[ti:Scientists: First People in Americas Arrived at Least 16,600 Years Ago] [by:www.51voa.com] [00:00.00]更多听力请访问51VOA.COM [00:00.01]Stone tools and pieces of animal bone from about 16,600 years ago [00:08.73]are the earliest evidence yet of human beings in the New World, scientists say. [00:16.97]The objects were found in the western United States. [00:23.10]They were recovered from an archeological site called Cooper's Ferry [00:29.44]on the Salmon River near the town of Cottonwood, Idaho. [00:35.50]Scientists used radiocarbon dating methods to find out how old these artifacts are. [00:46.53]The scientists say people lived in or passed through the area [00:53.10]at a time when ice covered large parts of North America. [00:59.60]That period of time is known as Earth's Ice Age. [01:06.33]During the period, big mammals like mastodons, saber-toothed cats and camels lived in North America. [01:19.48]Loren Davis is an anthropology professor at Oregon State University. [01:27.86]He led the team of scientists working at Cooper's Ferry. [01:33.94]A report on the study and their findings was published in Science magazine. [01:42.02]"The Cooper's Ferry site is the earliest radiocarbon-dated archaeological evidence in the America's," Davis said. [01:54.49]The researchers said the artifacts suggest that people first lived in the area [02:02.94]between 16,600 and 15,300 years ago and returned to live there many times after that. [02:16.37]The oldest objects include four sharp stone tools, which were used for cutting and scraping. [02:26.86]The scientists also found pieces of stone left from making the tools. [02:34.71]They also found burnt pieces of wood, rock that had been split by heat from fires [02:43.51]as well as particles of animal bone particles and pieces of horses' teeth. [02:50.99]Horses were once native to North America but later disappeared. [02:58.32]Scientists say humans first appeared in Africa about 300,000 years ago and later spread throughout the world. [03:11.95]There has been much scientific debate about when humans first entered the Americas. [03:20.08]They are believed to have crossed into North America at a time when Siberia and Alaska were connected by land. [03:31.78]The new findings support the hypothesis that the first human migration into the Americas [03:40.82]traveled down the Pacific coast instead of an inland path. [03:47.99]Davis said, "The Columbia River would provide the first Americans their first route [03:56.19]to interior lands south of the continental ice sheets." [04:02.76]The Columbia is the biggest river flowing into the Pacific Ocean from North America. [04:11.19]It might have provided a way for the early migrants to travel into the North American land mass. [04:21.43]The researchers noted details of some of the sharp objects that would have been used for hunting. [04:31.16]These artifacts appear similar to those found in northern Japan from a somewhat earlier date. [04:41.28]Davis said, "We hypothesize that this may signal a cultural connection [04:49.39]between early peoples who lived around the northern Pacific Rim." [04:56.03]"Traditional technological ideas spread from northeastern Asia into North America [05:05.22]at the end of the last glacial period," he added. [05:11.00]I'm Mario Ritter, Jr. 更多听力请访问51VOA.COM