Science & Technology

Those 40,000-Year-Old Worms Aren't Even the Oldest Organisms to Come Back to Life

Worms are surreally hardy creatures. Russian researchers recently found microscopic, intact worms in permafrost from 40,000 years ago — and when they thawed the ice, the worms came back to life. But if you think that's ancient, just wait until you hear about the other organisms that have come back to life.

The Worms That Lived

The two worms in question aren't exactly earthworms. They're nematodes — tiny translucent worms, a few hundred microns long, that you can only see under a microscope. Russian researchers discovered the ancient, intact nematodes in samples of the permafrost in Siberia. Of their 300 permafrost samples from the Kolyma River lowland, the nematodes cropped up in two that dated back to the late Pleistocene period. That's 30 to 40 thousand years ago. For context, that was the era of the most recent ice age, around when humans first spread across the Earth. Hopefully, they had jackets.

At first, the researchers only knew the nematodes were intact. But then they thawed the permafrost samples and surrounded each in nematode food. Over the course of a few weeks, the worms began to wriggle and eat the food. Though they had been frozen, it turned out they had never quite died. Instead, not unlike Austin Powers, they had remained in suspended animation for millennia, poised to reanimate when their surroundings thawed.

What Can Ice Do?

The worms' surprise victory over ice and the passage of time is scientifically important — but not because we didn't know long-frozen lifeforms could reanimate. It's well-established that single-celled organisms, frozen in ice or preserved in amber for hundreds of thousands, even millions of years, can reanimate.

Compared to those bacteria, the newly-discovered nematodes are downright youthful, but this case is still groundbreaking: It's the first time multicellular organisms, more complex than bacteria, revived after millennia on ice. Previously, another organism — the tardigrade — had survived freezing, but only for a short time. The tiny, surprisingly pig-like creatures that can survive basically anything: outer space, freezing cold, extreme heat, and intense radiation. Japanese researchers had brought two tardigrades back to life after they had been frozen for 30 years — but thirty years is small change compared to what the worms endured.

Well, probably endured. As with all things in science, nothing is completely certain after one paper. The researchers went to great lengths to keep their permafrost samples sterile, but it's possible — though not probable — that the samples were somehow polluted with modern worms. So this research should be taken with a grain of salt.

Still, if it's corroborated by further studies, that means ice is a very powerful preservative. Freezing temperatures can, in a way, freeze time for many creatures. This is delightful in that it opens up the possibility of humans freezing themselves. At the same time, ice's freakish powers could put us in danger. Though there's no evidence that the nematodes in question here could be harmful to humans, ice is melting worldwide, reanimating ancient bacteria that's not all friendly. Some have compared the melting of permafrost to opening "a Pandora's box of diseases."

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Fascinated by what life was like millions of years ago? Check out "The Rise and Fall of the Dinosaurs: A New History of a Lost World" by Steve Brusatte. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Mae Rice July 30, 2018

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