Frozen DNA reveals ancient animals

Permafrost dating from 30,000 years old, Klondike area, Yukon. These sediments include well-preserved DNA from ancient plants and mammals, including bison, horse and mammoth. (PHOTO BY D.G. FROESE)

ED STRUZIK
Postmedia News

University of Alberta scientist Duane Froese was on sabbatical last summer when he received a call from a Yukon miner who wanted to give him the headsup about a site he planned to excavate.

Like most Klondike miners, Tony Beets is a character. He’s tall, bushy-haired, drives fast and uses colourful language.

But he’d also been incredibly helpful over the years, moving in heavy equipment for scientists such as Froese, exposing layers of ancient permafrost that yielded the frozen bones of woolly mammoths, scimitar cats, shortfaced bears and other animals that lived in this part of the world before the last major Ice Age ended 11,500 years ago.

Shortly before Froese arrived on the scene, his team already had unearthed some woolly mammoth bones that Beets had exposed.

The fossil that stood out the most, however, was the skull of a horse that had lived in the Arctic during the last Ice Age.

This was not the typical small Yukon horse that Froese and other paleontologists had found here and in other regions of the Arctic. This was a huge animal – a Clydesdale next to an Icelandic pony.

“The fossils of horses like these show up rarely in North America,” says Froese, who considers himself to be a geologist rather than a paleontologist.

No one knows exactly why half of these Ice Age animals disappeared from the landscape so quickly. Working with geneticist Eske Willerslev, Yukon paleontologist Grant Zazula and other scientists from Australia, Scotland, England, and the United States, Froese found evidence at a site along the Yukon River in Alaska a few years ago that puts a new, radical spin on the debate.

The evidence they found near Stevens Village showed that some Ice Age animals such as the woolly mammoth and the giant horse lived several thousand years longer than previously thought in so-called “ghost ranges” of the western Arctic.

What is surprising is how Froese and his colleagues came to this conclusion. The evidence they unearthed from that site along the Yukon River in Alaska didn’t come from fossils; it came from the DNA extracted from the hair, skin, feces, urine or possibly skin cells the animals left behind.