A 2013 study in Nature reported that DNA found in the 24,000-year-old remains of a young boy from the archaeological Mal'ta-Buret' culture suggest that up to one-third of the indigenous Americans may have ancestry that can be traced back to western Eurasians, who may have "had a more north-easterly distribution 24,000 years ago than commonly thought". "We estimate that 14 to 38 percent of Native American ancestry may originate through gene flow from this ancient population," the authors wrote. Professor Kelly Graf said,

Answer this question, if possible (if impossible, reply "unanswerable"): What may one-third of the indigenous Americans ancestry be traced back to?
western Eurasians