请问一句翻译 T-4-Q1TS-7-41Scientists 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 at which humans are known to have made stone tools.
push back by more than 150000 years 怎么翻译,the earliest date 是修饰谁啊,不应该修饰前面这个pushing....years?150000years只是一个变化量,可是the earliest date应该修饰的是一个具体时间吧。