标题: [求助]争议题啊？ [打印本页] 作者: manliangiggs 时间: 2008-10-21 21:16 标题: [求助]争议题啊？ Scientists have dated sharp-edged flakes of stone found in the fine-grained sediments of a dry riverbed in the Afar region of Ethiopia to between 2.52 and 2.60 million years ago, pushing back by more than 150,000 years the earliest date when it is known that humans made stone tools.