World’s oldest DNA discovered in Greenland, studied by Halifax geoscientist

A significant DNA discovery in Greenland has been revealed this week – and its research has a Maritime connection.

A study published in the Nature journal Wednesday said the world’s oldest DNA has been found in sediment samples from the high arctic dating back 2-million years.

John Gosse, a professor of earth and environmental sciences at Dalhousie University in Halifax, was sought out to date the material.

He says the study shows the technical advancement in extracting DNA from “something really old.”

“Up until this science, this nature paper, what we’ve learned is that DNA needs to be kept cold because it will break apart. Over time, these ladders of that molecule, very long chains, will break apart into many pieces,” he told CTV’s Todd Battis during an interview.

“Biologists figured out, a long time ago, that we need to find pieces of material to sequence in frozen ground – and that allows it to, the breakdown of those molecules, to slow down. And so you have a better chance.”

The oldest DNA sequence known previously was taken from a mammoth tusk in Siberian permafrost dating from 1.1 million years ago.

The group of scientists who made the recent discovery travelled to northern Greenland from Copenhagen in the summers of 2006, 2012 and 2016 and sought out permafrost for DNA extraction.

They also took samples from quartz and clay found in the Kap København Formation.

Over time, the scientists discovered that the minerals had DNA absorbed in them.

“When we hold clay, it’s made up of millions of flat crystals. And the flat crystals, their faces have charges. They’re charged just like a balloon in your hair would be charged to stick on a wall. But the molecules of DNA are also charged and so if we could stick the DNA to the clay it will resist breakdown even more,” said Gosse.

Gosse refers to the clay discovery as the “big breakthrough” for the study.

“Maybe we don’t need just permafrost, but maybe we need the clay. And so not only can we date a 2-million-year-old sand and then measure the DNA in it, maybe we could do this in Africa, in clay, and start to look at human DNA.”

Present-day Greenland is often thought of much like any other Arctic island, but the newly found DNA is helping to paint a clearer picture of what the region looked like 2-million years ago.

“The Greenland ice sheet has shrunk and swelled,” says Gosse. “At the time that the 2-million year old DNA comes from, the Greenland ice sheet was pulled back, so it was an interglacial [period] like today, and it had trees unlike today, it had hares, there were poplar and birch there, but the big finding was mastodon.”

Gosse will go on an expedition to the arctic next summer along with DNA researchers from the University of Copenhagen for further research at a 4-million-year-old site.

“Where we really know the age pretty well and there’s been decades of research on the paleontology,” he says. “They’re gonna go to the clays that we know where they are and try to sample – hopefully we can get the samples back frozen.”