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Life is a fragile condition, except when it isn’t. Hardly a week goes by without biologists discovering new feats of survival among living organisms – fungi that live underground for hundreds of years, algae that thrive in steaming-hot pools of toxic volcanic chemicals, and bacterial spores that just need the right conditions to become viable after millions of years in dormancy.
The latest survival story involves nematodes – that phylum of roundworms including more than 25,000 known species (and probably at least that many unknown). Most nematodes are harmless or even beneficial to humans, but many others parasitize livestock and cause significant damage to crops.
We know that various types of nematodes can be extremely resilient, such as with cattle worms that survive on pastures through freezing winters or extended drought, to emerge and parasitize animals once conditions become favorable.
Evidence from Siberia now suggests those little worms might be tougher than we ever guessed. A group of Russian scientists, working in collaboration with Princeton University, were analyzing soil samples from deep in the arctic permafrost, and found frozen nematodes. One of the samples came from soil deposits dated at 32,000 years old, and the other from 41,700 years ago. One sample was from 100 feet deep and the other from 15 feet – both in permafrost that’s been frozen for millennia.
The scientists placed some of the nematodes in petri dishes with a nutrient substrate and warmed to 68 degrees Fahrenheit. Lo and behold, some of the nematodes apparently emerged from a dormant state and began moving and feeding. Previously, scientists had revived nematodes after 39 years of dormancy. As mentioned earlier, some single-celled organisms such as bacteria, yeast and algae have survived for much longer time spans.
Discovery of these freeze-tolerant nematodes could have several scientific implications. On one hand, understanding the physiology that protects those nematodes from cellular damage during extended freezing might help development of freeze-tolerant crops, or long-term preservation of living tissue for medical purposes. On the other hand, the findings suggest that as the Arctic region warms, glaciers retreat and permafrost thaws, we could witness emergence of microbes, and even multicellular organisms such as nematodes, never before seen by humans. Potential consequences of that possibility remain unknown.
Read more from Smithsonian magazine.