|Aching Feet 5,200 Years Ago? |
By NAOMI KOPPEL
Associated Press Writer
ZUG, Switzerland January 12, 2001 (AP) — A piece of flattened moss discovered under a main road on the shores of a Swiss lake had archaeologists puzzled — until they discovered it contained the imprint of a foot. Now they have declared the item to be the oldest insole ever discovered, dating back some 5,200 years.
"At first we thought it was the remains of a piece of cloth, but we took it back to the laboratory and eventually we realized what it was,'' Stefan Hochuli, Zug state archaeologist, told The Associated Press.
The investigators found that one side of the moss had the imprint of a foot, while the other was flat, suggesting it had been pressed against a flat surface. They believe the insole would have fitted inside a leather shoe, but the shoe itself was destroyed by the wet lakeside soil. The insole is 10 inches long and was made for a shoe that today would be a men's size 6, Hochuli said. He added that he was amazed that a thin piece of moss had survived intact for so long and even more amazed that it had been discovered.
The archaeologists carried out their dig during the renovation of a main road through Zug, a town in central Switzerland. They already knew that it was the site of a lakeside Neolithic settlement, and the age has been confirmed through dating other items found at the location.
Hochuli said fewer than 10 shoes from that period have been discovered but that no one had ever found an insole as old as this. The most famous shoes are the ones worn by Oetzi, a body found perfectly preserved in the ice in the Alps between Austria and Italy in 1991. Others were found in the Netherlands, Spain, and at two sites in Switzerland.
Archeologists are completing work to preserve the insole, and then it will go on display at Zug's museum of prehistory, said Hochuli.
|By PAUL RECER |
SAN DIEGO January 9, 2001 (AP) - A supercluster of galaxies and quasars massed together across 600 million light years of space is the largest structure in the observable universe, astronomers say.
In a study presented Monday at the national meeting of the American Astronomical Society, researchers reported that the structure, which includes billions upon billions of stars, is believed to be 6.5 billion light years away.
"We have found nothing bigger in the (astronomy) literature and nobody has brought to our attention anything bigger," said Gerard Williger, a researcher at the National Optical Astronomy Observatories now working at NASA's Goddard Space Flight Center in Greenbelt, Md.
When viewed from Earth, the structure is just below the center of the constellation Leo the Lion. It stretches across an expanse of the sky of two degrees by five degrees, or an area about forty times that of the full moon as seen from Earth.
Williger said it is not known if the gathering of quasars and galaxies is bound together gravitationally or if it is a chance cluster formed by a ripple in the smooth expansion of the universe that followed the Big Bang, which is thought to have set off the formation of the universe.
"This may be an artifact of the Big Bang," he said, speculating that conditions at that point in space may have been uniquely ripe for the quick formation of stars, galaxies and quasars.
That such a large structure could form so quickly after the Big Bang calls into question some of the traditional theories of how the universe evolved, Williger said, since it is difficult to explain how gravity could pull together such an immense cluster in a relatively short time. Further study, which would include calculations of the mass in the structure, may yield new understanding.
"A successful theory has to explain the extremes," Williger said.
Light from the galaxies began its long journey about 6.5 billion years ago when the universe was just a third of its present age and the solar system, including the Earth, had not yet been formed, he said.
The structure includes at least 11 galaxies and 18 quasars in an area where the expected density of objects would be expected to include only two or three quasars and perhaps four galaxies, he said.
Quasars are galaxies with very active and bright center objects, thought to be powered by black holes. Quasars can shine with the brilliance of a trillion suns and astronomers can use this light to silhouette objects nearer Earth. Average galaxies, such as the sun's home, the Milky Way, can contain 100 billion stars. A light year is the distance light travels in a year in space, about 6 trillion miles.
Williger and his colleagues, using the four-meter telescope at the Cerro Tololo Inter-American Observatory in Chile, detected the supercluster's non-quasar galaxies indirectly, by analyzing the light received from quasars that are even farther away. This light is absorbed by the halos of gas surrounding the galaxies, producing shadows that reveal the presence of the galaxies.
There are other clusters of quasars in distant space, but none are as densely grouped as the supercluster in Leo, Williger said.
He said the Leo supercluster is more than twice the size of The Great Wall, a gathering of galaxies much closer to the Earth. The Great Wall is about 250 million light years across.
|Earth’s Senior Solid Hints At Early Start For Land and Life |
January 10, 2001 (AP) — Scientists have found a crystal believed to be at least 4.3 billion years old, making it the oldest known solid on Earth. And they say its sparkling facets contain hints that oceans, continents and perhaps even life itself developed much earlier than previously thought.
THE GRAIN of zircon, hardly wider than a human hair, was born in a molten fury not long after Earth formed. It was discovered inside younger stone in what is now Australia.
“It represents a significant advance in reconstructing Earth’s Dark Ages,” said geologist Alex Halliday of the Swiss Federal Institute of Technology in Zurich. He was not involved in the research.
Zircon is a durable crystal made of silicon, oxygen and zirconium, among other elements. The oldest grain identified is one of a dozen very old crystals extracted from the Jack Hills section of northwestern Australia.
TWO INDEPENDENT STUDIES
Two studies of the grains were conducted independently by international research teams. Their results were published in Thursday’s issue of the journal Nature.
One study reports that the oldest zircon is at least 4.3 billion years old. The second study puts its age at up to 4.4 billion years old.
“We are pretty confident,” said T. Mark Harrison, a UCLA geochemist and co-author of one of the studies. “Two studies conducted independently apparently have come to the same conclusion.”
Both research teams dated the zircon grains by analyzing their isotopes of uranium. Uranium decays into lead. By calculating the ratio of uranium to lead, they determined that a dozen of the grains were very old indeed.
Both teams used a high-resolution ion microprobe and a mass spectrometer to analyze the crystals.
EARTH’S EARLIEST CONDITIONS
Earth is believed to have formed into a terrestrial planet 4.56 billion years ago when swirling space debris and gas clumped together. The researchers said the zircon crystals grew from molten granite that formed at high temperatures more than 10 miles below the Earth’s surface.
The oldest crystal’s geochemical properties offer a glimpse into Earth’s early conditions.
Researchers said the zircon’s high level of heavy oxygen isotopes suggest it was cooled by surface water after it formed. If correct, this means that oceans appeared 200 million to 300 million years after Earth’s formation.
In this water, they speculate, simple life might have spawned. Current research holds that life appeared on Earth 3.9 billion years ago.
“Our results raise the possibility that a biosphere could have arisen on Earth 400 million years earlier than is now thought,” Harrison said. “But it’s not a smoking gun.”
The oldest known intact rocks on Earth, located in northwestern Canada, are 3.96 billion years old.
“The stage was set 4.3 billion years ago for life to emerge on Earth,” said University of Colorado astrobiologist Steven J. Mojzsis, Harrison’s colleague on the study. “There was probably already in place an atmosphere, an ocean, and a stable crust within about 200 million years of the Earth’s formation.”
|Australian study argues against ‘single migration’ theory |
By Guy Gugliotta
THE WASHINGTON POST
January 9, 2001 — Australian scientists studying ancient human fossils have recovered DNA that throws into question the theory that modern Homo sapiens spread throughout the world in a single migration out of Africa about 100,000 years ago.
INSTEAD, THE RESEARCHERS lend support to the “multiregional” hypothesis — that human ancestors left Africa about 1.5 million years ago, fanned out across the “Old World,” and evolved into modern humans.
The findings should provide fresh fuel for the spirited controversy among scholars over the origin of the modern, genetically similar humans who populate the world today and the fate of the ancestors who preceded them.
In a report scheduled for publication this month in the Proceedings of the National Academy of Sciences, the Australian team reported recovering a form of genetic material known as mitochondrial DNA from 10 fossils of Australians between 2,000 and more than 60,000 years old.
Nine of the 10 had DNA similar to contemporary humans, the report said, but DNA from the 10th and oldest fossil, a 62,000-year-old anatomically modern man from southeastern Australia’s Lake Mungo region, was genetically unrelated to the others.
This finding potentially has great significance, because it disputes the view that modern Homo sapiens migrated out of Africa 100,000 years ago and “replaced” archaic species throughout the world.
Instead, the Lake Mungo fossil suggests at least one anatomically modern lineage that has no relationship to contemporary humans, the Australian team said. The fossil appears to belong to an independent genetic line that is now extinct.
This finding would lend support to the “multiregional” school, which acknowledges that human ancestors spread out of Africa about 1.5 million years ago, but that modern humans evolved gradually in different areas.
"A single migration out of Africa is simplistic,” said team member and molecular biologist James Peacock of the Commonwealth Scientific and Industrial Research Organization. “There would be no reason for us to think that Lake Mungo man wasn’t one of the precursors of modern aborigines just because his mitochondrial DNA sequence has become extinct.”
The dispute between replacement theorists and multiregionalists has arisen over the last decade with the growing use of DNA analysis in genetics. Mitochondria are cell components containing genetic material — DNA — that enable scientists to trace the lineage of plants and animals from generation to generation. The mitochondrial DNA in all contemporary humans is closely related, despite what appear to be radical differences in race, coloring and body type.
Working backward in time, geneticists reached the conclusion that “modern humans” originated from common ancestors who left Africa about 100,000 years ago, and shoved aside whatever human ancestors they found elsewhere.
“Some of my colleagues call this the ‘killer Africans’ theory,” said team member Alan Thorne, an anthropologist at the Research School of Pacific and Asian Studies at the Australian National University.
This view appeared to have been borne out last year when scientists reported that DNA recovered from three Neanderthal fossils did not match contemporary DNA, indicating that Neanderthals were a different species rendered extinct about 30,000 years ago during the Ice Age, as modern humans swept across Europe.
Modern humans crossed over to Australia from New Guinea over an Ice Age land bridge, Thorne explained, and although the Lake Mungo fossil is the oldest known human remains on the continent, they were found more than 2,000 miles from the northern coast, an indication that humans had been in Australia considerably longer.
More important for the debate on human origins, the Lake Mungo fossil is “gracile,” or anatomically modern, lacking the broad, ridged foreheads and heavy bone structure of Neanderthals and other “robust” humans.
Four of the Australian fossils, however, were robust, even though their DNA was clearly related to that of contemporary humans. Finally, Peacock said, sequences from the Lake Mungo DNA have been identified in the nuclei of contemporary humans, suggesting there was reproductive contact, rather than simply replacement, between the extinct lineage and the ancestors of contemporary humans.
MORE STUDY NEEDED
“This study puts the Neanderthal study in perspective,” said John H. Relethford, an anthropologist at the State University of New York at Oneonta who wrote a commentary to accompany the Australian research. “It doesn’t mean that the out-of-Africa theory is wrong, but it chips away at it.”
New York University molecular anthropologist Todd Disotell, a leading proponent of the replacement theory, said the Australian study could be “a very significant result, if the analysis holds up,” but “I need to see some more detail.”
Disotell noted that the DNA of “over 10,000 people have now been sampled,” and the results “are consistent with the recent replacement hypothesis.” By contrast, “ancient DNA is really hard to work with. Did they do this right? That is the big question.”
© 2001 The Washington Post Company
|Human Migration Theory Disputed |
By PAUL RECER
AP Science Writer
January 12, 2001 - Modern humans likely arose from small groups that journeyed from continent to continent, not in a single migration from Africa, anthropologists say.
These individual groups probably intermingled with archaic humans such as the Neanderthal, said the researchers, who analyzed ancient skulls from around the world.
They said that distinctive features in ancient skulls, some dating to more than 200,000 years, suggest modern humans descended independently from common ancestors that lived on nearly every continent and mingled with earlier human types.
"There was no single wave of modern humans out of Africa,'' said Milford H. Wolpoff, a University of Michigan anthropologist and co-author of the study, published in Friday's edition of the journal Science.
Modern humans did originate in Africa, Wolpoff said, but they migrated in small groups over thousands of years and journeyed to Asia, Europe and even as far as Australia.
"It was not a single wave,'' he said. "It was more like a leaky faucet. They moved out in dribbles.''
This is contrary to the Eve theory, which holds that modern humans evolved in Africa and moved into the rest of the world in a singular movement of perhaps 10,000 people. Once on the other continents, the theory holds, the moderns supplanted the existing more ancient humans, such as the Neanderthal.
But Wolpoff and his co-authors said that skulls dated 25,000 to 30,000 years from Europe and from Australia share strong characteristics of 40,000 to 200,000-year-old archaic human skulls found in Europe, Indonesia, and Africa.
The more recent skulls from Europe, for instance, showed clear evidence of a Neanderthal influence, along with features of the early modern humans that evolved in Africa. Early modern human skulls from Australia had similarities to the more ancient skulls from Indonesia.
Wolpoff said this suggests modern humans dribbled out of Africa in small numbers and migrated to distant lands where they mingled with a more ancient human type that already lived in those places.
Eventually, he said, the superior genes of modern humans dominated the species through natural selection and the clearly identifiable archaic humans, such as the Neanderthal, disappeared.
"The Neanderthal disappeared as a result of interbreeding,'' Wolpoff said.
Traces of those archaic humans survive still, in the genes of modern humans, said John Hawks, University of Utah anthropologist and co-author of the study. And these genes produce distinctive markings on modern human skulls.
"There are still Neanderthals today and they are us,'' Hawks said in a statement released by the University of Utah. "People of European descent are also people of Neanderthal descent.''
The conclusion is controversial, and another University of Utah anthropologist, Henry Harpending, said he is unconvinced.
"The genetic evidence is unequivocal in support of the idea that we are all descended from a small group of Africans within the last 100,000 years,'' Harpending said in a statement. "There is no Neanderthal in us.''
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