Linguists identify 15,000-year-old ‘ultraconserved words’ https://www.washingtonpost.com/national/health-science/linguists-identify-15000-year-old-ultraconserved-words/2013/05/06/a02e3a14-b427-11e2-9a98-4be1688d7d84_story.html?utm_term=.03bd277a7abe