In this undated photo provided by Ludovic Orlando via Nature, two pieces of a 700,000-year-old horse metapodial bone, just before being extracted for ancient DNA, are shown. From a tiny

 

              In this undated photo provided by Ludovic Orlando via Nature, two pieces of a 700,000-year-old horse metapodial bone, just before being extracted for ancient DNA, are shown. From a tiny
In this undated photo provided by Ludovic Orlando via Nature, two pieces of a 700,000-year-old horse metapodial bone, just before being extracted for ancient DNA, are shown. From a tiny fossil bone found in the frozen Yukon, scientists have deciphered the genetic code of an ancient horse about 700,000 years old _ nearly 10 times older than any other animal that has had its genome mapped. The work was published Wednesday, June 26, 2013, by the journal Nature and discussed at a science conference in Helsinki. (AP Photo/Ludovic Orlando via Nature)