July 09, 2007
"The Glacial Period Did Not Happen Until Several Thousand Years After The Toba Super Eruption"
5 Jul, 2007 08:00 pm
Source: The Scitizen Initiative
Michael Petraglia is a University Lecturer in Human Evolution. His study published today in Science reveals that super-volcanic eruptions are perhaps not the cause of glacial periods as some had previously suspected.
Listen to the interview:
Click to se the team that worked in India
Modern Humans Lived in India Earlier Than Thought, Study Finds
By Chris Dolmetsch
July 5 (Bloomberg) -- Remains of stone tools found amid ash deposits in India from a volcanic eruption 74,000 years ago show that modern humans were living there earlier than scientists had previously thought, according to a study to be published in tomorrow's edition of the journal Science.
The Youngest Toba Tuff eruption in Indonesia, the largest volcanic event of the past 2 million years, blanketed an area from the South China Sea to the Arabian Sea with ash. Scientists had theorized that the blast produced a ``volcanic winter'' that lowered global temperatures, killing plants and animals and keeping humans from leaving Africa more than 60,000 years ago.
Study author Michael Petraglia, a University of Cambridge lecturer, and colleagues found tool fragments from soil both above and below a deposit of Toba Tuff ash, showing that humans were already in India at the time and survived the blast.
``This is some of the earliest evidence for the spread of modern humans out of Africa towards Australia,'' Petraglia said in a telephone interview from New York.
Petraglia and colleagues including Ravi Korisettar of Karnatak University in Dharwad, India, found 215 artifacts under a 2.55-meter (8.4-foot) thick ash deposit near Jwalapuram, in the Jurreru River valley of southern India, and 276 more relics above the layer.
Limestone, Quartzite Fragments
The study says the relics, made of limestone, quartzite, chert and other minerals, are likely from a variety of stone tools from the Indian Middle Paleolithic era that lasted from about 150,000 to 38,000 B.C.
Yet the characteristics of the artifacts are more typical of the African Middle Stone Age that ended about 40,000 years ago than they are of younger artifacts found elsewhere in Europe and Asia, the study says. That finding suggests that modern humans had migrated out of Africa and were already in southern India when the Toba Tuff eruption blanketed the region in ash.
``It will be very much debated,'' Petraglia said. ``There are people that are wedded to their theories and won't like it at all, and there are others who will welcome our study because this part of the world is very understudied.''
The research was funded by the Swindon, U.K.-based Natural Environment Research Council and its Arts and Humanities Research Council Oxford Radiocarbon Accelerator Dating Service, the Berkeley, California-based Leakey Foundation, the McDonald Institute for Archaeological Research, the Australian Research Council and Queens College in Cambridge.
To contact the reporter on this story: Chris Dolmetsch in New York at firstname.lastname@example.org .
Last Updated: July 5, 2007 14:00 EDT
Modern humans reached India early
SOurce: The Hindu
N. Gopal Raj
Evidence found in excavations by international team of scientists at Jwalapuram in Kurnool district of Andhra Pradesh
— Photo: Ravi Korisettar
Ravi Korisettar and Michael Petraglia (in the foreground) at one of the excavation sites.
THIRUVANANTHAPURAM: In the course of archaeological excavations at Jwalapuram in Kurnool district of Andhra Pradesh, an international team of scientists has found evidence that anatomically modern humans are likely to have reached India before a massive volcanic eruption in what is today Indonesia occurred tens of thousands of years ago.
The “super-eruption” of the Toba volcano in Sumatra some 74,000 years ago was the largest volcanic event to have occurred in the last two million years and the ash thrown up high into the atmosphere by that cataclysmic explosion reached India too, said Ravi Korisettar of the Department of History and Archaeology at Karnatak University in Dharwad, Karnataka.
During five years of excavations at Jwalapuram, Indian, British, and Australians scientists unearthed fine stone flakes that had been turned into tools for various purposes.
The stone tools were to be found in layers of earth above as well as below the fine ash from the Toba super-eruption, the scientists noted in a paper published in the latest issue of the journal Science.
It had been thought that the vast amounts of volcanic ash flung into the atmosphere by the eruption could have blocked sunlight and produced a “volcanic winter” that decimated the humans living then. But the evidence from the Jwalapuram excavations, however, suggests that the volcanic eruption did not have such a catastrophic impact on the early human population there.
The stone tools also pointed to a more exciting possibility. The stone tool assemblages found in Jwalapuram were “very similar to ones that we see produced in Africa at the same time,” said Michael Petraglia of the Leverhulme Centre for Human Evolutionary Studies at the University of Cambridge in the U.K, the first author of the paper.
Those stone tools in Africa had been produced by modern humans.
In the Science paper, the researchers noted that the techniques used for making the stone tools at Jwalapuram suggested “closer affinities” to African Middle Stone Ages traditions than to contemporaneous Eurasian ones. T his finding is significant because genetic studies of tell-tale patterns in the DNA of people living in various parts of the world have supported the view that all modern humans arose in Africa.
It is believed that these modern humans then migrated out of Africa and settled all across the globe.
“So what we are saying is that modern humans probably dispersed from Africa into India at a very early date, earlier than anyone has suggested before,” Dr. Petraglia told this correspomndent.
There is a hypothesis that modern humans could have taken the “southern route of dispersal,” utilising the coastlines to travel from Africa, through Arabia, across the Indian subcontinent and then into South-East Asia and finally into Australia, he said. The presence of modern humans in India at the time of the Toba super-eruption would be consistent with humans having used the southern route, but would remain speculative till further excavations were carried out in the Indian subcontinent and Arabian peninsula, remarked the scientists in their journal paper.
India has a played a key role in the migration of modern humans out of Africa, says K. Thangaraj of the Centre for Cellular and Molecular Biology at Hyderabad. In a paper published in Science two years ago, Dr. Thangaraj and others held that genetic lineages to be found among Andaman islanders supported an out-of-Africa migration by modern humans some 50,0000 to 70,000 years ago.
Dr. Korisettar is, however, sceptical about modern humans opting for a coastal route for their migration.
There was currently no archaeological evidence of such ancient human migrations along India’s west coast and into southern Tamil Nadu. Rather, the available archaeological data favoured a continental route whereby early humans came through the Bolan and Khyber passes to the north-western parts of the Indian subcontinent and then into Rajasthan before dispersing to other parts of the country, he added.
06.07.2007 / 20:27 Ancient humans in Asia survived super-eruption, find suggests
NEW YORK. July 6. KAZINFORM. A group of rocks that could easily be mistaken for gravel suggests that modern humans were in India spearing dinner and filleting meat 76,000 years ago, according to an international team of scientists.
The stone tools were found both above and below a layer of ash left behind by a volcanic "supereruption" 74,000 years ago. The discovery hints that humans in the region survived the blast's devastating effects.
The eruption of Toba, in what is now Indonesia, was the largest volcanic event of the last two million years.
Toba spewed as much as 720 cubic miles (3,000 cubic kilometers) of magma, rained sulfuric acid down as far away as Greenland, and sent the world into a volcanic winter followed by a severe ice age.
It showered all of India with nearly 6 inches (15 centimeters) of volcanic ash, which acts as a marker of age in Earth's strata today.
Anthropologist Michael Petraglia and his colleagues unearthed stone tool assemblages from above and below the Toba ash deposit in India's Jwalapuram Valley.
"We saw some stone tools above the ash, but we decided to test below the ash," said Petraglia, of the University of Cambridge, England, and primary author of the study.
"It was a lucky strike."
The tools the team found resemble those made by modern humans in Africa, suggesting that the Indian ones could have been made by humans, too, Petraglia said.
"The fact that we have this ash is just icing on the cake, because it tells us that if it's modern humans, then they were able to persist through a major eruptive event," he said. "But they would have had a very, very difficult time."
The study appears in the latest issue of the journal Science.
Volcanic Winter 74,000 years ago
The Toba eruption suspended volcanic gas and sulfuric acid in the stratosphere for years, reflecting warm sunlight away from Earth.
Ice cores reveal that the world was cooler by 5.4 to 9 degrees Fahrenheit (3 to 5 degrees Celsius) for several centuries following the event.
"It would have been more challenging times," said Will Harcourt-Smith, a paleontologist at the American Museum of Natural History in New York who was not involved in the study.
"My point is that humans were complex enough at this point to have dealt with that."
In Africa at this time, humans were exhibiting early symbolism, complex toolmaking behavior, and sophisticated social behavior, he said, Kazinform quotes National Geographic News.
"These people are not behaviorally like you or I, but they are modern humans and they have many of the vestiges of humanity," Harcourt-Smith said.
Humans or Neandertals?
Some experts caution that telling the difference between human-made stone tools and those made by the now extinct Neandertals (or Neanderthals) is tricky business.
"Previous research on this subject has shown that South African and Neanderthal European [stone tool] assemblages are technologically and typologically indistinguishable," said Stanley Ambrose, an archaeologist at the University of Illinois at Urbana-Champaign in Urbana who was not involved in the current study.
"[The study authors] have a bagful of artifacts on which they're drawing conclusions that can only be confirmed by fossil evidence, and they don't have any fossils."
Chris Clarkson, an archaeologist at Australia's University of Queensland and one of the study's authors, said a large piece of ground ochre was found below the ash with the stone tools. Ochre was used by early humans for art, symbols, curing hides, or helping to attach stone tools to build a wooden shaft.
"All of these potential uses hint at more complex behaviors than are usually attributed to earlier extinct hominin species, although we know European Neanderthals also used ochre a lot," Clarkson said.
"More excavation will help us resolve whether this assemblage belongs to modern humans or not."
Posted by Naxal Watch at 4:52 PM