Say No More

"Jack Hitt article on how languages die and efforts to keep them alive; notes estimate that half of more than 6,000 languages currently spoken in world will become extinct by end of century; says working to stem tide range are graduate students heading into the field to compile dictionaries, charitable foundations devoted to the cause, like Endangered Language Fund, and transnational agencies, like European Bureau for Lesser Used Languages; describes scene in Puerto Eden, tiny fishing village on Wellington Island in Patagonia region of southern Chile, home of last six speakers of Kawesqar, language native to area since last ice age; photos (L)"