Horse’s genetic evolution mapped

Tuesday 02 Jul 13


Josef Korbinian Vogt
DTU Bioinformatics
+45 31 48 63 13
DTU researchers have succeeded in mapping the genes of a horse that lived 700,000 years ago. This is several hundred thousand years older than the previously oldest known whole genome. The results were recently published in the magazine Nature, and these new data will help improve our understanding of the evolutionary process and development of the horse as a species.

Buried in permafrost in a remote Canadian valley, scientists discovered a small piece of fossil bone in 2003. The bone proved to be from the hind leg of a horse, enabling scientists to establish that it was between 560,000 and 780,000 years old. Using state-of-the-art methods for extracting and sequencing even the tiniest amounts of DNA, researchers from the Centre for GeoGenetics, University of Copenhagen, succeeded in isolating sufficient usable DNA for an in-depth analysis. Last year, the 12 billion tiny digital DNA fragments were handed over to DTU Systems Biology researchers, who have now solved the huge jigsaw puzzle: the precise order of the base pairs that make up the prehistoric horse’s complete genome. .

Only 1% horse

"With the new genomes, we can begin researching into which specific genes make the Arabian Horse a racehorse or the Icelandic Horse such a strong workhorse for example"
Thomas Sicheritz-Pontén

In order to map an entire genome for an unknown prehistoric horse, DTU researchers compared every tiny fragment of DNA with all known animal, bacteria and virus genes, as only about 1% of the bone DNA actually belonged to the horse. The rest belonged to other organisms, primarily bacteria, and when there are billions of DNA sequences to map, it is a huge and lengthy task requiring tremendous computer power and extensive know-how, explains Thomas Sicheritz-Pontén from Centre for Biological Sequence Analysis, DTU Systems Biology. The Centre possesses the super computers and expertise to produce the valuable data sets that comprise whole genomes.

Exciting work ahead

DTU researchers Thomas Sicheritz-Pontén, Bent Petersen and Josef Vogt have worked on the horse genome for almost a year. However, the project—a major international collaboration involving numerous partners— encompasses far more than the the 700,000 year old horse.

“We have also mapped and analyzed the genome from the only wild horse in existence, Przewalski’s from the Mongolian Steppes, and that of a donkey as well as five different modern horse breeds, including the Arabian Horse, the Icelandic Horse and the Norwegian Fjord Horse,” says Bent Petersen

With the new results recently published in Nature magazine, a major important branch can now be added to the evolutionary tree—namely everything pertaining to the horse species. All genomes form part of the accessible NCBI database, paving the way for numerous new and exciting research projects relating to the origin and development of the horse—and not least the genetic role played by man, who has domesticated the horse and bred different specific characteristics.

"And now we start the truly exciting work. With the new genomes, we can begin researching which specific genes make the Arabian horse a racehorse or the Icelandic horse such a strong workhorse, for example,” says Thomas Sicheritz-Pontén.