Apparently there are a few words in Asia that have survive millenniums. http://www.washingtonpost.com/national/health-science/linguists-identify-15000-year-old-ultraconserved-words/2013/05/06/a02e3a14-b427-11e2-9a98-4be1688d7d84_story.html
The article offers no evidence. Some linguists took some 2000-year-old words which have changed little, assumed they have changed little for 15,000 years, and assumed they know how they were pronounced. Publish or perish. They'll get raises for this from their colleges.