VOA慢速英语视频:Study Says Bubonic Plague Much Older Than Thought
2015-11-18来源:和谐英语
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Danish researchers examining ancient human teeth have discovered evidence of the plague from 4,800 years ago. In the middle 1300s, the disease killed 50 to 60 percent of Europe’s population. But the bacterium was not nearly as aggressive in its earlier form says the study leader.