UCSC Scientists Study 700,000-Year-Old Horse; Oldest DNA Sequenced

UCSC scientists were part of a team that recovered and studied the oldest genomes found on earth, those of a 700,000-year-old horse.

The horse's bone was found frozen in the world's oldest permafrost in Canada's Yukon Territory, according to a release from UCSC. The team's research was published today in Nature.

UCSC researcher Beth Shapiro, associate professor of ecology and evolutionary biology led a team that characterized the site where the bone was found and sequenced and assembled the horse's genome.

"This is exciting in that it pushes back the time in which DNA is recoverable by nearly an order of magnitude," Shapiro said. "The bone was recovered from the oldest known permafrost, so it is a special case. Had it not been frozen for the entire duration of that 700,000 years, I doubt that any recoverable DNA would have survived. As a consequence, it's a real treasure!"

The researchers, led by Ludovic Orlando, of the Center for GeoGenetics at the Natural History Museum of Denmark, compared the horse's genes to those of one from 43,000 years ago and six modern horses and a donkey, and found that the ancestors of horses lived about 4-4.5 million years ago, twice as long as previously thought. 

Their research focuses on how wild horses differ from domesticated ones and what changes occurred between domesticated and wild horses over time.

"In order to really tease out the evolutionary changes associated with horse domestication, we need to know where the genes are in the genome and what they do, which means we need a better annotated genome of the modern horse," Shapiro said. "But using these older genomes is a great start--it can point us to regions of the genome that appear to have been evolving under selection for tens or even hundreds of thousands of years. Now we just have to figure out why."