700,000-Year-Old Horse Genome Is Oldest Ever Sequenced by a Factor of 10 | Smart News | Smithsonian
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700,000-Year-Old Horse Genome Is Oldest Ever Sequenced by a Factor of 10

The study authors say that the horse genome hints that it may be possible to sequence the genomes of organisms that lived up to 1 million years ago

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Part of the 700,000-year-old bone fragment used to sequence the DNA. Photo: Ludovic Orlando

Researchers just announced that they’ve completed work on the oldest genome ever sequenced—from a 700,000 year-old horse that once roamed Canada’s Yukon Territory, Bloomberg reports. And by comparing the ancient horse’s genetic material with that of other ancient and modern horses, the researchers were able to calculate that that the common ancestor for modern day horses, zebras and donkeys lived from 4 to 4.5 million years ago—about twice as long ago as scientists had thought. Bloomberg:

The finding is remarkable because DNA, the hereditary material in almost all organisms, generally starts to fragment after an organism’s death, the researchers said. The group made its discovery by matching the genetic material of the horse found in Canada against DNA sequenced from a horse that lived 43,000 years ago; a Przewalski horse, thought to be the last wild horse; five modern domesticated breeds; and a donkey. The finding also means that DNA pieces retrieved from old samples may also have information about how the current world evolved, the study authors wrote.

The ancient horse DNA is around 10 times older than what previously were the oldest genetic samples. The cold environment, the researchers told Bloomberg, likely helped preserve the sample.

The study authors say that the horse genome hints that it may be possible to sequence the genomes of organisms that lived up to 1 million years ago. The Scientist elaborates:

That opens up the possibility of getting genomic information from ancestral human specimens like Homo heidelbergensis and Homo erectus.

“Such genomic information, in combination with the Denisovan and Neanderthal genomes, would undoubtedly shed light on the evolu­tion of humans and our hominin ancestors,” wrote Lambert and Miller.

Sequencing those ancestral human genomes would also raise all sorts of questions about bringing our ancient relatives back from the oblivion. De-extinction techniques are currently being discussed or species such as the passenger pigeon and wooly mammoth—but resurrecting Homo erectus would be a whole new conversation.

More from Smithsonian.com:

Resurrecting Extinct Species Is Conservation’s Next Frontier 
Scientists Use 100-Year-Old DNA to Validate Species 

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