Interesting Science

Archeologists from Yale and the University of Leicester have identified an ancient solar observatory at Chankillo (alt. Chanquillo), Peru as the oldest in the Americas with alignments covering the entire solar year, according to an article in the March 2 (2007) issue of Science [1].

This post includes a podcast and video

The fortified stone temple at Chankillo. (SAN)

Recorded accounts from the 16th century A.D. detail practices of state-regulated sun worship during Inca times, and related social and cosmological beliefs. These speak of towers being used to mark the rising or setting position of the sun at certain times in the year, but no trace of the towers has ever been found. This paper reports the earliest structures that support those writings.

At Chankillo, not only were there towers marking the sun's position throughout the year, but they remain in place, and the site was constructed much earlier - in approximately the 4th century B.C.

"Archaeological research in Peru is constantly pushing back the origins of civilization in the Americas," said Ivan Ghezzi, a graduate student in the department of Anthropology at Yale University and lead author of the paper. "In this case, the 2,300 year old solar observatory at Chankillo is the earliest such structure identified and unlike all other sites contains alignments that cover the entire solar year. It predates the European conquests by 1,800 years and even precedes, by about 500 years, the monuments of similar purpose constructed by the Mayans in Central America."

Chankillo is a large ceremonial center covering several square kilometers in the costal Peruvian desert. It was better known in the past for a heavily fortified hilltop structure with massive walls, restricted gates, and parapets. For many years, there has been a controversy as to whether this part of Chankillo was a fort or a ceremonial center. But the purpose of a 300meter long line of Thirteen Towers lying along a small hill nearby had remained a mystery..

The new evidence now identifies it as a solar observatory. When viewed from two specially constructed observing points, the thirteen towers are strikingly visible on the horizon, resembling large prehistoric teeth. Around the observing points are spaces where artifacts indicate that ritual gatherings were held.

The current report offers strong evidence for an additional use of the site at Chankillo - as a solar observatory. It is remarkable as the earliest known complete solar observatory in the Americas that defines all the major aspects of the solar year.

"Focusing on the Andes and the Incan empire, we have known for decades from archeological artifacts and documents that they practiced what is called solar horizon astronomy, which uses the rising and setting positions of the sun in the horizon to determine the time of the year," said Ghezzi. "We knew that Inca practices of astronomy were very sophisticated and that they used buildings as a form of "landscape timekeeping" to mark the positions of the sun on key dates of the year, but we did not know that these practices were so old."

According to archival texts, "sun pillars" standing on the horizon near Cusco were used to mark planting times and regulate seasonal observances, but have vanished and their precise location remains unknown. In this report, the model of Inca astronomy, based almost exclusively in the texts, is fleshed out with a wealth of archaeological and archaeoastronomical evidence.

Ghezzi was originally working at the site as a Yale graduate student conducting thesis work on ancient warfare in the region, with a focus on the fortress at the site.

Noting the configuration of 13 monuments, in 2001, Ghezzi wondered about a proposed relationship to astronomy. "Since the 19th century there was speculation that the 13-tower array could be solar or lunar demarcation - but no one followed up on it," Ghezzi said. "We were there. We had extraordinary support from the Peruvian Government, Earthwatch and Yale University. So we said, 'Let's study it while we are here!'"

To his great surprise, within hours they had measurements indicating that one tower aligned with the June solstice and another with the December solstice. But, it took several years of fieldwork to date the structures and demonstrate the intentionality of the alignments. In 2005, Ghezzi connected with co-author Clive Ruggles, a leading British authority on archeoastronomy. Ruggles was immediately impressed with the monument structures.

"I am used to being disappointed when visiting places people claim to be ancient astronomical observatories." said Ruggles. "Since everything must point somewhere and there are a great many promising astronomical targets, the evidence - when you look at it objectively - turns out all too often to be completely unconvincing."

"Chankillo, on the other hand, provided a complete set of horizon markers - the Thirteen Towers - and two unique and indisputable observation points," Ruggles said. "The fact that, as seen from these two points, the towers just span the solar rising and setting arcs provides the clearest possible indication that they were built specifically to facilitate sunrise and sunset observations throughout the seasonal year."

What they found at Chankillo was much more than the archival records had indicated. "Chankillo reflects well-developed astronomical principles, which suggests the original forms of astronomy must be quite older," said Ghezzi, who is also the Director of Archaeology of the National Institute of Culture in Lima, Peru.

The researchers also knew that Inca astronomical practices in much later times were intimately linked to the political operations of the Inca king, who considered himself an offspring of the sun. Finding this observatory revealed a much older precursor where calendrical observances may well have helped to support the social and political hierarchy. They suggest that this is the earliest unequivocal evidence, not only in the Andes but in all the Americas, of a monument built to track the movement of the sun throughout the year as part of a cultural landscape.

According to the authors, these monuments were statements about how the society was organized; about who had power, and who did not. The people who controlled these monuments "controlled" the movement of the sun. The authors pose that this knowledge could have been translated into the very powerful political and ideological statement, "See, I control the sun!"

"This study brings a new significance to an old site," said Richard Burger, Chairman of Archeological Studies at Yale and Ghezzi's graduate mentor. "It is a wonderful discovery and an important milestone in Andean observations of this site that people have been arguing over for a hundred years."

"Chankillo is one of the most exciting archaeo-astronomical sites I have come across," said Ruggles. "It seems extraordinary that an ancient astronomical device as clear as this could have remained undiscovered for so long."

Source: Yale University PR "Peruvian Citadel is Site of Earliest Ancient Solar Observatory in the Americas" March 1 2007

The science-writer Charles C. Mann has written an article about the solar observatory - listen to him being interviewed in a Science magazine podcast

[Photo Courtesy of Peru's National Aerophotographic Service (SAN)]

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[1] Based on the paper:

Chankillo: A 2300-Year-Old Solar Observatory in Coastal Peru
Ivan Ghezzi and Clive Ruggles

Science 2 March 2007:
Vol. 315. no. 5816, pp. 1239 - 1243
DOI: 10.1126/science.1136415

The Thirteen Towers of Chankillo run north to south along a low ridge within a fourth-century B.C.E. ceremonial complex in north coastal Peru. From evident observing points within the adjacent buildings to the west and east, they formed an artificial toothed horizon that spanned - almost exactly - the annual rising and setting arcs of the Sun. The Chankillo towers thus provide evidence of early solar horizon observations and of the existence of sophisticated Sun cults, preceding the Sun pillars of Incaic Cusco by almost two millennia.

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Video of the ruins at Chankillo/Chanquillo - the shot of the Thirteen Towers is very brief so use of the 'pause button' is recommended:

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Technorati: chankillo, chanquillo, peru, solar, observatory, sun, archaeology, astronomy, temple, podcast, video, inca, mayans, anthropology, thirteen, towers, andes, americas, civilization, earthwatch, science, solstice, culture, lima, yale, university

Permanent Link posted by John Latter @ 12:08 AM 1 comments

Experts say further study of past pandemics key to preparedness

Scientists and public health officials, wary that the H5N1 avian influenza virus could trigger an influenza pandemic, have looked to past pandemics, including the 1918 "Spanish Flu," for insight into pandemic planning. However, in a Journal of Infectious Diseases review article now posted online [1], David M. Morens (also co-author of "Influenza Revisited"), M.D., and Anthony S. Fauci, M.D., of the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, conclude that studies of the 1918 influenza pandemic, which killed some 50 to 100 million people around the globe, have so far raised more questions than they answer.

"Today, nearly a century after the 1918 influenza pandemic, its mysteries remain largely unexplained," says Dr. Fauci, NIAID director. "Much work remains to be done, by scientists as well as by historians and other scholars, with regard to the many unanswered questions surrounding this historic pandemic. These studies must be part of our preparedness efforts as we face the prospect of a future influenza pandemic."

Dr. Morens adds, "In addition to ongoing laboratory studies, we feel that much can be learned from examining the vast scientific literature related to the 1918 influenza pandemic and previous influenza pandemics. A treasure trove of journal articles and other materials exists in many languages that can be mined for novel information with practical applications relevant to the threat of pandemic influenza we face."

In their article, Drs. Morens and Fauci review several topics, including the origins of the 1918 pandemic influenza virus (see the New York Times' "Experts Unlock Clues to Spread of 1918 Flu Virus" - may require free registration), the excess mortality of the pandemic, the predilection to kill the young and healthy, the lower-than-expected mortality among the elderly, and the cyclicity of influenza pandemics over the past 100 years. Such topics are relevant today as highly pathogenic H5N1 avian influenza A viruses have spread from Asia to the Middle East, Europe and Africa.

One of the great unsolved mysteries surrounding the 1918 pandemic is why it tended to kill the young and healthy. Unlike yearly influenza epidemics, in which death rates are highest among infants, the elderly and those with chronic health conditions, the 1918 influenza pandemic took its greatest toll on healthy adults between the ages of 20 and 40. One possible explanation, supported by recent studies in mice with a reconstructed version of the 1918 virus, is that an over-responsive immune system may release a "cytokine storm," or excessive amount of immune system proteins that trigger inflammation and harm the patient in the process. Of note, most deaths among humans infected with the H5N1 avian influenza virus have occurred in individuals under the age of 40. However, as the authors point out, it is not yet known whether there is a higher percentage of young people in the affected populations compared to older people, whether younger people are more susceptible to infection or whether they have more exposure to infected birds.

Highly pathogenic H5N1 influenza viruses have primarily infected wild birds and domestic poultry populations in dozens of countries, although at least 275 people have been infected and 167 have died. As Drs. Morens and Fauci point out, the H1N1 virus that caused the 1918 pandemic appears to be avian in origin, but the host source of the 1918 virus has never been identified. Furthermore, no major disease outbreaks among birds were documented immediately before the 1918 pandemic. They suggest that an avian influenza strain could have been hidden in an obscure ecological niche, and the pandemic strain arose by the genetic adaptation of that avian virus to a new human host.

"The more we learn about influenza A viruses and what they can do to maintain their deadly relationship with the human species, the more remarkable they seem," says Dr. Morens. "The challenge for us is to learn as much about influenza viruses as they have already 'learned' about us."

[Image: 1918 Public Notice]

Drs. Morens and Fauci also discuss the high number of deaths associated with the 1918 pandemic and the disease process, based on clinical and autopsy studies published between 1918 and 1922. Most pandemic deaths were associated with either an aggressive bronchopneumonia, in which bacteria could be cultivated from lung tissue at autopsy, or with a severe acute respiratory distress-like syndrome (ARDS) characterized by blue-grey facial discoloration and excessive fluid in the lungs. In neither case is it known whether most deaths were caused by a secondary bacterial infection or a primary viral infection. They propose that the many excess deaths that occurred during the 1918 influenza pandemic resulted from a disease process that began with a severe acute viral infection that spread down the respiratory tree causing severe tissue damage, which was often followed by secondary bacterial invasion. More definitive answers regarding the causes of deaths due to the "Spanish Flu" may require a comprehensive re-examination of the 1918 autopsy series, they note.

If a pandemic with similar characteristics were to occur in the near future, Drs. Morens and Fauci predict that the relative number of deaths would be substantially lower than that which occurred in 1918.

"Almost all 'then-versus now' comparisons in theory are encouraging," they write. "In 2007 public health is much more advanced, with better prevention knowledge, good influenza surveillance, more trained personnel at all levels, well-established prevention programs featuring annual vaccination with up-to-date influenza and pneumococcal vaccines, and a national and international prevention infrastructure." In addition, two classes of antiviral drugs are currently available, as well as antibiotics effective against bacteria that cause influenza-associated pneumonia.

The most difficult challenge in mitigating the effects of a severe pandemic today would be to ensure access to medical care and resources, they note. Hospitals, medical personnel and drug suppliers could be overwhelmed with huge demands for services, medicines and vaccines, a situation that would be exacerbated in less developed countries and impoverished regions.

Drs. Fauci and Morens conclude that the best hope for the future lies in developing and stockpiling more broadly protective influenza vaccines. In the meantime, prevention efforts should be directed towards logistical planning, increased surveillance, the development of medical countermeasures, an improved understanding of pandemic risks, and an aggressive and broad research agenda.

Source (Adapted): National Institute of Allergy and Infectious Diseases PR "Review of 1918 pandemic flu studies offers more questions than answers" February 28 2007

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[1] Based on the paper:

The 1918 Influenza Pandemic: Insights for the 21st Century

David M. Morens and Anthony S. Fauci

The Journal of Infectious Diseases 2007;195:000
This article is in the public domain, and no copyright is claimed.
0022-1899/2007/19507-00XX
DOI: 10.1086/511989 (2007).

The 1918 - 1919 H1N1 influenza pandemic was among the most deadly events in recorded human history, killing an estimated 50 - 100 million persons. Because recent H5N1 avian epizootics have been associated with sporadic human fatalities, concern has been raised that a new pandemic, as fatal as the pandemic of 1918, or more so, could be developing. Understanding the events and experiences of 1918 is thus of great importance. However, despite the genetic sequencing of the entire genome of the 1918 virus, many questions about the 1918 pandemic remain. In this review we address several of these questions, concerning pandemic-virus origin, unusual epidemiologic features, and the causes and demographic patterns of fatality. That none of these questions can yet be fully answered points to the need for continued pandemic vigilance, basic and applied research, and pandemic preparedness planning that emphasizes prevention, containment, and treatment with antiviral medications and hospital-based intensive care.

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Breaking News:

The body of Sir Mark Sykes (1879 - 1919), 6th Baronet of Sledmere House near Driffield, Yorkshire (UK), is to be exhumed in the hope of discovering clues about the nature of the H5N1 bird flu virus.

Sir Mark - once tipped to be a future British Prime Minister and a victim of the Spanish flu pandemic - died in Paris in 1919 while working on the Versailles Peace Conference and is thought to have been buried in a lead-lined coffin.

See the BBC news report "Dead aristocrat's hidden flu clue" and a video report of experts using ground penetrating radar to survey Sir Mark's grave (includes comments from virologist Professor John Oxford and 102-year-old Florence Herrington who survived the flu).

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Technorati: influenza, pandemic, spanish, flu, h5n1, avian, virus, 1918, allergy, infectious, diseases, genetic, adaptation, immune system, wild, birds, domestic, poultry, strain, ards, treatment, hospital, care, deaths, autopsy

Permanent Link posted by John Latter @ 7:25 PM 1 comments

While NASA and the European Space Agency (ESA) focus on Mars rovers and future missions to search for life on the Red Planet, a determined core of scientists is lobbying for equal attention to a place they feel is just as likely to harbor life - Jupiter's icy moon Europa.

"Because of the well-supported presence of water ice on Europa and the probability that there are briny oceans, Europa has to be a major target for the search for life in the solar system," said paleobiologist Jere H. Lipps, professor of integrative biology at the University of California, Berkeley. "Many of us are proposing that there is habitat there where we can expect to find evidence of life."

Lipps took up the issue with three other scientists on a panel Sunday (February 18 2007) at the annual meeting of the American Association for the Advancement of Science (AAAS) in San Francisco. The group, organized by Lipps, reviewed what is known about Europa and focused on the problems that need to be solved before undertaking a search for life on the frozen moon.

The reddish ovals in the center of this image may be areas where water from Europa's underground ocean upwelled and froze on the surface. (Courtesy of Galileo Project, NASA)

With years of experience studying life in the Antarctic and Arctic ice, Lipps, a member of the campus's Museum of Paleontology, knows the bizarre places organisms can thrive, and the unique processes that can bring life from deep under the ice to the surface. This is relevant because Europa, the third largest of Jupiter's moons, is thought to have a thick ocean of water overlain by a layer of ice that could be miles thick.

"Life thrives in ice, it doesn't mind at all," said Lipps, whose interest in single-celled organisms drew him to consider the possibility of life on other planets, which is likely to be more akin to bacteria than to humans. "In Antarctica, every phylum of algae, protozoan, bacteria and animal lives in the ice, many of them in brine channels that don't freeze."

Bacteria, diatoms, clams, snails, sponges and even fish larvae live under the ice shelves, yet often appear on the surface because of upheavals in the ice.

Similarly, photos taken by the Galileo spacecraft reveal a highly fractured ice surface on Europa with domes and ridges and uptilted ice rafts indicating that the surface has been reworked in a way that could have brought organisms living under the ice to the surface. There's also evidence that liquid water has welled up through cracks and refrozen in smooth lakes.

Using his knowledge of Earth's polar environments gained over 12 years working in Antarctica, including on the Ross Ice Shelf, Lipps proposed 25 likely habitats for life on Europa in a 2005 paper [1] in the journal Icarus. Any exploration of the moon should examine these sites in detail, he said.

Lipps does not assume that life on Europa would be like life on Earth. However, he said, "The strategy of seeking and exploring habitats, rather than the life itself, should provide a most powerful search strategy," as well as guiding instrument development and deployment programs.

Lipps argues that the environments of life, the energy for life and all the chemicals needed for life, including oxygen, have been present on the moon for a long time, probably at least 60 million years, judging from crater counts on the moon's surface. Scientists suspect that liquid water near the freezing point, zero degrees Celsius (32 degrees Fahrenheit), is able to exist on Europa because of heat generated by tidal friction between the moon and its immense neighbor, the planet Jupiter.

"Based on analogy with Earth's polar seas, Europan life may occur in many habitats: on soft and rocky bottoms at the ocean's floor, associated with hydrothermal vents on the floor of the oceans, at different levels in the water column as plankton and nekton, and in and on the ice cover itself," Lipps noted. "Some of these might contain complex associations of life forms, including both micro- and macroscopic forms and consumers and predators."

Just as turnover of Antarctic ice brings organisms to the top, so would the dynamic oceanographic and geologic processes evident on Europa's icy surface expose these life forms at the surface, where they could be detected by orbiting spacecraft or roving landers.

"This is a paleontological search strategy, which is what I do," he said. "If I want to collect fossils in Nevada, I get a map and look for likely spots, like rock outcroppings, where fossils will be found. Ice turned on its edge is just a geologic outcrop to me - let's go there and see if we can find evidence of past or present life."

Surface sites that might contain habitats with life or fossils include the areas of refrozen ocean, chaotic terrains with tilted and rotated blocks of ice, the ridges and rills associated with fissures, low areas where water may have collected, and "dirty" ice that may include material and organisms floated to the surface by ice formed on the bottom of the ocean or gouged by moving ice, as well as a variety of habitats in the ice itself.

Lipps noted, too, that while radiation at the surface could be intense enough to kill any Earth-like life, it would not penetrate more than a meter or two, so that many cracks, tubes, caves, and overhangs might exist in the surface ice that could be inhabited by life forms. Ices of different ages could provide an evolutionary look at life on the moon.

"A sampling strategy for life and its history on Europa should include paleontological, molecular biological, and volatile and organic chemical objectives that would clearly document the present and/or former existence of life on Europa," he said. He also urged detailed imaging of surface features, even at the microscopic level, since "the most exciting and convincing evidence for the general public would be an image of a life form."

Lipps said that if we start planning now, we could perhaps have a spacecraft on Europa in 15 years.

"We'd like a mission to Europa, and we've pointed out the likely places for life," Lipps said. "It's now up to the engineers, and to NASA decision-makers and funders, to determine how to get there."

Other scientists speaking at the symposium, "Enigmatic Europa: Understanding Jupiter's Icy Moon," were Ronald Greeley of Arizona State University in Tempe; Bill McKinnon [2] of Washington University in St. Louis, Mo.; and Louise Prockter of Johns Hopkins University in Baltimore, Md.

Source: University of California, Berkeley PR "Looking for life on Jupiter's icy moon Europa" February 22 2007 [Astrobiology, Astronomy]

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[1] Habitats and taphonomy of Europa

Jere H. Lipps and Sarah Rieboldt

Icarus
Volume 177, Issue 2 , October 2005, Pages 515-527
Europa Icy Shell
doi:10.1016/j.icarus.2005.04.010

Abstract

Jupiter's moon Europa possesses an icy shell kilometers thick that may overlie a briny ocean. The inferred presence of water, tidal and volcanic energy, and nutrients suggests that Europa is potentially inhabited by some kind of life; indeed Europa is a primary target in the search for life in the Solar System although no evidence yet exists for any kind of life. The thickness of the icy crust would impose limits on life, but at least 15 broad kinds of habitats seem possible for Europa. They include several on the sea floor, at least 3 in the water column, and many in the ice itself. All of these habitats are in, or could be transported to, the icy shell where they could be exposed by geologic activity or impacts so they might be explored from the surface or orbit by future planetary missions. Taphonomic processes that transport, preserve, and expose habitats include buoyant ice removing bottom habitats and sediment to the underside of the ice, water currents depositing components of water column habitats on the ice bottom, cryovolcanoes depositing water on the surface, tidal pumping bringing water column and ice habitats to the near-surface ice, and subice freezing and diapiric action incorporating water column and bottom ice habitats into the lower parts of the icy shell. The preserved habitats could be exposed at or near the surface of Europa chiefly in newly-formed ice, tilted or rotated ice blocks, ridge debris, surface deposits, fault scarps, the sides of domes and pits, and impact craters and ejecta. Future exploration of Europa for life must consider careful targeting of sites where habitats are most likely preserved or exist close to the surface.

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[2] Video in which Bill McKinnon argues the case for Europa: "Europa probably has the best chance to have life":

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Technorati: nasa, esa, mars, rovers, search, life, planets, jupiter, europa, moon, water, ice, solar system, biology, aaas, antarctic, arctic, galileo, project, paleontology, algae, bacteria, spacecraft, ross, shelf, sea, hydrothermal, vents, ocean, astrobiology, astronomy, video

Permanent Link posted by John Latter @ 9:30 AM 0 comments

The belief that the Clovis People were the first to populate North America some 11,500 years ago has been widely challenged in recent years, and a Texas A and M University anthropologist has found [new] evidence he says could be the final nail in the coffin for the Clovis-first model.

Michael Waters, director of the Center for the Study of the First Americans at Texas A and M, is the lead author of the paper "Redefining the Age of Clovis: Implications for the Peopling of the Americas," [1] which appeared in the February 23 2007 issue of Science.

Waters' paper revises the original dates for the Clovis time period, suggesting that humans likely inhabited the Americas before Clovis, who have long been considered to be the first inhabitants of the New World.

"It was always argued that Clovis represented the first people who came to the Americas," Waters says. "The new dating that we did indicates that the Clovis Complex ranges from 11,050 to 10,900 radiocarbon years before the present."

"Slowly but surely, archaeologists have been questioning whether Clovis represents the earliest people to enter the Americas."

To properly understand the age of Clovis, Waters and co-author Thomas Stafford of Stafford Research Laboratories in Colorado tested samples from various Clovis sites in an effort to re-date some of what Waters says were poorly dated sites.

Because of technological advances, Waters says that he and Stafford were able to more precisely pinpoint the dates for some of the more than 25 dated Clovis sites that were excavated in North America. "Many of these radiocarbon dates were run back in the 1960s and 1970s when radiocarbon technology wasn't what it is today," says Waters. "Many of the dates obtained from these sites had ranges on them of plus or minus 250 years. We can now get to plus or minus 30 years."

What Waters and Stafford found when they did their testing were radiocarbon dates that showed the Clovis time range wasn't as long as previously had been thought. Their tests placed the Clovis time frame between 11,050 radiocarbon years before present to approximately 10,800 radiocarbon years before present.

"It was a surprise," Waters says of the results. "And I think people are going to be surprised by the dates."

Waters says those dates show that Clovis was no more than 200 to 400 calendar years long, making it almost impossible for the Clovis people to spread as far as previously thought in such a short time span. They would, at most, have had to be prehistoric jet-setters to cover the ground in this amount of time.

"Once you realize that the Clovis Complex dates much younger than previously thought and that Clovis has a much shorter duration than we thought, you have to ask how could people, in such a short period of time, reach the tip of South America." Waters says. "It doesn't make any kind of anthropological sense that these people could have been moving that fast, nor would they have wanted to move that fast. And it seems highly unlikely, given 20 generations, they could have made it that far that quickly."

To re-date the sites, Waters requested samples for dating from different researchers who had excavated Clovis sites. He then sent the radiocarbon samples to Stafford who put them through a process where the bone is dissolved and bone collagen is extracted.

The collagen was put in a molecular sieve where it worked its way down through the sieve. Once this was complete, Stafford was left with purified amino acids from the bone. The highly chemically-pure sample was processed into a target and dated using an atomic accelerator.

The revised ages that Waters and Stafford obtained overlap dates from a number of North American sites that are technologically and culturally not Clovis sites, further bringing into question whether the Clovis People were the first humans in the Americas.

"The long-range implications of our study is that it will get scientists looking for pre-Clovis evidence with a lot more vigor and thinking differently about Clovis," Waters says. "This will force us to develop a new model to explain the peopling of the Americas."

Source (Adapted): Texas A and M University PR "Michael Waters' Clovis People Study Is Cover Story For Science" February 22 2007

[Anthropology, Archaeology, Paleo-Indians]

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Based on the paper:

Redefining the Age of Clovis: Implications for the Peopling of the Americas

Michael R. Waters and Thomas W. Stafford, Jr.

Science 23 February 2007:
Vol. 315. no. 5815, pp. 1122 - 1126
DOI: 10.1126/science.1137166

The Clovis complex is considered to be the oldest unequivocal evidence of humans in the Americas, dating between 11,500 and 10,900 radiocarbon years before the present (14C yr B.P.). Adjusted 14C dates and a reevaluation of the existing Clovis date record revise the Clovis time range to 11,050 to 10,800 14C yr B.P. In as few as 200 calendar years, Clovis technology originated and spread throughout North America. The revised age range for Clovis overlaps non-Clovis sites in North and South America. This and other evidence imply that humans already lived in the Americas before Clovis.

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Technorati: clovis, people, north america, texas, university, age, complex, sites, radiocarbon dating, prehistoric, pre-clovis, paleo, indians, anthropology, archaeology, science, technology

Permanent Link posted by John Latter @ 7:30 PM 0 comments