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Neanderthals |
coldrum
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|  Posted 23-02-2010 at 11:45
Could Neanderthals live again?
Researchers are closer than ever to having a first draft of a complete sequence of the genome of a Neanderthal woman who lived some 30,000 years ago, and this means it may one day be possible to create a living person from the DNA sequence.
The Neanderthal woman died in the Vindija cave in what is now Croatia. Neanderthals are the nearest extinct relative of modern-day humans. Homo sapiens and Neanderthals coexisted for 5-7,000 years, but Neanderthals were gradually forced to retreat to the edges of what is now Europe. The fragments of DNA from the woman's bones were assembled using human and chimpanzee genomes as references. Researcher Gerald Irzyk said putting the fragments in order is difficult because at first it seems a random assemblage of the nucleotide bases, but there are patterns and motifs that are often specific to a group of organisms.
The project to map the genome began in 2005, and is run collaboratively by scientists at the Max Planck Institute in Leipzig, Germany and 454 Life Sciences at Branford, Connecticut. The work has been made possible by today’s powerful computers, which enable scientists to drastically cut the time and cost, but it has still faced many challenges largely through contamination and the breakdown and chemical changes in the biological material over time.
When an organism dies, enzymes break DNA into small fragments of only a few hundred base pairs or less. The DNA is also chemically changed over time, which can lead to incorrect interpretations of the sequence. Not only that, but over 90% of the DNA in the samples came from bacteria or other contaminants rather than the bone.
Creating body parts, organs, and even a complete living individual once the genome is completely sequenced would be difficult but is theoretically possible. The procedure would involve making possibly millions of changes to the DNA in a human stem cell to match the Neanderthal genetic sequence, but there remain problems because even if the Neanderthal genes could be recreated we do not know how they were expressed. Assuming it can be created, the stem cell with Neanderthal DNA would divide to produce a colony of cells that could then be instructed to become any type of cell in the body, theoretically including an entire individual.
Chief science officer of Advanced Cell Technology, Robert Lanza said in Archaeology magazine that “species such as cows and goats are now routinely cloned with few problems,” and while there are many more challenges in the case of cloning a Neanderthal, it possibly could be done. The ethics of such a move would be certain to spark a great deal of debate, and not just between paleoanthropologists.
Author of the Archaeology magazine article, Zach Zorich, who has been a keen follower of research on the Neanderthal genome, noted that if created, the Neanderthal would legally deserve the same human rights as we do.
It is likely to be quite some time before we need to deal with the ethical issues. Stephan Schuster, a geneticist from Pennsylvania State University, explained that the first draft of the genome will probably contain many errors due to the age of the sample and the contamination, and he calculates the DNA in five different samples of bone would have to be sequenced, and in all the genome would need to be sequenced 30 times before we could be confident of its accuracy.
Mapping the genome should allow scientists to answer questions about the relationship between us and Neanderthals, such as whether we interbred, and were separate species. It may also be useful in medical research.
http://www.physorg.com/news185091636.html
http://www.archaeology.org/1003/etc/neanderthals.html
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coldrum
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| Posted 23-02-2010 at 12:42
How a hobbit is rewriting the history of the human race
The discovery of the bones of tiny primitive people on an Indonesian island six years ago stunned scientists. Now, further research suggests that the little apemen, not Homo erectus, were the first to leave Africa and colonise other parts of the world, reports Robin McKie.
It remains one of the greatest human fossil discoveries of all time. The bones of a race of tiny primitive people, who used stone tools to hunt pony-sized elephants and battle huge Komodo dragons, were discovered on the Indonesian island of Flores in 2004.
The team of Australian researchers had been working in a vast limestone cavern, called Liang Bua, in one of the island's remotest areas, when one scientist ran his trowel against a piece of bone. Carefully the group began scraping away the brown clay in which pieces of a tiny skull, and a little lower jaw, were embedded.
This was not any old skull, they quickly realised. Although small, it had special characteristics. In particular, it had adult teeth. "This was no child, but a tiny adult; in fact, one of the smallest adult hominids ever found in the fossil record," says Mike Morwood, of Australia's University of Wollongong and a leader of the original Flores expedition team.
The pieces of bone were carefully wrapped in newspaper, packed in cardboard boxes and then cradled on the laps of scientists on their journey, by ferry and plane, back to Jakarta. Then the pieces of skull, as well as bones from other skeletons found in Liang Bua, were put together.
The end result caused consternation. These remains came from a species that turned out to be only three feet tall and had the brain the size of an orange. Yet it used quite sophisticated stone tools. And that was a real puzzle. How on earth could such individuals have made complex implements and survived for aeons on this remote part of the Malay archipelago?
Some simply dismissed the bones as the remains of deformed modern humans with diseases that had caused them to shrink: to them, they were just pathological oddities, it was alleged. Most researchers disagreed, however. The hobbits were the descendants of a race of far larger, ancient humans who had thrived around a million years ago. These people, known as Homo erectus, had become stranded on the island and then had shrunk in an evolutionary response to the island's limited resources.
That is odd enough. However, new evidence suggests the little folk of Flores may be even stranger in origin. According to a growing number of scientists, Homo floresiensis is probably a direct descendant of some of the first apemen to evolve on the African savannah three million years ago. These primitive hominids somehow travelled half a world from their probable birthplace in the Rift Valley to make their homes among the orangutans, giant turtles and rare birds of Indonesia before eventually reaching Flores.
It sounds improbable but the basic physical similarity between the two species is striking. Consider Lucy, the 3.2 million-year-old member of Australopithecus afarensis. She had a very small brain, primitive wrists, feet and teeth and was only one metre tall, but was still declared "the grandmother of humanity" after her discovery in Ethiopia in 1974. Crucially, analysis of Lucy's skeleton shows it has great similarities with the bones of H. floresiensis, although her species died out millions of years ago while the hobbits hung on in Flores until about 17,000 years ago. This latter figure is staggeringly close in terms of recent human evolution and indicates that long after the Neanderthals, our closest evolutionary relatives, had disappeared from the face of the Earth around 35,000 years ago, these tiny, distant relatives of Homo sapiens were still living on remote Flores.
The crucial point about this interpretation is that it explains why the Flores people had such minuscule proportions. They didn't shrink but were small from the start – because they came from a very ancient lineage of little apemen. They acquired no diseased deformities, nor did they evolve a smaller stature over time. They were, in essence, an anthropological relic and Flores was an evolutionary time capsule. In research that provides further support for this idea, scientists have recently dated some stone tools on Flores as being around 1.1 million years old, far older than had been previously supposed.
The possibility that a very primitive member of the genus Homo left Africa, roughly two million years ago, and that a descendant population persisted until only several thousand years ago, is one of the more provocative hypotheses to have emerged in anthropology during the past few years," David Strait of the University of Albany told Scientific American recently. This view is backed by Professor Chris Stringer of the Natural History Museum, London. "We are still grappling with what this discovery has done for our thinking and our conventional scenarios."
In addition, Mike Morwood says he has now uncovered stone tools on nearby Sulawesi. These could be almost two million years old, he believes, which suggests the whole region was populated by very ancient humans for a startlingly long part of human prehistory. "This is going to put the cat among the pigeons," Morwood says.
However, it is the hobbits' similarity to ancient African apemen that provides the most compelling evidence for their ancient origins. In the Journal of Human Evolution, a team led by Debbie Argue of the Australian National University, recently reported that analysis of H. floresiensis shows they most closely resemble apelike human ancestors that first appeared around 2.3 million years ago in Africa. In other words, their stock may be not quite as old as Lucy's but probably comes from a hominid, known as Homo habilis, that appeared on the evolutionary scene not long after Lucy's species disappeared. Homo habilis's features now seem to match, most closely, those of H. floresiensis.
Consider those hobbit feet, for example. The skeleton unearthed on Flores had a foot that was 20cm in length. This produces a ratio of 70 per cent when compared with the length of the hobbit's thigh bone. By contrast, men and women today have foot-to-thigh bone ratios of 55 per cent. The little folk of Flores had singularly short legs and long, flapper feet, very similar to those of African apemen, even though limbs like these would have made their long march from Africa to Flores a painful business.
Similarly, the hands of H. floresiensis were more like apes than those of evolved humans, their wrists possessing trapezoid bones that would have made the delicate art of stone tool-making very difficult. Their teeth show primitive traits while their brains were little bigger than those of chimpanzees, though CT scans of skull interiors suggest they may have had cognitive skills not possessed by apes.
Nevertheless, this little apeman, with poor physique, a chimp-sized brain and only a limited ability to make tools, now appears to have left Africa, travelled thousands of miles and somehow colonised part, if not all, of south-east Asia two million years ago.
Scientists had previously assumed only a far more advanced human ancestor, such as Homo erectus, was capable of undertaking that task and only managed to do so about a million years ago when our predecessors had evolved powerful physiques, a good gait and the beginnings of intellect. Without these, we would have got nowhere, it was implied.
Then along came little H. floresiensis which, quite simply, has "no business being there," says Morwood. And you can see what he means. Apart from the sheer improbability of a jumped-up ape travelling from Africa to Indonesia, there is the particular puzzle of how it got to Flores.
Primitive hominids were almost certainly incapable of sailing. So how did it arrive on the island in the first place? It is a puzzle, although Stringer believes the region's intense tectonic activity is significant. "After the Indian Ocean tsunami in 2004, people were found far out at sea clinging to rafts of vegetation. Things like that could have happened regularly in the past and people could have been swept out to sea and washed ashore on Flores. Alternatively, there could have been short-lived connections between now separate islands."
Thus, ancient African apemen travelled half the world, made homes across Indonesia and, in one case, were washed out to sea to end up colonising a remote island that was already populated with pygmy elephants, called stegadons, and giant Komodo dragons, which are still found on the island. It is a truly fantastic tale, worthy of Rider Haggard, and it has turned the study of human evolution on its head.
And then there is the report that dates the stone tools found on Flores as being 1.1 million years old. "That is utterly remarkable on its own," adds Morwood. "Until we found these dates, the longest period of island isolation that we knew about occurred on Tasmania where the aboriginal people were cut off from mainland Australia 11,000 years ago. We thought that was an amazing length of time. But now we have found an island where early humans were cut off from the rest of evolution for more than a million years." In addition, there are those completed digs carried out by Morwood which suggest that some type of human being was making stone implements up to two million years ago.
A crucial aspect to this remarkable story is the region's geography, Morwood believes. The ocean currents and the remoteness of Flores make the island difficult to get to, so once a species does get there, it will remain well protected on it, he argues. "Flores seems to protect species that are long past their use-by dates. There were those pygmy elephants, and the Komodo dragon, for example. And now we have Homo floresiensis. It may be that only a few animals get there but when they do arrive they tend to survive for a long time, which has been science's good fortune."
That is putting it mildly. Had not the original Australian team, led by Morwood, uncovered those hobbit remains in 2004, the story of humanity's African exodus would have been considered a fairly simple affair.
According to this version of events, Homo erectus evolved from apemen predecessors, such as Australopithecus africanus, in Africa and then headed off around the Old World more than a million years ago, armed with a great physique and a modest intellect. These allowed it to settle across Africa, Asia and Europe. This diaspora was then followed by a second wave of humans – our own species, Homo sapiens – which emerged from Africa 100,000 years ago and took over the planet, replacing all pockets of its predecessors it encountered.
Now a far more complex picture is emerging. Ancient apemen, who might have been thought to lack the nous for global conquest, appear to have done the trick almost a million years earlier. One of the major tenets of human evolution, the story of our world conquest, is now urgently in need of revision.
As to the fate of H. floresiensis, that is unclear. The species disappears abruptly from the archaeological record 17,000 years ago. But why? They had apparently survived quite happily on the island for more than a million years. So what did for them in the end?
There are two competing answers. The first suggests that the species, after all the good fortune that had helped it endure the vicissitudes of life in the Malay Archipelago, ran out of luck. "There is a thick layer of ash in the Liang Bua cave above the most recent hobbit remains," says Stringer. "We now know this was caused by a major volcanic eruption which occurred about 17,000 years ago. So it may be that they were just unlucky with the local geology." According to this vision, the little folk of Flores were wiped out by choking plumes of volcanic ash or died of starvation on an island denuded of vegetation.
It would have been a pretty terrible way to go. Yet neither Stringer nor Morwood is convinced that was what happened, despite the tight link between dates of eruptions on the island and the disappearance of the species from the fossil record. Instead, they suspect a very different agent: the bloody hand of modern humans. "Look at our track record," says Morwood. When Homo sapiens entered Europe 40,000 years ago, on its route out of Africa, they would have encountered the continent's original inhabitants, the Neanderthals. Within a few millenniums, the Neanderthals had been rendered extinct.
Stringer agrees. Homo sapiens left Africa about 100,000 years ago and by the time hobbits became extinct on Flores, modern humans were all over south-east Asia. "I cannot see Homo floresiensis keeping modern humans off the island. There must have been encounters between them and us. It is wonderful to speculate what might have happened when they met up, but I suspect that those moderns used up the resources that the hobbit needed to survive."
Robin McKie is the science editor of the Observer
http://www.guardian.co.uk/science/2010/feb/21/hobbit-rewriting-history-human-race
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bat400
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| Posted 07-04-2010 at 04:47
Submitted by coldrum ---
Neanderthal may not be the oldest Dutchman
People may well have been roaming the land we now call the Netherlands for far longer than was assumed until recently. There is evidence to suggest that the country was home to the forebears of the Neanderthals. Amateur archaeologist Pieter Stoel found materials used by the oldest inhabitants in the central town of Woerden. These artefacts were shown to be at least 370,000 years old, which takes us back to long before the time of the Neanderthals.
Our ancient forebears are often described as cavemen but that is not entirely accurate. Explains Pieter Stoel:
"They can best be described as people who travelled through the country along the rivers, where they could easily hunt the animals that came to the water to drink. At the time when they possibly roamed the Netherlands, the North Sea was dry, which would have enabled them to walk to England for example."
Pieter Stoel is an amateur archaeologist. For 14 years, he has conducted research in his spare time, alongside his day job as high school physics and chemistry teacher. But next year he intends to leave the classroom behind him and focus completely on his research. He describes the find in Woerden as unique.
"It consists of splinters and cores of flint. There are no hand axes, as they were not used by this culture. These items were sucked out of a sump pit at a depth of between 27 and 36 metres."
Research institute TNO has studied the layers of soil and determined the age of the objects raised during the dredging work. The remarkable conclusion is that they are at least 370,000 years old.
Follow-up research is needed to show whether the artefacts actually come from the layers at the bottom of the pit or whether they were shifted by the dredging work. A layer by layer study is now being carried out to see which artefacts are located where.
"We are still awaiting conclusive evidence."
A similar find has already been made in the British town of Pakefield. This makes sense given that Pakefield and Woerden are only 225 kilometres apart as the crow flies. During that period, the two countries were not separated by the sea. It could well be that the forebears of the Neanderthals walked from Woerden to Pakefield.
"It was a pleasant enough climate and all they had to do was follow the Meuse and the Rhine."
Pieter Stoel’s discovery may end up rewriting history. Until now, the assumption was that the ancestors of the Dutch walked from France to England and only arrived in the Netherlands at a later date. But the archaeologist now thinks the opposite might be just as plausible.
"There may even have been various migration flows. There may well have been people who made hand axes and who migrated from France to England. But it is also plausible that people whose culture did not include the hand axe arrived in England from Europe, via Germany and the Netherlands."
Fore more, see:
http://www.rnw.nl/english/article/neanderthal-may-not-be-oldest-dutchmanhttp://www.rnw.nl
[ This message was edited by: bat400 on 2010-04-07 04:48 ]
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coldrum
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| Posted 26-04-2010 at 18:02
Neanderthals may have interbred with humans
Genetic data points to ancient liaisons between species.
Archaic humans such as Neanderthals may be gone but they're not forgotten — at least not in the human genome. A genetic analysis of nearly 2,000 people from around the world indicates that such extinct species interbred with the ancestors of modern humans twice, leaving their genes within the DNA of people today.
The discovery, presented at the annual meeting of the American Association of Physical Anthropologists in Albuquerque, New Mexico, on 17 April, adds important new details to the evolutionary history of the human species. And it may help explain the fate of the Neanderthals, who vanished from the fossil record about 30,000 years ago. "It means Neanderthals didn't completely disappear," says Jeffrey Long, a genetic anthropologist at the University of New Mexico, whose group conducted the analysis. There is a little bit of Neanderthal leftover in almost all humans, he says.
The researchers arrived at that conclusion by studying genetic data from 1,983 individuals from 99 populations in Africa, Europe, Asia, Oceania and the Americas. Sarah Joyce, a doctoral student working with Long, analyzed 614 microsatellite positions, which are sections of the genome that can be used like fingerprints. She then created an evolutionary tree to explain the observed genetic variation in microsatellites. The best way to explain that variation was if there were two periods of interbreeding between humans and an archaic species, such as Homo neanderthalensis or H. heidelbergensis.
"This is not what we expected to find," says Long.
Using projected rates of genetic mutation and data from the fossil record, the researchers suggest that the interbreeding happened about 60,000 years ago in the eastern Mediterranean and, more recently, about 45,000 years ago in eastern Asia. Those two events happened after the first H. sapiens had migrated out of Africa, says Long. His group didn't find evidence of interbreeding in the genomes of the modern African people included in the study.
The researchers suggest that the population from the first interbreeding went on to migrate to Europe, Asia and North America. Then the second interbreeding with an archaic population in eastern Asia further altered the genetic makeup of people in Oceania.
The talk at the anthropology meeting caught the attention of many researchers, some of whom have been trying to explain puzzling variations in the human genome. "They are onto something," says Noah Rosenberg, an anthropological geneticist at the University of Michigan in Ann Arbor, who heard the talk.
A test of the New Mexico team's proposals may come soon. Svante Pääbo and colleagues at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, announced early last year that they had finished sequencing a first draft of the Neanderthal genome, and they are expected to publish their work in the near future. Pääbo's earlier studies on components of Neanderthal genomes largely ruled out interbreeding, but they were not based on more comprehensive analyses of the complete genome.
Linda Vigilant, an anthropologist at the Planck Institute, found Joyce's talk a convincing answer to "subtle deviations" noticed in genetic variation in the Pacific region.
"This information is really helpful," says Vigilant. "And it's cool."
The paleontological record also is producing fossils that complement such interbreeding theories. Pääbo's team and Russian colleagues recently reported the mitochondrial genome of an archaic human from the Altai Mountains — in southern Siberia near ancient Asian trade routes1.
The ancient mitochondrial DNA came from a piece of finger bone, which the groups haven't identified by species. It could be Neanderthal, a new Homo species or some other archaic form — like H. erectus, who spread to Oceania by 1.8 million years ago.
The Pääbo team reported that the bone was from an individual that lived 30,000–48,000 years ago in Denisova Cave, near where both modern humans and Neanderthals then dwelled. But the age of the bone has been questioned by researchers, who say the cave's sediments may have been reworked, making the bone's layer older.
At the anthropology meeting, Theodore Schurr, a molecular anthropologist at the University of Pennsylvania in Philadelphia, said the genetic model showing interbreeding raises questions about the range of species, like H. heidelbergensis. He noted that human skeletons found at Lake Mungo in New South Wales, Australia, have robust features, which may represent the result of interbreeding; they are dated to more than 20,000 years ago.
Keith Hunley, another member of the New Mexico group, said the team is now moving to publish its results in the near future.
http://www.nature.com/news/2010/100420/full/news.2010.194.html
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coldrum
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| Posted 26-04-2010 at 18:03
Early humans may have bred with other species – twice
Human evolution is looking more tangled than ever. A new genetic study of nearly two thousand people from around the world suggests that some of our ancestors bred with other species of humans, such as Neanderthals, at least twice.
"The researchers suggest the interbreeding happened about 60,000 years ago in the eastern Mediterranean and, more recently, about 45,000 years ago in eastern Asia," Nature News reports from the annual meeting of the American Society of Physical Anthropologists in Albuquerque, New Mexico.
That conclusion is based on a study of over 600 genetic markers, called microsatellites, sequenced in nearly 100 different populations.
As humans began fanning out from Africa, between 50 and 100,000 years ago, these markers changed, allowing researchers to determine the relationship between different populations and to estimate when they split from one another.
If humans bred only with other humans, all these markers would create a neat phylogenetic tree, showing that human genetic diversity can be traced to a single population that existed in Africa in the last 100,000 years.
Instead, a team led by Jeffrey Long, at the University of New Mexico, found evidence that some of the markers looked far too old to have come from humans. Inbreeding with other ancient species is the likeliest explanation. "It means Neanderthals didn't completely disappear," he told Nature.
True, Neanderthals are the likeliest contenders for our ancestors' sexual partners, but they aren't the only ones.
Last month, a team at the Max Planck Institute for Evolutionary Anthropology in Leipzig Germany recovered hominin DNA in Mongolia from a 30-50,000-year-old finger bone that appears to be neither Neanderthal nor human. Its ancestors, or another yet-to-be-discovered kind of archaic hominin, could have bred with humans.
Previous studies of small parts of the Neanderthal genome have found no evidence for interbreeding.
But with a complete Neanderthal genome due to be published any day now, and more DNA from the newly-discovered hominin in the works, scientists will have the best chance yet to determine whether our species shared a bed with any others.
http://www.newscientist.com/blogs/shortsharpscience/2010/04/early-humans-may-have-bred-wit.html?DCMP=OTC-rss&nsref=online-news
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coldrum
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| Posted 26-04-2010 at 18:21
“X-Woman” coexisted with Neanderthals and modern humans 40,000 years ago
A new study has suggested that an unknown type of human, nicknamed “X-Woman,” coexisted with Neanderthals and our own species between 30,000 to 50,000 years ago.
According to a report in Discovery News, the as-of-yet-unnamed new human species represents the first time that a hominid has been described not from the structure of its fossilized bones, but from the sequence of its DNA.
Researchers focused on mitochondrial DNA (mtDNA), genes passed down from mothers to their children – hence the X-Woman nickname.
Her mtDNA shows that X-Woman shared a common ancestor with Neanderthals and modern humans one million years ago, so X-Woman and her species likely migrated out of Africa 500,000 years before the ancestors of Neanderthals left Africa.
Modern humans are thought to have made the journey much more recently, at just 50,000 years ago.
“So whoever carried this mtDNA out of Africa was a creature that was not on our radar screen before,” co-author Svante Paabo told Discovery News.
Paabo, who is director of the Department of Genetics at the Max Planck Institute for Evolutionary Anthropology, and his colleagues made the discovery after extracting and sequencing mtDNA from a single pinky finger bone.
The bone, probably from a child, was found at Denisova Cave in the Altai Mountains of southern Siberia.
The genetic sequence was then compared with those for 54 present-day modern humans, a Late Pleistocene early modern human from Russia, six complete Neanderthal mtDNAs, one bonobo and one chimpanzee.
None of them matched with the new sequence, but they revealed that the individual was a human that carried twice as many genetic differences as Neanderthals do with our species.
Since Neanderthals and modern humans were also living less than around 62 miles away in Siberia at the time, Paabo said, “At least three different forms of humans may have coexisted 30,000 to 40,000 years ago,” making human history “a lot more complex and interesting” than previously thought for this period.
Based on archaeological finds from Denisova Cave, the researchers suspect X-Woman and her species, along with the Neanderthals and modern humans, hunted large game, such as woolly mammoths and woolly rhinos.
Conditions were often cold then in Siberia, as they are now, so everyone probably wore heavy, protective clothing.
Ornaments dating to the period, such as bracelets, were also found in the cave.
Because the different humans appear to have lived within close proximity of each other, this “increases the potential for interaction,” including inbreeding, according to Paabo. (ANI)
http://www.24worldnews.com/x-woman-coexisted-with-neanderthals-and-modern-humans-40000-years-ago/6193/
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coldrum
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| Posted 26-04-2010 at 18:22
Brain Parts Found in Ancient Human Ancestor
Electromagnetic radiation revealed parts of the 1.9-million-year-old brain, as well as eggs of insects that fed on it.
* A remnant of brain may be present in the remains of a new human ancestor.
* Fossilized insect eggs whose larvae may have fed on the ancestor could also be present.
* The 1.9-million-year-old hominid's species is thought to have given rise to modern humans.
Remains of a 1.9-million-year-old human ancestor are so well preserved that they may contain a remnant of the male individual's brain, according to the European Synchrotron Radiation Facility in Grenoble, France, where the remains were recently examined.
While DNA is very fragile and deteriorates over time, the discovery opens up the remote possibility that soft tissue with preserved DNA still exists in the prehistoric hominid, which could hold an important place on the human family tree.
The examination also turned up what seemed to be fossilized insect eggs, according to scientists. They said larvae from the eggs could have fed on the flesh of the human ancestor, Australopithecus sediba, right after his death.
While gazing at the hominid's skull as it was being studied with a powerful electromagnetic radiation X-ray process, project leader Lee Berger said he and his team were seeing "structures we can't even imagine in a way that's quite literally unprecedented in paleontological sciences."
Berger, a senior research officer and director of the School of Geosciences at the University of Witwatersrand, and his colleagues focused on the teeth and "parts of the body that don't normally fossilize," such as the brain. While further testing is needed, the researchers believe an "extended shadow" hints that a remnant of the brain after its bacterial decay is still present in the ancient remains.
self esteem
WATCH VIDEO: Clues from the pelvis of the human ancestor, Ardi, indicate she walked upright on two legs, not on all four like chimpanzees.
Related Links:
* New Ancestor May Be Ape-Human Link
* Slide Show: Faces of Our Ancestors
* Planet Green: Nine-Year-Old Accidentally Discovers a New Species of Human Ancestor
* 'Ardi,' Oldest Human Ancestor, Unveiled
* HowStuffWorks.com: Are we all descended from a common female ancestor?
"We actually think we have found the best candidate for a direct ancestor of Homo, the genus to which humans belong," Berger's colleague Darryl de Ruiter of Texas A&M University said. They and other researchers co-authored a paper on Australopithecus sediba that appears in the latest issue of Science.
So far, two fossilized skeletons for this species with both primitive and more human-like traits have been excavated. One set belonged to an adult female. The other belonged to a nine- to 13-year-old male, which underwent the X-ray synchrotron process that allows scientists to visualize minute details inside a fossil without having to break it open.
"When I first saw the skeletons, I knew we had something special," said de Ruiter. "Both were remarkably complete and extremely well preserved."
The fossilized skeletons were found deep in a South African cave, where the prehistoric individuals had likely sought water before plunging to their deaths and being buried by a roof collapse within the cave.
The researchers are not providing further details yet on the possibly detected brain segment and fossilized insect eggs, as they say the results are still "preliminary" and have not yet been published in a peer-reviewed journal.
Human brain tissues have been found dating to over 8,000 years ago, but there is little direct evidence for hominid brain structure before that time, aside from what is suggested by the shape of skulls.
"For a long time, paleontologists have used the shape of the cranial cavity to research the general morphology of the brain -- because soft tissue was not available until today," said Alan Pradel of Paris' National Museum of Natural History.
Pradel was one of the scientists who recently discovered a 300-million-year-old fossilized brain in a now-extinct relative of a modern "ghost shark" chimaera.
"Soft tissue has fossilized in the past, but it is usually muscle and organs like kidneys because of phosphate bacteria from the gut that permeates into tissue and preserves its features," added the American Museum of Natural History's John Maisey, who worked with Pradel in identifying the chimaera brain, which is now believed to be the world's oldest fossil brain.
Berger and his team are at present still analyzing the "terabytes of data" from the X-ray synchrotron examination of the hominid remains. In the future, they hope to use this process to not only reveal further information about A. sediba, but also other fossils that they have found in South Africa.
http://news.discovery.com/human/brain-human-ancestor-skull.html
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coldrum
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| Posted 26-04-2010 at 18:24
New Fossil Fits as 'Missing Link,' Scientists Argue
Is the newly-found Australopithecus sediba the missing link between humans and ape-like beings? Many are claiming it could be.
* Fossils for a new human ancestor suggest it's the transitional species that gave rise to humans.
* Remains previously attributed to the genus Homo may actually belong to australopithecines.
* A remnant of the new human ancestor's dried brain may exist, and could yield DNA.
A new human ancestor recently found in South Africa is poised to forever change the human family tree and what it means to be human, with some scientists arguing the 1.9-million-year-old species represents the so-called missing link between modern humans and ape-like beings.
At the same time, the news that the fossil contains remnants of brain matter poses the possibility of recovering DNA of an ancient ancestor, leading to unprecedented information about the early hominid and our own human lineage.
Scientists working on the project told Discovery News that they have discovered even more fossils at the same Malapa cave site. All of the hominid remains come from the new ancestor, Australopithecus sediba, which lived around 1.9 million years ago. Some scientists believe that it's the transitional species between more ape-like beings and our closer relatives in the genus Homo.
For more stories and interactives on the discovery of Australopithecus sediba and on human evolution, click here.
The discovery of "Sediba," which means wellspring, appears in the latest issue of the journal Science.
Co-author Steven Churchill and his colleagues now think it's likely that an even earlier, more ape-like human ancestor, Australopithecus africanus, gave rise to A. sediba, which they suspect evolved into Homo erectus.
"If you lay out all specimens of Australopithecus africanus on one side of a table and specimens for Homo erectus on the other side, Australopithecus sediba serves as a nice morphological intermediate between those two," Churchill, associate professor of evolutionary anthropology at Duke University, told Discovery News.
self esteem
WATCH VIDEO: Clues from the pelvis of the human ancestor, Ardi, indicate she walked upright on two legs, not on all four like chimpanzees.
Project leader Lee Berger of the University of Witwatersrand added, "Sediba shows a strange mix of primitive australopithecine traits and derived Homo traits."
He explained that parts of its face, its long orangutan-like arms, and its feet and ankles are more primitive features, but its pelvis, lower limbs, and back teeth are more human.
Dissenting Views
Not everyone, however, believes A. sediba gave rise to humans.
Richard Potts, director of the Smithsonian's Human Origins Program, has pointed out that there is evidence for the genus Homo that predates A. sediba, such as an upper jawbone previously attributed to Homo habilis that dates to 2.3 million years ago.
Anthropologist Fred Grine of Stony Brook University echoed Potts' concerns.
Berger and his team, however, think that many fossils currently identified as being in the genus Homo are actually australopithecines. Churchill suggested that all fossils for Homo habilis and Homo rudolfensis might actually fall within the genus Australopithecus.
"Australopithecus sediba raises the bar on what it takes to determine if something is in the genus Homo," explained Berger, who added that many claims for early humans were just based on fragmentary evidence, such as a handful of jawbones that were dated based on surrounding fauna.
"If we only had the mandible for sediba, we would probably be calling it something else entirely, maybe Homo habilis," he said. "We learn from sediba that you need more than just one part of the anatomy, more than fragments, and that context is everything."
Intact DNA?
One sediba individual, a male juvenile who died at about the age of 13 after plunging down a cave, is so well preserved that high-powered X-rays recently suggested part of his brain might still exist. An extended low-density area was detected in the individual's skull where the brain is located.
"It is our colleague Paul Tafforeau, a specialist in imaging at the European Synchrotron Radiation Facility in Grenoble, France, who feels it is organic in shape and may be the remnant of the 'dried' brain," Berger said. "We shall wait and see."
The X-ray process also showed what could be fossilized eggs whose larvae may have fed on the flesh of the young male shortly after death. If the brain yields soft tissue, or if these insects or other matter is well enough preserved, there is a slim chance they could yield DNA that might unlock the genetic code for A. sediba.
If this happened, unprecedented details about an early hominid would shed light on its history and overall make-up. It could also open the door to bringing such an individual back to life through cloning, but that possibility is extremely remote and controversial.
"We are looking to see if any proteins are preserved in any possible organics at Malapa," Berger concluded. "Again, time will tell."
http://news.discovery.com/human/missing-link-human-ancestor-sediba.html
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coldrum
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| Posted 26-04-2010 at 18:26
'Java Man' takes age to extremes
New dating of Indonesian strata produces unexpected results.
New age estimates for Homo erectus fossils on the Indonesian island of Java have physical anthropologists scratching their crania.
After convincing most of their colleagues that H. erectus may have persisted on the Indonesian island of Java as recently as 30,000 years ago — late enough to have coexisted in Asia with modern humans for more than 100,000 years — anthropologists presented new analyses April 14 suggesting the fossils in question may actually predate Homo sapiens by hundreds of thousands of years.
It all depends which radiometric method you use to assess the fossils’ age, New York University anthropologist Susan Antón reported at the annual meeting of the American Association of Physical Anthropologists.
Antón and an Indonesian colleague lead a team that first announced in 1996 that sediment at two H. erectus sites on Java dates to between 50,000 and 30,000 years ago. Those “remarkably young” dates, based on analyses of radioactive elements in fossil-bearing sediment, suggest that H. erectus survived well into the era dominated by modern humans, Antón said. Many researchers now accept those dates.
But a new analysis, based on measurements of radioactive argon’s decay in volcanic rock above and below the fossils, puts H. erectus’ age on Java at roughly 550,000 years. It’s not clear why these estimates differ so dramatically and which one is more accurate, Antón said.
“It’s confusing right now, but I suspect that Homo erectus’ age on Java is still relatively young,” said Christopher Stringer of London’s Natural History Museum. A new analysis of sediment on Java suggests that animal fossils on the island date to between 200,000 and 150,000 years ago, providing a possible framework for when H. erectus lived there, he added.
http://www.sciencenews.org/view/generic/id/58346/title/Java_Man_takes_age_to_extremes
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coldrum
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| Posted 26-04-2010 at 19:49
Ancient Hominids Had Human-Like Grip
Hominids may have evolved opposable thumbs long before they figured out how to make tools.
* Prehistoric hominids may have evolved opposable thumbs earlier than once thought.
* A tiny fossil suggests hominids had a human-like grip at least 6 million years ago.
* That's well before the earliest evidence of stone toolmaking, about 2.6 million years ago.
A tiny fossil thumb bone provides a gripping look at the early evolution of human hands, according to a study presented April 16 at the annual meeting of the American Association of Physical Anthropologists.
An upright gait and a relatively sophisticated ability to manipulate objects apparently evolved in tandem among the earliest hominids at least 6 million years ago, said Sergio Almécijaof the Autonomous University of Barcelona. That's well before the earliest evidence of stone toolmaking, about 2.6 million years ago, arguing against the idea that fine motor skills for toolmaking drove the evolution of opposable thumbs.
Almécija and his colleagues studied a bone from the tip of a thumb belonging to Orrorin tugenensis. At an estimated 6 million years old, Orrorin is the second oldest hominid genus. A more recently identified hominid genus and species, Sahelanthropus tchadensis, may have lived 7 million years ago. Controversy exists over whether fragmentary Sahelanthropus and Orrorin fossils can be used to identify new hominid genera.
Limb and jaw pieces, as well as teeth, from at least five Orrorin individuals were unearthed in Kenya in 2000.
The thumb fossil indicates that Orrorin had a long enough thumb to meet the tips of the other fingers, allowing for fine manipulation of objects.
"The Orrorin thumb bone is the most human-like in the available fossil record, other than recent Homo species," Almécija said.
By comparing Orrorin's thumb with thumb bones from a variety of ancient apes and hominids, as well as from living people, Almécija uncovered a pattern that he says argues against the current notion that hominids first evolved handier hands as they learned to make stone tools. No Sahelanthropus thumb bones have been found.
In Almécija's view, early hominids inherited hands capable of fine manipulation from small-bodied apes that lived in Africa and Europe between 25 million and 5 million years ago. Hands then assumed a more apelike, less dexterous structure in later hominids, including Ardipithecus and Australopithecus, before again evolving a precision grip in the Homo lineage.
Orrorin's human-like thumb calls into question a long-standing assumption that 1.8-million-year-old hand fossils from Homo habilis, unearthed in Africa more than 40 years ago, represent the earliest transition to a precision grip, he added.
Almécija's group compared the Orrorin thumb bone to corresponding fossils from later Australopithecus and Homo. species, as well as to ancient apes. Many extinct apes possessed short hands with long thumbs suitable for tightly grasping objects or tree limbs, Almécija said. That arrangement served as the foundation for the evolution of early hominid hands, he hypothesized.
Russell Tuttle of the University of Chicago had previously predicted that early hominids had a relatively sophisticated grip. Tuttle called the new analysis of Orrorin's thumb "unsurprising." But what Orrorin would use a precision grip for is unclear, Tuttle noted. A thorough comparison of the Orrorin fossil to thumb bones from various living primates is needed, in his view.
"A chimp could knock out a basic stone tool with its hands if it had the cognitive ability to try to do so," Tuttle said.
Tuttle originally analyzed the H. habilis hand fossils cited by Almécija. The new evidence doesn't alter the status of those finds as representative of a key transition in hand anatomy related to stone toolmaking, Tuttle argued.
Another meeting presentation, delivered just after Almécija's, suggested that Orrorin's human-like thumb didn't necessarily evolve to support toolmaking. Erin Marie Williams of George Washington University in Washington, D.C., described surprising evidence that even the thumbs of living people aren't specially designed to enable the high-impact strikes of one stone on another needed to produce sharpened implements.
"This calls into question hypotheses linking modern human thumb anatomy specifically to stone tool production," Williams said.
Williams and George Washington University biological anthropologist Brian Richmond attached special sensor devices to the fingers of six experienced stone toolmakers as they used a "hammer stone" with one hand to strike sharpened flakes from another stone.
Volunteers usually snapped their wrists as they hammered on stones, often delivering the most force and pressure to fingers other than the thumb, Richmond said. This argues against the thumb being especially important for this type of toolmaking.
http://news.discovery.com/archaeology/ancient-hominids-thumbs.html
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coldrum
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| Posted 26-04-2010 at 19:50
Hobbit debate goes out on some limbs
Arm and leg fossils may, or may not, come from nonhuman hominid.
Two fossil hobbits have given what’s left of their arms and legs to science. That wasn’t enough, though, to quell debate over hobbits’ evolutionary status at the annual meeting of the American Association of Physical Anthropologists on April 17.
Since 2004, the discoverers of unusual “hobbit” fossils on the Indonesian island of Flores have attributed their find to a pint-sized species, Homo floresiensis, that lived there from 95,000 to 17,000 years ago. These researchers also suspect, on the basis of hobbit anatomy and recent stone tool discoveries on Flores, that H. floresiensis evolved from a currently unknown hominid species that migrated from Africa to Indonesia more than 1 million years ago.
Critics say the finds represent nothing more than human pygmies like those still living on Flores. In their opinion, the centerpiece hobbit find — a partial skeleton of an adult female known as LB1 — is what’s left of a woman who suffered from a developmental disorder that resulted in an unusually small brain and a misshapen skull and lower body.
But arm and leg fossils from LB1 and a second hobbit appear robust, not unhealthy, according to a new study directed by William Jungers of Stony Brook University in New York. The bones display humanlike thickness in the tough tissue that forms the outer shell of most bones, and opposite sides of the limb bones exhibit comparable thickness, a sign of healthy growth, said Stony Brook anthropologist and study coauthor Frederick Grine, who presented Jungers’ paper at the meeting.
Hobbits also possessed much stronger limbs relative to body weight than either Homo sapiens or its presumed predecessor, Homo erectus, Jungers’ team concluded.
Limb strength for H. floresiensis approaches that previously estimated for more ancient hominid species such as the 3.2-million-year-old Australopithecus afarensis — a.k.a. Lucy — and 2.3-million-year-old Homo habilis, according to Junger’s analysis.
These results imply that hobbits were able to engage in vigorous physical activities that neither modern humans nor H. erectus could manage. Hobbits may have spent much of their time climbing trees, as Lucy’s kind did, the Stony Brook researchers propose.
Hobbits’ mix of humanlike and Lucy-like limb traits fits with Jungers’ recent proposal that a primitive, currently unknown hominid species trekked from Africa to Flores at least 1.8 million years ago and evolved into H. floresiensis. Earlier suggestions that hobbits descended from H. erectus (SN: 10/30/04, p. 275) have been dropped.
Junger’s group used computerized tomography images to calculate bone thickness at points along the length of six hobbit bones from the upper arm and the upper and lower leg. Five fossils came from LB1 and one came from another hobbit adult. The researchers then compared these data to corresponding measures for Lucy, H. habilis and several hundred people from different parts of the world, including Indonesian pygmies now living on the Andaman Islands.
Estimates of arm and leg strength for LB1 were generated by comparing her bone thickness to her height and weight — roughly 3 feet, 5 inches and 66 pounds, according to Jungers. But hobbit skeptics put LB1’s height at 4 feet or more, a stature that would imply weaker limbs than the Stony Brook researchers contend.
In another meeting presentation, Robert Eckhardt of Pennsylvania State University in University Park argued that a developmental disorder produced a suite of skeletal abnormalities in LB1 (SN: 11/18/06, p. 330), including irregularly shaped hip joints and tube-shaped upper leg bones. Junger’s new limb-bone analysis doesn’t address those points, Eckhardt said.
A variety of developmental disorders produce skeletal traits in people today that Jungers has labeled as exclusive to H. floresiensis, Eckhardt added.
At the meeting, he described the case of a woman with a developmental disorder that resulted in an S-shaped collar bone. Jungers’ team includes this characteristic in a list of hobbit-specific skeletal features.
This new twist in the hobbit controversy follows the March 17 online publication of a paper in Nature concluding that hominids reached Flores by 1 million years ago. Excavations on Flores yielded stone tools from sediment dating to that time, reported Adam Brumm of the University of Wollongong in Australia.
Brumm previously uncovered 800,000-year-old stone artifacts on Flores (SN: 6/3/06, p. 341). He now suspects hominids reached the island as early as 2 million years ago.
Brumm’s contention has been challenged by colleagues who believe natural processes may have moved the artifacts from younger to older sediment layers.
Earthquakes and flooding are two of many possible ways in which stone artifacts could have been moved on Flores, noted James Phillips of the University of Illinois at Chicago.
If Brumm is right, only further fossil finds can determine what type of hominids reached Flores by 1 million years ago, remarked Robin Dennell of the University of Sheffield in England. “Until we get that evidence, we’re stumbling in the dark,” he says.
http://www.sciencenews.org/view/generic/id/58410/title/Hobbit_debate_goes_out_on_some__limbs
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| Posted 26-04-2010 at 20:36
Probing Question: What can we learn from Neanderthal DNA?
Contrary to their image as knuckle-dragging brutes, the Neanderthals on television play tennis and attend cocktail parties — and sell *****. In reality, these mysterious fellow hominids died out about 30,000 years ago. Today, an international research team is extracting DNA from Neanderthals who were, literally, cavemen. (Their bones were found in Croatian caves.)
What can we learn from the DNA of extinct humans?
"It can tell us a story about human history," says Webb Miller, Penn State professor of biology and computer science. Miller has been a leader in several major genome sequencing projects, which decipher the genetic code of all the chromosomes of an individual. Comparing the DNA sequences of modern and ancient humans can show us similarities and differences in our basic biology, he notes. It can tell us which prehistoric populations died out completely, and which contributed genes to modern humans. It can even be used to reconstruct the appearance of ancient humans. In 2007, scientists working on a single gene found that some Neanderthals may have had light skin and red hair.
As Miller explains, tens of thousands of years ago modern humans may have co-existed with Neanderthals, who were not Homo sapiens like us, but a different species, Homo neanderthalensis. Despite their differences, some say it's likely that a few prehistoric one-night stands occurred during that time. The question is whether they left a lasting impression in the form of genes shared between Neanderthals and modern humans for things like speech, language, and brain development.
Genetic information can also tell us about the travel patterns of ancient humans, says Miller. "The genome sequence of a man who lived in Greenland 4,000 years ago was published recently, and that information is being used to trace the movement of human populations." His genome tells us that this individual was part of a wave of people who invaded Greenland from Northeastern Siberia, about 5,000 years ago, Miller says, when it was already populated with people who had arrived over 5,000 years earlier. The data also show that he resembled modern-day Asians, with brown eyes, and dark skin and hair. He may also have been going bald.
Getting DNA from ancient humans isn't typically an easy task, Miller says, but the scientists who sequenced the Greenland sample were lucky: they were able to take the DNA from a tuft of hair, which Miller and colleagues have shown to be a particularly good source material. The hair was found in permafrost, which also helped preserve the DNA.
The question almost everybody asks about genome mapping, says Miller, is "Can we bring them back? Can we clone these ancient prehumans or extinct animals?" That's definitely not the point of his research. Rather, he says, sequencing genomes from extinct and living individuals can illuminate the diversity in a species and its ancestors. For humans, this information can be valuable for understanding variations in disease susceptibility and response to treatment. For animals, sequence information is used to maintain diversity, for example in captive breeding programs for endangered species. Rather than bringing back humans or animals from extinction, Miller quips, "I'm just trying to keep the ones we've got."
He has communicated with the scientists on the Neanderthal genome project, and says they are preparing to publish their results. That means we might know soon if we have anything in common with the guys in the commercials, besides a need for cheap car insurance.
http://www.physorg.com/news191172239.html
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bat400
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| Posted 18-06-2010 at 05:07
Probing Question: What can we learn from Neanderthal DNA?
Submitted by coldrum ---
Contrary to their image as knuckle-dragging brutes, the Neanderthals on television play tennis and attend cocktail parties — and sell *****. In reality, these mysterious fellow hominids died out about 30,000 years ago. Today, an international research team is extracting DNA from Neanderthals who were, literally, cavemen. (Their bones were found in Croatian caves.)
What can we learn from the DNA of extinct humans?
"It can tell us a story about human history," says Webb Miller, Penn State professor of biology and computer science. Comparing the DNA sequences of modern and ancient humans can show us similarities and differences in our basic biology, he notes. It can tell us which prehistoric populations died out completely, and which contributed genes to modern humans. It can even be used to reconstruct the appearance of ancient humans. In 2007, scientists working on a single gene found that some Neanderthals may have had light skin and red hair.
As Miller explains, tens of thousands of years ago modern humans may have co-existed with Neanderthals, who were not Homo sapiens like us, but a different species, Homo neanderthalensis. Despite their differences, some say it's likely that a few prehistoric one-night stands occurred during that time. The question is whether they left a lasting impression in the form of genes shared between Neanderthals and modern humans for things like speech, language, and brain development.
Genetic information can also tell us about the travel patterns of ancient humans, says Miller. "The genome sequence of a man who lived in Greenland 4,000 years ago was published recently, and that information is being used to trace the movement of human populations." His genome tells us that this individual was part of a wave of people who invaded Greenland from Northeastern Siberia, about 5,000 years ago, Miller says, when it was already populated with people who had arrived over 5,000 years earlier. The data also show that he resembled modern-day Asians, with brown eyes, and dark skin and hair. He may also have been going bald.
From : http://www.physorg.com/news191172239.html
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| Posted 19-06-2010 at 11:19
Artefacts hint at earliest Neanderthals in Britain
Archaeologists have found what they say is the earliest evidence of Neanderthals living in Britain.
Two pieces of flint unearthed at motorway works in Dartford, Kent, have now been dated to 110,000 years ago.
The finds push back the presence of Neanderthals in Britain by 40,000 years or more, said Dr Francis Wenban-Smith, from Southampton University.
A majority of researchers believe Britain was uninhabited by humans at the time the flint tools were made.
An absence of archaeological evidence suggests people abandoned this land between 200,000 years ago (or 160,000 years ago, depending on who you ask) and 65,000 years ago.
But one researcher, unconnected with the study, said he was not convinced by the evidence presented so far.
Continue reading the main story
As soon as sea levels dropped, and a 'land bridge' appeared across the English Channel, they made the journey by foot to Kent
Dr Francis Wenban-Smith Southampton University
Dr Mark White, from Durham University, said he would like to assess the findings in detail before considering whether they posed a challenge to the majority view that humans were absent from Britain at this time.
A flint hand tool and a waste flake discarded by a Neanderthal whilst making a similar tool were unearthed at the M25 / A2 road junction at Dartford, during an excavation funded by the UK's Highways Agency.
Dr Wenban-Smith and colleagues from Oxford Archaeology have dated the sediments in which the hand axes were sitting to 110,000 years ago, placing them squarely within the "abandonment period".
The finds at Dartford come from when sea levels were dropping after a period when they were high enough to make the English Channel impassable.
Mammoth herds and Neanderthals (Oxford Archaeology) Neanderthals may have been drawn to Britain by mammoth and rhino herds
"We know that Neanderthals inhabited Northern France at this time, but this new evidence suggests that as soon as sea levels dropped, and a 'land bridge' appeared across the English Channel, they made the journey by foot to Kent," said Dr Wenban-Smith.
The dearth of evidence for human occupation in Britain between 200,000 and 65,000 years ago has perplexed researchers. The English Channel would have posed a physical barrier to humans trying to cross from the continent.
But sea levels fluctuated during this period; there were other times when hunters could have walked from France to southern England.
For instance, from 200,000-130,000 years ago the sea level was predominantly low. Humans should have been able to get here, but, for some reason, they did not show up.
Opportunity knocks
"It could be something subtle like the rapidity of changing climate, altering its state from warmer to colder conditions. That may have meant it was too hard for the Neanderthals to develop a sustainable adaptation," Dr Wenban-Smith told BBC News.
"Neanderthals were cold adapted and maybe it just took them that time to adapt to the cold environment of that period. So that, before 130,000, they hadn't really cracked it. But after 115,000, they had cracked it."
Around 130,000 years ago, sea levels rose and Neanderthals would have been blocked from entering Britain by the English Channel. But around 115,000 years ago, sea levels fell again.
To Dr Wenban-Smith and his team, the flint tools from Dartford suggest that, this time, humans were able to take advantage of the opportunity.
Trench in Dartford (southampton University) The artefacts were found during works off the M25 motorway at Dartford
One theory is that Neanderthals may have been attracted back to Kent by the flint-rich chalk downs visible from France. These supported herds of mammoth, rhino, horse and deer - an important source of food in sub-arctic conditions.
The finds were dated using a method known as optically stimulated luminescence (OSL). This exploits the presence of radioactive isotopes in the natural environment.
Naturally occurring minerals such as quartz and feldspars record the amount of radiation to which they have been exposed.
Some minerals store a proportion of the energy delivered by the radiation and then release it at a later date in the form of light.
The amount of light released by such minerals can be used to calculate the radiation dose a sample has received and thus give an estimate of the time that has elapsed since it was buried.
Dates discarded
But Dr White raised doubts over the reliability of OSL dating, saying the technique was more or less "in constant development" - especially at this time range.
He added that assumptions about background radiation and average water content could significantly affect results.
"I haven't seen the flints, but I've no doubt they are genuine. Currently, with what has leaked to the press, I have no idea of the context of these finds," he told BBC News.
"I suspect there is a possibility the OSL dating [technique] might not be giving us the true date. And that would be my only [reservation]."
"I have similar dates from a site near Dover in Kent, which have come out between 90,000 and 100,000 years ago. But I don't think OSL is giving us a correct date and I have disregarded them."
Neanderthals split from our evolutionary line some 500,000 years ago. They were characterised by a short, muscular physique, a barrel chest, large brain and prominent facial features.
Dr Wenban-Smith along with other researchers think that "classic" Neanderthal features appeared about 200,000 years ago.
But other scientists describe much older fossils as Neanderthals. These include the 400,000-year-old partial skull unearthed at Swanscombe in Kent and 230,000-year-old human teeth excavated at Pontnewydd in Wales.
http://news.bbc.co.uk/1/hi/science_and_environment/10206677.stm
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coldrum
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| Posted 19-06-2010 at 11:24
Ancient ‘brain food’ helped humans get smart
Fossils bear evidence of the consumption of brain-building fish by hominids.
Between 1.9 and 2 million years ago, the brain size of our human ancestors increased dramatically. Now a trove of 1.95-million-year-old bone fragments from various animals adds evidence to a theory that these pre-humans owed this brainpower boost to fish.
The fossils, found in northern Kenya, bear cut marks from early stone tools and are the oldest evidence of the consumption of aquatic animals by human ancestors, said study researcher Brian Richmond, an anthropologist at George Washington University in Washington, D.C. The fatty acids found in the fish could have provided the nutrients the hominins needed to evolve larger brains, he said.
(Hominids include humans, chimpanzees, gorillas and their extinct ancestors, and hominins refer to species after the human lineage split from that of chimpanzees.)
While scientists have proposed a fishy diet as the reason behind the early brain boost, this concrete evidence for our ancestors' diet firms up the speculation.
The study, published this week in the journal Proceedings of the National Academy of Sciences, also revealed a huge variety in the hominin's diet. The butchered animal bones at the site suggest that antelope, rhinoceros, hippopotamus, catfish and even crocodiles were fair game for late Pliocene diners.
"It's wonderful that you can just come to this one source and see what was being eaten at this site 1.95 million years ago," said Peter Ungar, an anthropologist at the University of Arkansas who was not involved in the study. "They were consuming a much broader range of animals than our nearest living relatives do today."
Butchered bones
At the time the bones were butchered, the fossil site was wet and forested and was probably near a large river or lake. The research team's excavations revealed 506 fossil bone fragments that could be analyzed for the telltale marks of stone tools.
Six percent of the fragments had cut marks, which is a significant number given that butchering doesn't leave a mark on every bone, Richmond said. Only 1.9 percent of the bones had tooth marks from carnivorous animals, suggesting that the hominins either hunted the meat themselves or scavenged it quickly before other carnivores got to it.
The finding that ancient human ancestors ate fatty-acid rich aquatic animals is exciting, Richmond said, because it could help explain why brain sizes began to increase 2 million years ago.
"A diet that includes animal tissue, especially ones rich in brain-growth nutrients like fish, crocodiles and turtles, lifts the constraints on brain growth," Richmond told LiveScience. "This is the earliest evidence of a substantial contribution of these kinds of foods into the diet of our early human ancestors, and it occurs before we have evidence of a larger brain."
One piece of the puzzle
Still, aquatic animals are just a "piece of the puzzle" of early hominin diet, Ungar said. Eating fish certainly "didn't hurt" in the evolution of large brains, he said, but it may have been the diversity of diet that fueled hominin evolution rather than the individual components.
"It's not necessary to consume those aquatic resources, but it does provide for that dietary breadth," Ungar said.
The researchers can't tell for sure whether early hominins were hunting or scavenging, though the lack of tooth marks from other carnivores does provide for the "uncertain, but very exciting" possibility that our ancestors were hunters, said Osbjorn Pearson, an anthropologist at the University of New Mexico who was not involved in the study.
Either way, Richmond said, our hominin ancestors "were really good at finding meat and acquiring it. They weren't just being the vultures of the Pliocene."
http://www.msnbc.msn.com/id/37509593/ns/technology_and_science-science/
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coldrum
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| Posted 19-06-2010 at 11:25
Boffins find mystery seafaring ancestor in the Philippines
Anthropologists have discovered a foot bone during an excavation of Callao cave in Luzon, which has led to researchers’ claim that humans reached the islands off south-east Asia at least tens of thousands of years earlier than previously thought.
Armand Mijares of the University of the Philippines Diliman, and his colleagues insist the bone is definitely human, and they are provisionally calling it a lightly built modern human.
Mijares pointed out that its shape was unusual, and its size fell within the ranges of Homo habilis and Homo floresiensis.
It suggests that humans arrived on Luzon, the largest and northernmost major island in the Philippines, at least 67,000 years ago.
“The arrival of people in Australia 50,000 to 60,000 years ago is a good comparison,” New Scientist quoted expedition member Florent Detroit of the National Museum for Natural History in Paris, France, as saying.
“It seems coherent for us to think that in; south-east Asia and Australia, humans had sea-faring capabilities by 60,000 to 70,000 years ago.” (ANI)
http://www.thaindian.com/newsportal/health/boffins-find-mystery-seafaring-ancestor-in-the-philippines_100375049.html
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coldrum
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| Posted 19-06-2010 at 11:26
Did Neandertals Think Like Us?
João Zilhão defends his controversial view that our oft-maligned relatives shared our cognitive abilities.
* Scientists have traditionally considered Homo sapiens the only species to invent and use symbols.
* But over the past few decades archaeologists have discovered a handful of enigmatic artifacts hinting that our cousins the Neandertals—long dismissed as intellectually inferior—might have engaged in symbolic activities, too. Experts dismissed the finds, however, attributing them to modern humans instead.
* The recent discovery of Neandertal jewelry and body paint from two sites in Spain provides unequivocal evidence of Neandertal symbolism and suggests that modern human behavior has ancient roots.
For the past two decades archaeologist João Zilhão of the University of Bristol in England has been studying our closest cousins, the Neandertals, who occupied Eurasia for more than 200,000 years before mysteriously disappearing some 28,000 years ago. Experts in this field have long debated just how similar Neandertal cognition was to our own. Occupying center stage in this controversy are a handful of Neandertal sites that contain cultural remains indicative of symbol use—including jewelry—a defining element of modern human behavior. Zilhão and others argue that Neandertals invented these symbolic traditions on their own, before anatomically modern humans arrived in Europe around 40,000 years ago. Critics, however, believe the items originated with moderns.
But this past January, in a paper published in the Proceedings of the National Academy of Sciences USA, Zilhão and his colleagues reported on finds that could settle the dispute: pigment-stained seashells from two sites in Spain dated to nearly 50,000 years ago—10,000 years before anatomically modern humans made their way to Europe.
http://www.scientificamerican.com/article.cfm?id=did-neandertals-think-like-us
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coldrum
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| Posted 19-06-2010 at 11:27
Neanderthals feasted on lions
Looks like our ancestors could boast of the proverbial nerves of steel - Neanderthal cavemen hunted and feasted on lions, according to a new Spanish research.he study appears in the Journal of Archaeological Science.
Buzz up!
A team led by Ruth Blasco of the Universitat Rovira i Virgili in Tarragona, Spain, found lion bones at the Gran Dolina site in Sierra de Atapuerca.
The cave contains hundreds of animal bones, largely red deer and horses, but also a few carnivores in rock layers dating to 250,000 to 350,000 years ago.
One set of lion bones stands out among the other carnivores like foxes and bears.
"The relatively high occurrence of cutmarks on lion bones (11.76 percent) indicates an association between hominids (humans) and this predator," says the study, adding, "cutmarks related to the skinning and defleshing are identified and the human use of bone marrow is documented by diagnostic elements of anthropogenic (man-made) breakage. All these evidences suggest that the lion was used for food," reports USA Today.
The study also suggests cave diners hunted the lion, Panthera leo fossilis, a cave lion about seven feet long, considerably bigger than today's African lions.
"The fact that no pathologies have been documented on the P. leo fossilis remains, which indicate possible diseases or injuries of a traumatic nature that make this predator vulnerable," suggests that they hunted the big cat.
Even though early humans didn't hunt lions often, they likely resided higher than the cats on the food chain, the team says, concluding, "the hunting of this predator suggests that the hominids of the Middle Pleistocene are successful hunters able to face the large predators."
http://news.oneindia.in/2010/06/08/neanderthalsfeasted-onlions.html
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coldrum
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| Posted 19-06-2010 at 11:28
Humanity evolved to cope with 30°C+ heat, says prof
Scorchio conditions made us hairless, upright, sweaty.
Many of humanity's distinctive features - walking upright, hairlessness, the ability to sweat copiously - arose due to the fact that the place where we evolved has been scorchingly hot for millions of years, according to noted boffins.
The cradle of humanity, according to most research, was the Turkana Basin in Kenya's Great Rift Valley. Today this is a terrifically hot and arid place, but some scientists have argued that during the Pliocene and Pleistocene eras, when humanity was making its first appearance in the area, it must have been cooler and/or more wooded.
But now a crew of researchers headed up by Benjamin Passey of Johns Hopkins University say this isn't so - the Turkana area has always been cruelly hot, generally above 30°C and sometimes above 35°C, for the whole time humanity has existed.
“The ‘take home’ message of our study,” says Passey, “is that this region, which is one of the key places where fossils have been found documenting human evolution, has been a really hot place for a really long time, even during the period between three million years ago and now when the ice ages began and the global climate became cooler.”
The prof and his colleagues have determined this by examining rare isotopes of carbon and oxygen bonded together in soil carbonates. According to their calculations, at the time when humanity was appearing the daytime air temperature was generally 30°C or even higher.
“Thus, we can say that the ‘thermal hypothesis’ is credible," argues Passey.
The thermal hypothesis says that humans began walking upright, became unusually sweaty (for the animal kingdom) and shed their body hair in order to stay cool, rather than for other reasons such as shifting habitats among local wildlife. According to this theory, supported by the new isotope data, humanity is actually designed to live in a scorchingly hot climate. The human race's subsequent expansion across the globe has required innovations such as clothing, use of external energy sources (fire) etc.
http://www.theregister.co.uk/2010/06/09/turkana_heat_history/
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| Posted 19-06-2010 at 11:48
Neanderthal Route Through Kent - M25 find
Climate change may have brought Neanderthals from France – across a dry English Channel to Kent – 40,000 years earlier than previously thought. Theory has it they were attracted by the sight of the “white cliffs” rich in flint, or the migration of mammoth, rhino, horses and deer: precious foods in then sub-arctic conditions.
The whole story is told by a single flint hand tool and a waste flake discovered at the M25/A2 road works in Dartford in 2007. These have been dated by archaeologist Dr Francis Wenban-Smith of Southampton University and his team at Oxford Archaeology, by measuring the amount of radiation absorbed by the samples before they were buried (reports Tuesday’s Independent).
Chris Baker, Manager of Dartford Borough Museum said: “The road works in question have thrown up a number of discoveries all the way from Palaeolithic times, through the stone age, to the Romans, and up to World War II. This one is very exciting. If the flints are indeed 110,000 years old, that places them squarely in the ‘abandonment period when it was believed humans had not yet returned to Britain from the continent.”
“I do hope it may be possible to house the flints here in Dartford. It may be that they go to a national museum for further research, while we hold replicas. This has been the case with the 400,000 year old Swanscombe skull fragments, for example, whose originals are now housed at the Natural History Museum in London. Either way it looks likely to change our understanding and our exhibits about prehistoric England.”
But Dr Mark White of Durham University, who is not connected with the study, cautioned that the dating technique used is still under development. He said he would like to assess the findings in detail before considering whether they posed a challenge to the majority view that humans were absent from Britain at this time.
Named after the valley in Germany where their remains were discovered, Neanderthals were characterised by a short, muscular physique, a barrel chest, large brain and prominent facial features. They would have moved in “hunter gatherer bands” of up to 25 individuals, they made use of fire and relied on spears as their main hunting weapon. It is not known whether they wore clothes or relied on their own body hair for warmth.
Neanderthals split from the Homo Sapiens evolutionary line some 500,000 years ago and disappeared. However, scientists led by Svante Pääbo at the Max Planck Institute for Evolutionary Anthropology in Leipzig last month reported that between 1 and 4% of the DNA in today’s Europeans (and people in the Pacific) comes from Neanderthals. This means that after Homo Sapiens came out of Africa, and before it migrated to Asia, there was some interbreeding between the two types of early humans.
http://www.yourcounty.co.uk/localnews/neanderthalroute100610n1.html?
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