Like a family tree that you might use to trace back through generations of ancestors, only it's showing a family of genetically relatedlanguages instead of people.
就像你可以追溯祖先的家谱一样，它只是在显示与遗传相关的语言，而不是人类。
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Perhaps the most striking sign of mobility is the fact that by the third millennium B.C., most pastoralists in this huge region spoke relatedlanguages ancestral to the modern Indo-European languages.