fact and 100% proven" when it is not. So when arguments turn into you're wrong because evolution is right, I usually like to bring it back to a little more objectivity, since well that is what Science is, objectivity.

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There are examples of speciation at http://talkorgins.org/

Evolution is a fact. In science there is no such thing as an undisputable fact. However, evolution is as much a fact as the existence of hydrogen. Nobody has ever seen a hydrogen atom, but we don't teach them in school as "hypothetical" or "merely theoretical."

There are things that aren't explained yet. Every science has things that are unexplained - questions that haven't yet been answered. The theory of gravitation, however, is not mere speculation just because, as R. Feynman writes in Vol 1 of his "Essays on Physics", there is no mechanism for it. (Maybe there *IS* a mechanism by now, but there wasn't when he wrote it and still gravitation wasn't taught as "mere" theory.)

Fact does not mean "100% proven," at least not in the scientific parlance.

There's a lot more to say, but it's 1:30 am and I have to work tomorrow. If you honestly believe that evolution is more plausible than creationism, then you've probably done at least a little homework.

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Quote:
Originally posted by Mike Kremer:
Well I've Never really believed in the "Out of Africa Theory" anyway.
This seems more plausible...but its a very long article. From this weeks 'New Scientist' July 1st.
START
THE archaeological excavations at Dmanisi, in the Republic of Georgia, are a glorious exception to the rule that if you are in a hole, you should stop digging. What began as the excavation of a medieval town has turned into a pivotal site for our understanding of human evolution. So far, palaeoarchaeologists working there have unearthed five ancestral human skulls and other remains: the individuals they represent are now the central characters in a story whose plot is poised to undergo a major twist.

The story is known as Out of Africa. It tells of Africa as the centre of evolutionary innovation in our ancestors, and the springboard from which some of these hominins struck out into other continents. There are two main parts to the tale. The most familiar one charts the evolution of our own species in Africa around 200,000 years ago, and the subsequent migration of these modern humans throughout the world. The less well known part of the story concerns the first migration of our ancestors out of Africa, more than 1 million years earlier. It is this part of the story that is now being challenged for the first time. Last December, Nature ran a provocative critique by Robin Dennell of the University of Sheffield, UK, and Wil Roebroeks of Leiden University, the Netherlands, that concluded: "Most probably, we are on the threshold of a profound transformation of our understanding of early hominin evolution."

The "Out of Africa 1" story begins more than 2 million years ago when small upright African apes, known as australopithecines, start evolving into large and recognisably human creatures - the first members of our own genus, Homo. Eventually one of these, Homo erectus, strikes out to conquer Eurasia. At the heart of the tale of this first transcontinental migration lies the assumption that what made us human also propelled us out across the rest of the planet. This idea has a powerful romantic appeal, suggesting that exploration and settlement are primordial and defining human instincts. H. erectus had "a typically insatiable human wanderlust", according to palaeoanthropologist Ian Tattersall of the American Museum of Natural History in New York. What enabled these beings to satisfy the urge to boldly go was their package of characteristically human traits that distinguished them from the australopithecines: longer limbs, increased body and brain size, an omnivorous diet and the use of stone tools.

Until quite recently, all the evidence seemed to support this view and version of events. The earliest remains of H. erectus in Africa are about 1.8 million years old. At first these beings seem to have produced only simple flaked stone tools, but around 1.5 million years ago these are joined in the archaeological record by teardrop-shaped hand axes, suggesting that their creators had reached a new level of sophistication. In addition, the various hominin fossils found in east Asia over the past century (see "The shifting spotlight") had been dated at a million years old at most. The timing of all this seemed to attest to the emergence of H. erectus in Africa, its growing ingenuity there and then gradual spread eastward.

In the past decade, however, this sequence has begun to unravel. Fossils of H. erectus found at the Indonesian sites of Sangiran and Mojokerto are now believed to be over 1.5 million years old - possibly as much as 1.8 million years old. Those at Dmanisi have been dated at 1.7 million years or more. With these startlingly early dates from both ends of Asia it looks as though H. erectus materialised almost simultaneously in Africa, east Asia and a point in between. What's more, hand axes have proved to be red herrings. The stone tools associated with the migrant populations are no technological advance on the first ones to appear in the archaeological record, half a million years previously (see "Tooled up and ready to go"). As for brain size: with an adult average of about 700 cubic centimetres these colonisers had the edge on australopithecines, whose brains were under half a litre, but they were at the bottom end of the H. erectus range, and had only about half the volume of a modern human brain. It looks as though increased intelligence was not a prerequisite for migration.

A still more radical challenge to the supposed role of superior cognitive abilities in the dispersal of hominins comes from a mid-1990s fossil discovery that Dennell considers one of the most important of the past two decades. Australopithecine fossils had hitherto been found in the Great Rift Valley of eastern Africa and in the south of the continent. Then one turned up in Chad, in the middle of the continent, 2500 kilometres away from the Rift Valley. If australopithecines were able to colonise that region between 3 and 3.5 million years ago, argues Dennell, there is no reason why they should have stopped at the Red Sea. Ancient hominins would not have distinguished between Africa and Asia, and neither should we, he and Roebroeks argue. Those australopithecines in Chad date from an era when grasslands stretched from northern Africa to eastern Asia. Other animals moved freely across this landscape, so why not hominins? "If you were a herbivore that took grass seriously," Dennell remarks, "you could munch your way all across south-west Asia to northern China." He and Roebroeks suggest that we should re-imagine this vast transcontinental band of grass as a zone throughout which our ancestors also roamed. Dennell has dubbed it "Savannahstan".

The savannahs were the product of global cooling, which dried out moist woodlands, shifting the balance to grass. Over millions of years, the global climate gradually cooled, but there were also times when conditions altered quite abruptly. These shifts rearranged the fauna - species vanished, new species emerged. One of these climatic pulses occurred around 2.5 million years ago. In the Arctic, ice sheets spread. In eastern Africa, forest-adapted antelopes were replaced by those suited to savannah. New, robust australopithecines appeared, as did somewhat larger-brained hominins, Homo habilis, the first members of the Homo genus, and we also find the earliest known stone tools.

In a bold challenge to the conventional story, Dennell argues that hominins migrated out of Africa before H. erectus even evolved, and long before the dates of the oldest known hominin fossils in Asia. These first migrants were either australopithecines or H. habilis - he, like some prominent palaeoanthropologists, regards these two as much the same kind of creatures. For evidence that small stature was no obstacle to dispersal he points to the Dmanisi hominins. Not only do their brain sizes fit within the H. habilis range, evidence from a femur and a tibia, as yet unpublished, indicates that one of them may have weighed only about 54 kilograms and stood just 1.4 metres tall. Although the stature of the individuals at Sangiran and Mojokerto is unknown, hominins clearly did not need long legs to stride out of Africa.

?In a bold challenge to the conventional story, some argue that hominins migrated out of Africa before H. erectus evolved?What's more, Dennell has the makings of a story set in Savannahstan that could explain a key mystery of human evolution - what spurred the evolution of H. erectus itself. While H. habilis seems to have evolved in response to the cold snap around 2.5 million years ago, there is no such climate change in Africa coinciding with the emergence of the earliest known examples of H. erectus, around 1.8 million years ago. Nor does H. erectus have any clearly identifiable immediate predecessors. "Not for nothing has it been described as a hominin 'without an ancestor, without a clear past'," observe Dennell and Roebroeks.

Dennell's solution to the problem is beguilingly simple: perhaps we have been looking in the wrong place. "Maybe the Rift Valley was a cul-de-sac," Dennell suggests. Tongue in cheek perhaps, but the remark conveys his strong conviction that the importance of Asia has been unfairly neglected. At around the time H. erectus emerged some 1.8 million years ago, selective pressures to evolve would have been greater in Asia than in Africa, he argues. Traces of the global cooling pulse starting around 2.5 million years ago have been detected in the soils of China's Loess Plateau.

Beneath the silty loess are layers of red clay, which appear to have been blown there by westerly winds before the cooling began. Above these, the particles of loess decrease in size from north to south, indicating that they were deposited by northerly winds, the heavier particles falling to the ground first. So it appears that the winds changed when the climate cooled. This would have brought monsoons and polarised the years into seasons, with summers becoming increasingly arid over subsequent millennia, causing the grasslands to expand. Asia was the core of this process and Africa was peripheral, according to Dennell.

In this perspective the Dmanisi hominins may represent a missing link in the evolution of H. erectus, responding to climatic pressures but still retaining much in common with H. habilis. Australopithecines were adapted to open spaces in woodlands, ranging around relatively small areas, living off plants, seeds, small mammals and perhaps carcasses. As these open spaces expanded into savannah, the Dmanisi hominins would have faced pressures to evolve more human-like traits, increasing the distances over which they ranged, and turning more to animals as a source of food.

Dennell even goes so far as to suggest that the Dmanisi hominins might be ancestors of the later H. erectus in Africa. The most celebrated representative there is the 1.6-million-year-old "Turkana Boy". His tall stature, long limbs and body proportions epitomise adaptation to a hot, dry climate. In other words, African H. erectus might have Asian roots. If this is the case, Out of Africa 1 is a crucial part of the story of our own evolution, since H. erectus is generally thought to be a direct ancestor of modern humans.

?African H. erectus might have had Asian roots, adding a crucial twist to the story of our own evolution?Since Dennell and Roebroeks wrote their Nature review, American and Georgian researchers studying the Dmanisi finds have published a paper that points in a similar direction (Journal of Human Evolution, vol 50(2), p 115). Suggesting the finds be classed as Homo erectus georgicus, Philip Rightmire of Binghamton University, New York, and his colleagues conclude that Dmanisi may be "close to the stem from which H. erectus evolved". They also point to the possibility that the Dmanisi population's ancestors were H. habilis emigrants from Africa, and that the dates do not rule out the possibility that H. erectus evolved in Asia. "For me, the evidence from Dmanisi is critical," says Rightmire. "It seems to me that such a population could well be ancestral to H. erectus in Africa and also to H. erectus in the Far East." But he anticipates that rewriting the origin and dispersal of H. erectus will be a slow process. "We're not likely to see a major breakthrough immediately."

Further research that broadly chimes with Dennell and Roebroeks's arguments comes from Alan Templeton of Washington University, St Louis (Yearbook of Physical Anthropology, vol 48, p 33). By comparing clusters of DNA that vary between individuals and tend to be inherited together, geneticists can identify when particular mutations arose, and use these to map relationships within or between species. Until a few years ago, they had to rely on DNA from mitochondria or sex chromosomes, but it is now becoming possible to increase the resolution of such maps by using data from the rest of the genome. Comparing 25 DNA regions in the genomes of people from across the world, Templeton found evidence for an expansion out of Africa around 1.9 million years ago, and that gene flow between African and Eurasian populations - in both directions - was established by 1.5 million years ago. Not only do these findings suggest that migration began earlier than previously thought, it also looks as though hominins were moving back and forth between Eurasia and Africa.

"The hypotheses Dennell and Roebroeks present are testable with molecular genetic data," Templeton says, "so I think that the prospects for testing some of their alternatives to 'Out of Africa 1' will be excellent in the near future." Only four years ago, when he first conducted an analysis of this kind, there were insufficient results for him to detect any expansion out of Africa between 1 and 3 million years ago. Increasingly, however, researchers looking for genetic variation among individuals are also recording their geographical origins - just the information Templeton needs to do his analysis. "I anticipate greater and greater statistical resolution of these older events in human evolutionary history," he says. "Genetics will play an increasing and important role in testing their ideas in conjunction with new fossil and archaeological discoveries."

For Dennell, however, the objects in the ground are what matters. He is keen to look for hominin remains in Asia to balance the generous legacies of the Rift Valley and southern Africa. Unfortunately, the countries he most wants to search - Saudi Arabia, Iran, Afghanistan - read like a list of places not to visit these days. A site in Pakistan where he found stone tools in the 1980s dating from 1.9 million years ago is also now off limits because of the political turbulence that has spread across the region. It seems that Asia will not give up its secrets easily, but Dennell is convinced that in this case, absence of evidence is not evidence of absence. The search may prove difficult but the rewards are potentially enormous, amounting to nothing less than the rewriting of human prehistory.

From issue 2558 of New Scientist magazine, 01 July 2006, page 34
***
THERE ARE MANY FURTHER Pictures and comments by others. But I have not included those to save space. Since the full article will be put on the Net, by New Scientist next week.


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Simply put: Africa was not connected to europe until quite late in human history, so it could not be the origin. Enough said.

Quote:
Originally posted by Mike Kremer:
Well I've Never really believed in the "Out of Africa Theory" anyway.
This seems more plausible...but its a very long article. From this weeks 'New Scientist' July 1st.
START
THE archaeological excavations at Dmanisi, in the Republic of Georgia, are a glorious exception to the rule that if you are in a hole, you should stop digging. What began as the excavation of a medieval town has turned into a pivotal site for our understanding of human evolution. So far, palaeoarchaeologists working there have unearthed five ancestral human skulls and other remains: the individuals they represent are now the central characters in a story whose plot is poised to undergo a major twist.

The story is known as Out of Africa. It tells of Africa as the centre of evolutionary innovation in our ancestors, and the springboard from which some of these hominins struck out into other continents. There are two main parts to the tale. The most familiar one charts the evolution of our own species in Africa around 200,000 years ago, and the subsequent migration of these modern humans throughout the world. The less well known part of the story concerns the first migration of our ancestors out of Africa, more than 1 million years earlier. It is this part of the story that is now being challenged for the first time. Last December, Nature ran a provocative critique by Robin Dennell of the University of Sheffield, UK, and Wil Roebroeks of Leiden University, the Netherlands, that concluded: "Most probably, we are on the threshold of a profound transformation of our understanding of early hominin evolution."

The "Out of Africa 1" story begins more than 2 million years ago when small upright African apes, known as australopithecines, start evolving into large and recognisably human creatures - the first members of our own genus, Homo. Eventually one of these, Homo erectus, strikes out to conquer Eurasia. At the heart of the tale of this first transcontinental migration lies the assumption that what made us human also propelled us out across the rest of the planet. This idea has a powerful romantic appeal, suggesting that exploration and settlement are primordial and defining human instincts. H. erectus had "a typically insatiable human wanderlust", according to palaeoanthropologist Ian Tattersall of the American Museum of Natural History in New York. What enabled these beings to satisfy the urge to boldly go was their package of characteristically human traits that distinguished them from the australopithecines: longer limbs, increased body and brain size, an omnivorous diet and the use of stone tools.

Until quite recently, all the evidence seemed to support this view and version of events. The earliest remains of H. erectus in Africa are about 1.8 million years old. At first these beings seem to have produced only simple flaked stone tools, but around 1.5 million years ago these are joined in the archaeological record by teardrop-shaped hand axes, suggesting that their creators had reached a new level of sophistication. In addition, the various hominin fossils found in east Asia over the past century (see "The shifting spotlight") had been dated at a million years old at most. The timing of all this seemed to attest to the emergence of H. erectus in Africa, its growing ingenuity there and then gradual spread eastward.

In the past decade, however, this sequence has begun to unravel. Fossils of H. erectus found at the Indonesian sites of Sangiran and Mojokerto are now believed to be over 1.5 million years old - possibly as much as 1.8 million years old. Those at Dmanisi have been dated at 1.7 million years or more. With these startlingly early dates from both ends of Asia it looks as though H. erectus materialised almost simultaneously in Africa, east Asia and a point in between. What's more, hand axes have proved to be red herrings. The stone tools associated with the migrant populations are no technological advance on the first ones to appear in the archaeological record, half a million years previously (see "Tooled up and ready to go"). As for brain size: with an adult average of about 700 cubic centimetres these colonisers had the edge on australopithecines, whose brains were under half a litre, but they were at the bottom end of the H. erectus range, and had only about half the volume of a modern human brain. It looks as though increased intelligence was not a prerequisite for migration.

A still more radical challenge to the supposed role of superior cognitive abilities in the dispersal of hominins comes from a mid-1990s fossil discovery that Dennell considers one of the most important of the past two decades. Australopithecine fossils had hitherto been found in the Great Rift Valley of eastern Africa and in the south of the continent. Then one turned up in Chad, in the middle of the continent, 2500 kilometres away from the Rift Valley. If australopithecines were able to colonise that region between 3 and 3.5 million years ago, argues Dennell, there is no reason why they should have stopped at the Red Sea. Ancient hominins would not have distinguished between Africa and Asia, and neither should we, he and Roebroeks argue. Those australopithecines in Chad date from an era when grasslands stretched from northern Africa to eastern Asia. Other animals moved freely across this landscape, so why not hominins? "If you were a herbivore that took grass seriously," Dennell remarks, "you could munch your way all across south-west Asia to northern China." He and Roebroeks suggest that we should re-imagine this vast transcontinental band of grass as a zone throughout which our ancestors also roamed. Dennell has dubbed it "Savannahstan".

The savannahs were the product of global cooling, which dried out moist woodlands, shifting the balance to grass. Over millions of years, the global climate gradually cooled, but there were also times when conditions altered quite abruptly. These shifts rearranged the fauna - species vanished, new species emerged. One of these climatic pulses occurred around 2.5 million years ago. In the Arctic, ice sheets spread. In eastern Africa, forest-adapted antelopes were replaced by those suited to savannah. New, robust australopithecines appeared, as did somewhat larger-brained hominins, Homo habilis, the first members of the Homo genus, and we also find the earliest known stone tools.

In a bold challenge to the conventional story, Dennell argues that hominins migrated out of Africa before H. erectus even evolved, and long before the dates of the oldest known hominin fossils in Asia. These first migrants were either australopithecines or H. habilis - he, like some prominent palaeoanthropologists, regards these two as much the same kind of creatures. For evidence that small stature was no obstacle to dispersal he points to the Dmanisi hominins. Not only do their brain sizes fit within the H. habilis range, evidence from a femur and a tibia, as yet unpublished, indicates that one of them may have weighed only about 54 kilograms and stood just 1.4 metres tall. Although the stature of the individuals at Sangiran and Mojokerto is unknown, hominins clearly did not need long legs to stride out of Africa.

?In a bold challenge to the conventional story, some argue that hominins migrated out of Africa before H. erectus evolved?What's more, Dennell has the makings of a story set in Savannahstan that could explain a key mystery of human evolution - what spurred the evolution of H. erectus itself. While H. habilis seems to have evolved in response to the cold snap around 2.5 million years ago, there is no such climate change in Africa coinciding with the emergence of the earliest known examples of H. erectus, around 1.8 million years ago. Nor does H. erectus have any clearly identifiable immediate predecessors. "Not for nothing has it been described as a hominin 'without an ancestor, without a clear past'," observe Dennell and Roebroeks.

Dennell's solution to the problem is beguilingly simple: perhaps we have been looking in the wrong place. "Maybe the Rift Valley was a cul-de-sac," Dennell suggests. Tongue in cheek perhaps, but the remark conveys his strong conviction that the importance of Asia has been unfairly neglected. At around the time H. erectus emerged some 1.8 million years ago, selective pressures to evolve would have been greater in Asia than in Africa, he argues. Traces of the global cooling pulse starting around 2.5 million years ago have been detected in the soils of China's Loess Plateau.

Beneath the silty loess are layers of red clay, which appear to have been blown there by westerly winds before the cooling began. Above these, the particles of loess decrease in size from north to south, indicating that they were deposited by northerly winds, the heavier particles falling to the ground first. So it appears that the winds changed when the climate cooled. This would have brought monsoons and polarised the years into seasons, with summers becoming increasingly arid over subsequent millennia, causing the grasslands to expand. Asia was the core of this process and Africa was peripheral, according to Dennell.

In this perspective the Dmanisi hominins may represent a missing link in the evolution of H. erectus, responding to climatic pressures but still retaining much in common with H. habilis. Australopithecines were adapted to open spaces in woodlands, ranging around relatively small areas, living off plants, seeds, small mammals and perhaps carcasses. As these open spaces expanded into savannah, the Dmanisi hominins would have faced pressures to evolve more human-like traits, increasing the distances over which they ranged, and turning more to animals as a source of food.

Dennell even goes so far as to suggest that the Dmanisi hominins might be ancestors of the later H. erectus in Africa. The most celebrated representative there is the 1.6-million-year-old "Turkana Boy". His tall stature, long limbs and body proportions epitomise adaptation to a hot, dry climate. In other words, African H. erectus might have Asian roots. If this is the case, Out of Africa 1 is a crucial part of the story of our own evolution, since H. erectus is generally thought to be a direct ancestor of modern humans.

?African H. erectus might have had Asian roots, adding a crucial twist to the story of our own evolution?Since Dennell and Roebroeks wrote their Nature review, American and Georgian researchers studying the Dmanisi finds have published a paper that points in a similar direction (Journal of Human Evolution, vol 50(2), p 115). Suggesting the finds be classed as Homo erectus georgicus, Philip Rightmire of Binghamton University, New York, and his colleagues conclude that Dmanisi may be "close to the stem from which H. erectus evolved". They also point to the possibility that the Dmanisi population's ancestors were H. habilis emigrants from Africa, and that the dates do not rule out the possibility that H. erectus evolved in Asia. "For me, the evidence from Dmanisi is critical," says Rightmire. "It seems to me that such a population could well be ancestral to H. erectus in Africa and also to H. erectus in the Far East." But he anticipates that rewriting the origin and dispersal of H. erectus will be a slow process. "We're not likely to see a major breakthrough immediately."

Further research that broadly chimes with Dennell and Roebroeks's arguments comes from Alan Templeton of Washington University, St Louis (Yearbook of Physical Anthropology, vol 48, p 33). By comparing clusters of DNA that vary between individuals and tend to be inherited together, geneticists can identify when particular mutations arose, and use these to map relationships within or between species. Until a few years ago, they had to rely on DNA from mitochondria or sex chromosomes, but it is now becoming possible to increase the resolution of such maps by using data from the rest of the genome. Comparing 25 DNA regions in the genomes of people from across the world, Templeton found evidence for an expansion out of Africa around 1.9 million years ago, and that gene flow between African and Eurasian populations - in both directions - was established by 1.5 million years ago. Not only do these findings suggest that migration began earlier than previously thought, it also looks as though hominins were moving back and forth between Eurasia and Africa.

"The hypotheses Dennell and Roebroeks present are testable with molecular genetic data," Templeton says, "so I think that the prospects for testing some of their alternatives to 'Out of Africa 1' will be excellent in the near future." Only four years ago, when he first conducted an analysis of this kind, there were insufficient results for him to detect any expansion out of Africa between 1 and 3 million years ago. Increasingly, however, researchers looking for genetic variation among individuals are also recording their geographical origins - just the information Templeton needs to do his analysis. "I anticipate greater and greater statistical resolution of these older events in human evolutionary history," he says. "Genetics will play an increasing and important role in testing their ideas in conjunction with new fossil and archaeological discoveries."

For Dennell, however, the objects in the ground are what matters. He is keen to look for hominin remains in Asia to balance the generous legacies of the Rift Valley and southern Africa. Unfortunately, the countries he most wants to search - Saudi Arabia, Iran, Afghanistan - read like a list of places not to visit these days. A site in Pakistan where he found stone tools in the 1980s dating from 1.9 million years ago is also now off limits because of the political turbulence that has spread across the region. It seems that Asia will not give up its secrets easily, but Dennell is convinced that in this case, absence of evidence is not evidence of absence. The search may prove difficult but the rewards are potentially enormous, amounting to nothing less than the rewriting of human prehistory.

From issue 2558 of New Scientist magazine, 01 July 2006, page 34
***
THERE ARE MANY FURTHER Pictures and comments by others. But I have not included those to save space. Since the full article will be put on the Net, by New Scientist next week.


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Dear Frog:
I ignored everything you copied as I am more than capable of following a link.

In the future please don't waste our time or our bandwidth.

If you have something to say ... use your own brain and your own words of which I don't see a single one.

Thank you.


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Frog in my head.

What is your point exactly? Europe has been connected to Africa via the Middle East for the whole of human existence. But I still fail to see the relevance of this. Anyway no problem for ancient humans to get to Europe. Or for any other animals that occupied the appropriate environment.

I suppose it was worthwhile our reading the article again twice. I actually have seen the original complete with pretty pictures.

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I don't want to seem pedantic but the term 'Out of Africa' is generally accepted as referring to the origin and spread (from Africa, obviously) of modern humans ie Homo sapiens whereas this article is referring to Homo erectus.


Eduardo
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Sorry Eduardo. I should have done this the other night. You wrote:

I don't want to seem pedantic but the term 'Out of Africa' is generally accepted as referring to the origin and spread (from Africa, obviously) of modern humans ie Homo sapiens whereas this article is referring to Homo erectus.

Quite correct. But the original posting demonstrates that at least some of our evolution has happened as a result of gene flow, the movement of populations through regions already occupied by a variation of that species. It is therefore fair to say that the mitochondrial DNA evidence used as support for the evolution of "modern" humans was the result of a similar process. Another point made in the original posting is that "each gene has its own evolutionary history". This quote is actually from a paper "Ancestral Asian sources of New World Y-chromosome founder haplotypes", Karafet et al American Journal of Human Genetics, 64: 817-831. Geneticsts have long accepted it though.

The mtDNA evidence is best regarded as just one more human gene. There may have been selection for people carrying this gene but for various reasons it's more likely to be cultural rather than genetic. Besides if you can provide me with any evidence for when this modern "Out of Africa" occurred let me know. It's very imprecise. Anywhere between a hundred thousand years ago till 50,000.

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Hi Terry,

I wasn't questioning the validity of the article in any way, merely trying to clear up an ambiguity of terminology.

PS I do not see this as a 'black vs white' issue (mmm, perhaps that could be better phrased given the subject). I have no doubt that some gene flow occurred, the question is how much.


Eduardo
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Eduardo, Thanks for the question. I'll see if I can get our heads around it.

Firstly the article mentions genes that show a point of origin within the human species going back over the last two million years. The first of these genes to be studied was mitochondrial DNA. This was because there is so much of it and it doesn't recombine. The results showed the mtDNA line split in two about 180,000 years ago. Allan Wilson (a New Zealnder, yay) jokingly called the common female ancestor Eve and immediately regretted it. Aha, the Bible is basically correct after all. What a relief. As a result the distinctiveness of mtEve's line has been greatly exaggerated. Try finding it in the fossils for example. Or any change in technology. No can do.

As the article points out Alan Templeton of Washington University has developed techniques from those used for mtDNA to look at single genes. PCR has allowed him to multiply the DNA strands and so supply is not a problem either. As he says in the article he has traced the regional origin of many of those genes.

How much interbreeding between mtEve's descendants from Africa and the original inhabitants in each region? I think the evidence shows: quite a bit.

The modern Asian type seems to have been developing by about 300,000 years ago. Also there are similarities between some early Australian fossils and Javan H. erectus. Many modern European skulls are closer to Neanderthal skulls than are Polynesian skulls.

Of course including Neanderthals in our species means the Bible falls to pieces again. We have to be cleverer than those Neanderthals. After all we replaced them. But did we? I think the evidence shows overwhelmingly that we did not. Unfortunately the complete proof for substantial hybridizing is long and complicated.

What do you think of that?

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My vote is that there are two reasons there are no more Neandertals.

1. We were better at genocide.
2. We were better at genocide.

Couldn't think of a third-reason.


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Terry, please don't get me started on the hybridisation issue, I had a barney about that on this very forum some time ago for daring to suggest that it was even possible. Using precisely this mtDNA is not the only gene argument.

If you know of any good online articles on this subject I would be very interested.

PS barney means fight or argument in my native south London tongue.

PPS I was in NZ a couple of years ago, Tauranga to be exact. Nice view from Maunganui.


Eduardo
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Quote:
Originally posted by DA Morgan:
My vote is that there are two reasons there are no more Neandertals.

1. We were better at genocide.
2. We were better at genocide.

Couldn't think of a third-reason.
from what ive read (please its been decades, so dont ask for links), man was better at hunting and gathering than the neadertals, so we starved him to death.


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Don't know of any sites but we have the evidence of hybrid cultures if not genetic hybrids. eg. Chatelperronian, Uluzzian and Szeletian. Should find something about them easily enough. How would the culture hybridize without at least social contact. Also the Portuguese skeleton that many people regard as a hybrid.

We also have modern evidence of hybrids between different-looking people. At least we do in New Zealand, perhaps less so in other countries. We always look at the world through the prism of our own upbringing.

There are many examples of hybrids between different species. Try following evolution of dabbling ducks online. There is nothing impossible about Neranderthal genes being with us still. If I come across any sites I'll let you know.

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dehammer wrote:
"man was better at hunting and gathering than the neadertals, so we starved him to death."

and

"please its been decades, so dont ask for links"

I went to google.com
I typed in "Nealdertal" and "hunters"

It really wasn't that hard. Though it did require moving the mouse and typeing in two words.

Ouch! My carpal tunnel is acting up again.

Seriously dehammer ... how can you be so lazy?


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I seriously doubt that you found the article i was refering too. it was long before apples computer came out, let alone the internet. Im glad that you found it of enough interest that you checked it out.


the more man learns, the more he realises, he really does not know anything.
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