A new DNA experiment leads to the oldest genome sequence in history.
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An international team of scientists has sequenced the genome of a 735,000 year old horse, making it the oldest genome ever deciphered. The achievement is providing new answers to questions about the evolution of the Equus genus, which includes all modern horses, donkeys, and zebras. The oldest previous DNA sequences came from a polar bear that lived between 110,000 and 130,000 years ago. The team’s findings are detailed in the June 26 issue of the journal Nature.
The researchers extracted DNA from a fossilized leg bone of an ancient horse that once roamed what is now Canada’s Yukon Territory. After pulverizing a bone fragment and subjecting it to high throughput, next-generation gene sequencing, the scientists were able to tease out 70 percent of the animal’s complete genome. That was enough to reveal some important secrets about both the individual creature and the evolutionary history of the horse. Because the bone was kept in virtual cold storage by being buried in permafrost, the remains of its ancient DNA were better preserved than in most fossil specimens, according to researchers.