8/30/2019 By Lizzie Wade  Ancient people apparently followed rivers more than 500 kilometers inland to Cooper's Ferry in western Idaho. About 16,000 years ago, on the banks of a river in western Idaho, people kindled fires, shaped stone blades and spearpoints, and butchered large mammals. All were routine activities in prehistory, but their legacy today is anything but. The charcoal and bone left at that ancient site, now called Cooper’s Ferry, are some 16,000 years old—the oldest radiocarbon-dated record of human presence in North America, according to work reported this week in Science. The findings do more than add a few centuries to the timeline of people in the Americas. They also shore up a new picture of how humans first arrived, by showing that people lived at Cooper’s Ferry more than 1 millennium before melting glaciers opened an ice-free corridor through Canada about 14,800 years ago. That implies the first people in the Americas must have come by sea, moving rapidly down the Pacific coast and up rivers. The dates from Cooper’s Ferry “fit really nicely with the [coastal] model that we’re increasingly getting a consensus on from genetics and archaeology,” says Jennifer Raff, a geneticist at the University of Kansas in Lawrence who studies the peopling of the Americas.  Academic Enrichment Programs for 1st - 8th Grade Students Join Us To Be Elite Tel: 571-217-2357  SAT/PSAT, AP Calculus/AP Physics, College Essay, TJ Prep The Clovis people, big game hunters who made characteristic stone tools dated to about 13,000 years ago, were once thought to have been the first to reach the Americas, presumably through the ice-free corridor. But a handful of earlier sites have persuaded many researchers that the coastal route is more likely. Archaeologists have questioned the signs of occupation at some putative pre-Clovis sites, but the stone tools and dating at Cooper’s Ferry pass the test with flying colors, says David Meltzer, an archaeologist at Southern Methodist University in Dallas, Texas. “It’s pre-Clovis. I’m convinced.” Over 10 years of excavations, the Cooper’s Ferry team uncovered dozens of stone spear points, blades, and multipurpose tools called bifaces, as well as hundreds of pieces of debris from their manufacture. Although the site is near the Salmon River, most of the ancient bones belonged to mammals, including extinct horses. The team also found a hearth and pits dug by the site’s ancient residents, containing stone artifacts and animal bones. Radiocarbon dates on the charcoal and bone are as old as 15,500 years. In North America, few tree ring records can precisely calibrate such early radiocarbon dates, but a state-of-the-art probabilistic model placed the start of the occupation at between 16,560 and 15,280 years. “I may not think it goes back to 16,000 years ago, but I surely can believe it goes back 15,000 years,” says Michael Waters, an archaeologist at Texas A&M University in College Station. The only rival to Cooper’s Ferry as the oldest site in North America is the Gault site in Texas. Researchers dated that site to about 16,000 years ago by optical luminescence, a method with larger error bars than radiocarbon dating. It’s easy to see how seafaring people might have reached Cooper’s Ferry, says Loren Davis, an archaeologist at Oregon State University in Corvallis who led the excavations. Although the site is more than 500 kilometers from the coast, the Salmon, Snake, and Columbia rivers link it to the sea. “As people come down the coast, the first left-hand turn to get south of the ice comes up the Columbia River Basin,” Davis says. “It’s the first off-ramp.”  A 6-centimeter blade is among the oldest at an Idaho site. The area is now federal land but was long occupied by the Nez Perce Tribe, or the Niimíipuu. They know Cooper’s Ferry as Nipéhe, an ancient village founded by a young couple after a flood destroyed their previous home, says Nakia Williamson, the tribe’s director of cultural resources. “Our stories already tell us how long we’ve been here. … This [study] only reaffirms that,” Williamson says. He hopes the excavations—in which Nez Perce archaeologists and interns participated—will help others recognize the deep ties the Nez Perce have to their ancestral lands. “This is not just something that happened 16,000 years ago. It’s something that is still important to us today,” he says.  APLUS教学中心 | 一对一辅导服务中心 | 申请咨询顾问中心  Cooper’s Ferry may also offer a glimpse of the tools carried by the first arrivals to the Americas. Many of the spearpoints found there belong to the western stemmed point tradition, smaller—about the size of a pinkie—and lighter than the hefty Clovis points. Such tools have been found at early sites from British Columbia to Peru, and as far inland as Texas. Similar points are known from Japan from about 16,000 to 13,000 years ago, Davis says. He and others argue that western stemmed points are emerging as the best markers of the first people to arrive in the Americas, and that they carried the tradition with them from Asia. But Meltzer isn’t convinced the western stemmed tradition conclusively predates Clovis or represents a coastal connection around the Pacific Rim. There are plenty of sites in Siberia in Russia without the technology, he says, and the complete points at Cooper’s Ferry are almost the same age as Clovis. (The site’s oldest tools are blades, bifaces, and fragments of points, fashioned with the same methods used to make western stemmed points.) Just as archaeology puts one debate about stone tools in the Americas to rest, it could be gearing up for the next one.  (World Journal) 記者胡玉立  科學家在愛達荷州西部庫珀渡輪遺址，發現了人類早在1萬6000年前居住當地的古文物，為當時第一批美洲人順著太平洋沿岸來到未來新家，提供最新證據。圖為庫珀渡輪峽谷。(美聯社)  科學家在愛達荷州西部庫珀渡輪遺址，發現了人類早在1萬6000年前居住當地的古文物，為當時第一批美洲人順著太平洋沿岸來到未來新家，提供最新證據。圖為科學家在庫珀渡輪峽谷進行測量。(美聯社) 科學家在愛達荷州發現一批可以證明人類早在1萬6000年前居住當地的古文物，為當時第一批美洲人順著太平洋沿岸來到未來新家，提供最新證據。俄勒岡州立大學研究負責人羅倫．戴維斯（Loren Davis）表示，這項發現也透露：日本可能是這批移民的起源或影響因素。 「科學」雜誌29日報導戴維斯及其同僚在愛達荷州西部「庫珀渡輪」（Cooper’s Ferry）遺址挖掘的情況。其他專家對調查結果的意涵及到底有多古老，看法分歧。在有關新大陸早期人類議題方面，一直存在爭議。這樣的反應並非罕見。  Award-Winning After-School Math Program for K-12 Students  Offering serious and challenging mathematics to intellectually gifted students 戴維斯研究團隊在遺址最古老的區域發現43塊薄片，這些薄片應該是在製作工具過程中從石頭切下來；這種作法和年代較近的遺址區域類似。另外還發現四塊薄片，曾被修整用來切割或刮擦，還找到一些吃完丟棄的骨頭。 分析顯示，該遺址年代介於據今1萬5280至1萬6560年，大約是1萬6000年前。隨著時間推演，此遺址被重複佔據使用。研究人員說，這樣的發現涉及第一批美洲人如何到來的爭論議題。 傳統看法是，美洲人遷徙，始於越過一個從西伯利亞延伸到阿拉斯加、如今已被淹沒的白令陸橋（Beringia）地塊；之後的向南遷移曾被加拿大巨大冰原阻擋，但後來冰原裂出縫隙，人們得以穿過所謂的「無冰走廊」。 Principal,  Licensed in MD, VA, DC, PA , DE, NC, SC, FL WeChat ID: sunnychenyuqing NMLS # 1220187 但近年來，科學家發現早期人類生活在美洲的跡象，認為早在無冰走廊出現前，美洲已有人跡；可能是步行或乘船沿太平洋而來。 戴維斯說，他的論文顯示人們早在無冰走廊於1萬4800年前打開之前，就已在愛達荷州那裡居住。最好的解釋是「他們從海岸下來，在冰原以南左轉，然後來到哥倫比亞河流域。」 戴維斯指出，該遺址還發現一種類似日本北海道年代類似的石製抛擲武器尖端。當時北海道仍是廣大土地的一部分，可以支持第一批美洲移民開始前往美洲地區發展的理論。他說，從北海道地區遷徙，可能繞過白令陸橋南部海岸，然後沿太平洋向南行進。 8/30/2019 By KIONA N. SMITH  Lasers help record the precise position of each artifact on the site. Evidence from the Cooper's Ferry archaeological site in Western Idaho shows that people lived in the Columbia River Basin around 16,000 years ago. That's well before a corridor between ice sheets opened up, clearing an inland route south from the Bering land bridge. That suggests that people migrated south along the Pacific coast. Stone tools from the site suggest a possible connection between these first Americans and Northeast Asian hunter-gatherers from the same period. Route closed due to iceA piece of charcoal unearthed in the lowest layer of sediment that contains artifacts is between 15,945 and 15,335 years old, according to radiocarbon dating. More charcoal, from the remains of an ancient hearth pit, dated to between 14,075 and 15,195 years old. A few other pieces of bone and charcoal returned radiocarbon dates in the 14,000- to 15,500-year-old range. In higher, more recent layers, archaeologists found bone and charcoal as recent as 8,000 years old, with a range of dates in between. This makes clear that people had been using the Cooper's Ferry site for a very long time, but it's hard to say whether they stuck around or just kept coming back. "Because we did not excavate the entire site, it is difficult to know if people occupied the site continuously starting at 16,000 years ago," Oregon State University archaeologist Loren Davis told Ars. "I expect that this site was used on a seasonal basis, perhaps as a base camp for hunting, gathering, and fishing activities." Either way, the local Nimiipuu (Nez Perce) people know the site as the location of an ancient village called Nipéhe. "We worked with archaeologists and student interns from the Nez Perce Tribe who visited to get tours of the excavation and to participate in excavations at the site," said Davis.  Davis and his colleagues used a statistical model to calculate how old the very oldest layers of artifacts at the site should be. "The Bayesian model makes predictions about the age of the lower portion of [the excavated layers] based on the chronological trend of known radiocarbon ages in the upper and middle third," Davis explained. According to the model, the very oldest artifacts at Nipéhe are probably between 16,560 and 15,280 years old. That's about 2,000 to 1,500 years before the great continent-spanning ice sheets of the Pleistocene began to break up. That break-up opened an ice-free corridor southward from the Bering land bridge between the towering sides of the Cordilleran and Laurentian ice sheets. According to computer simulations, that corridor was closed and buried under several kilometers of ice until at least 14,800 years ago, and possibly even later. And that has some important implications for when, and how, people first set foot in the Americas. The coastal routeIf the ice-free corridor wasn't open, the only way to get south of the ice sheets would have been to skirt along the Pacific coast on foot or by boat, moving among locations where the edges of the 4km (2.5 miles) thick glaciers didn't quite reach the Pacific Ocean. Much of Ice Age coastline is now underwater, largely thanks to the melting of those huge glaciers. But there have been a few recent archaeological finds that support the idea that the first humans in the Americans moved south along the coast much earlier than previously thought. Genetic evidence, which uses predictable rates of genetic mutations to tell how long ago populations separated from each other, suggests that sometime between 17,500 and 14,600 years ago, the people living south of the ice sheets split up into two major groups, which moved generally northward and generally southward. That lines up well with the timing at Nipéhe.  At this point, there's not really much debate about whether people had arrived in the Americas before the rise of the Clovis culture, the collection of tools and weapons once thought to represent the oldest human activity in the Americas. Clovis appears starting around 13,250 years ago, so some groups were clearly present earlier. Most of the debate now is focused on the route these earlier people took to reach the thawed, habitable parts of North America. Davis and his colleagues say Nipéhe is strong evidence for the coastal route. "This does not preclude subsequent human migrations through the [ice-free corridor] at a later time, as suggested by paleogenomics," they wrote, "but such possible population movements do not represent the initial peopling of the Americas." A Japanese connection?Buried in the Ice Age layers at Nipéhe, Davis and his colleagues found animal bones and discarded stone tools, including bifaces (two-sided handaxes; think of them as prehistoric multi-tools), blades, sharp stone flakes, and fragments of two projectile points. The tool collection didn't look a thing like the fluted projectile points that have become the archaeological calling card of the Clovis culture. To make a Clovis-style projectile point, the flint-knapper has to chip off a flake from one or both faces at a point right at the base of the object. That creates a small groove (also called a flute), which makes it easier to fit the point onto the shaft of a spear or arrow. But at Nipéhe (and at a few other pre-Clovis sites in the Americas), people took the opposite approach: they shaped the base of the point into a stem to attach to the spear or arrow shaft. Some of the younger stone tools from Nipéhe are about the same age as the Clovis culture, but they're clearly a separate technology. Stemmed projectile points aren't a recent technology, even by archaeological standards; people figured out that stems made points easier to haft by around 50,000 years ago in Africa, Asia, and the Levant. But there are different ways to shape a chunk of flint into a stemmed point, and the ones at Nipéhe look strikingly similar to stemmed points from Northeast Asia. Similarities are especially strong with items from the Japanese island of Hokkaido, which have turned up at sites dating between 16,000 and 13,000 years ago. (As an interesting side note, stemmed projectile points from a 13,500-year-old site in Kamchatka, in east Russia, were made with a distinctly different style.) Other aspects of the stone tools at Nipéhe also resemble the ones being made and used on Hokkaido at around the same time and slightly earlier. Davis and his colleagues claim that similarity is no coincidence. They suggest that the similar stone tool technology is evidence of a cultural link between the earliest Americans—who arrived on the Pacific coast and migrated southward before moving inland south of the ice sheets—and people in Northeastern Asia. The dates line up well; many of the Hokkaido sites with stemmed points are older than Nipéhe, while others are around the same age. That suggests that it's possible for the culture to have originated in Japan and then spread to North America—although it's impossible to guess how many generations removed the people of Nipéhe may have been from their relatives in Hokkaido by the time they dug their hearth pit in Western Idaho. Davis told Ars that archaeologists need to consider the possibility that two distant cultures happened to come up with the same stone-tool-making techniques at around the same time. But that seems unlikely. "These archaeological patterns require further study," he and his colleagues acknowledged in their paper. |  Artificial Intelligence / Machine Learning weekly classes (ONLINE)  Quality Tutoring  ALL-IN-ONE ONLINE REGISTRATION SOFTWARE        Principal,  Tel: (301)906-6889; (240)912-6290 Licensed in MD, VA, DC, WV, PA, DE, NC, SC, FL WeChat ID: sunnychenyuqing NMLS # 1220187 President, Principal Loan Consultant, Leader Funding, Inc.  电话: (240) 784-6645 Rockville, MD Phone: 301-366-3497  |
