language families

A language family is a group of languages related by descent from a common ancestor, called the proto-language. As with biological families, the evidence of relationship is observable shared characteristics. An accurately identified family is a phylogenetic unit; that is, all its members derive from a common ancestor, and all attested descendants of that ancestor are included in the family. Most of the world's languages are known to belong to families; for many others, however, family relationships are not known or only tentatively proposed.
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