A careful examination of frozen caribou poop has turned up two never-before-seen viruses.
The viruses are hundreds of years old: One of them probably infected plants the caribous ate. The other may have infected insects that buzzed around the animals.
The findings prove viruses can survive for surprisingly long periods of time in a cold environment, according to Eric Delwart, a researcher at Blood Systems Research Institute in San Francisco.
"The DNA of viruses is preserved extremely well under cold conditions," he says.
Delwart's day job at Blood Systems is to find new viruses that could contaminate the blood supply. But he enjoys looking in odd places too. He got interested in ice cores from high mountain regions, after reading about all the interesting old things the ice contained.
"Things like old shoes and arrowheads," he says, "and then I realized this is nature's freezer, which should also contain organic remains."
Delwart had one particular type of organic remains in mind: caribou poop. Just about everything an animal eats can be infected with a virus. And that makes animals, including humans, virus vacuums that suck up every virus in their path.
"I mean we're constantly shoving viruses down our throat and if you look at poo samples from humans and from animals you will find a lot of viruses," he says.
Caribous hang out on ice, so these pristine ice cores are actually full of poo. And as scientists go through layer after layer of ice, the poo gets older and older.
Delwart examined poop from northern Canada that was 700 years old. The result, published Monday in the Proceedings of the National Academy of Sciences, is the discovery of these two viruses.
The DNA was so well-preserved that Delwart's collaborators could even reconstitute one virus and use it to infect a plant in the lab.
As far as Delwart can tell, these viruses aren't dangerous, which is good. As the North warms and ice melts, more caribou poo infected with ancient viruses will be finding its way into the modern ecosystem.
ROBERT SIEGEL, HOST:
When we think of viruses, we tend to think of the dangerous ones, like Ebola. But viruses are everywhere, and there are lots of different kinds. Today, researchers published the discovery of two more. As NPR's science correspondent Geoff Brumfiel explains, they were found frozen deep underneath the ice of northern Canada.
GEOFF BRUMFIEL, BYLINE: Dr. Eric Delwart works at Blood Systems Research Institute in San Francisco.
ERIC DELWART: My day job is to discover new viruses.
BRUMFIEL: New viruses that could contaminate the blood supply. The company he works for, Blood Systems, is a major blood provider to hundreds of hospitals. But Delwart's also got a sort of hobby of trying to find viruses in odd places, which is how he got interested in high mountain ice. All sorts of stuff is hiding down there.
DELWART: Things like old shoes and arrowheads - and then I realized this is nature's freezer, which should also contain organic remains.
BRUMFIEL: Organic remains is his little euphemism for...
DELWART: Tons of caribou poo.
BRUMFIEL: That's right - tons of caribou poo. Just about everything an animal eats - meats, vegetables - all of it can be infected with viruses.
DELWART: I mean, we're constantly shoving viruses down our throats. And if you look at poo samples from humans and from animals, you will find a lot of viruses.
BRUMFIEL: Mostly harmless ones. Caribou are no exception. They've lived in Northern Canada for millennia, and for just as long, as they've been doing their business on patches of mountain ice. Scientists drill out cylinders of the ice to study the past, and sometimes, stuck in that record is a little bit of poo.
DELWART: So we analyze four layers, starting at...
BRUMFIEL: Four - wait, wait, wait - four layers of ice or four layers of poo?
DELWART: Four layers of poop.
BRUMFIEL: And there, in a 700-year-old sample, they discovered two viruses that had never been seen before. They're described in the journal PNAS. One likely infected plants the caribou ate. The other may have infected insects buzzing around them. The viruses were still in amazing shape.
DELWART: The DNA of viruses is preserved extremely well under cold conditions.
BRUMFIEL: They even got the plant one to infect a modern plant. As far as Delwart can tell, it isn't dangerous, which is good because as the North warms, and ice melts, more ancient caribou droppings and the viruses they host will be thawing their way into the modern ecosystem. Geoff Brumfiel, NPR News. Transcript provided by NPR, Copyright NPR.