Supernature: Notes on the Worms of Chernobyl

Nematodes collected from the CEZ

(as seen under a microscope)
Image: Sophia Tintori / NYU 

 

 

I.

 

First it was the mutant wolves [1], then the black-skinned tree frogs [2], now it's the nematode worms living in the Chernobyl Exclusion Zone (CEZ) that are making the headlines; apparently they have developed a new superpower - immunity to radiation [3]. 

 

I have to admit, that's a bit disappointing. For when I first heard of this story I couldn't help imagining that the tiny creatures were now able to move faster than a speeding bullet, or leap tall buildings in a single bound. 

 

Alas, that's not the case, and one rather wishes that scientists (and/or journalists who report on scientific research) would moderate their language. Still, it's an exciting discovery nevertheless and only makes these resilient worms even more astonishing than they already were.

 

 

II.   

 

Commonly known as roundworms or eelworms, nematodes are an extraordinarily diverse group of genetically non-complex animals that have been inhabiting a wide range of environments for at least 400 million years (and perhaps more than twice that long).

 

In fact, nematodes have successfully adapted to almost every ecosystem; from the polar regions to the tropics. Wherever you look - from mountain tops to deep beneath the surface of the sea - you'll find these tiny worms living and reproducing quite happily.   

 

Most species are free-living and feed on micro-organisms, but many are parasitic and some of these can cause disease in plants and animals (including human beings).

 

It's uncertain how many species of nematode there are; guesstimates range from the tens of thousands to over a million and there are so many of them that they account for around 80% of all individual animals on Earth. And we think the planet belongs to us ...

 

When taken into space aboard the Space Shuttle Columbia in 2003, a group of nematodes did just fine, even surviving a virtually unprotected re-entry into the Earth's atmosphere. In the same year, an individual roundworm was revived after surviving for approximately 46,000 years in Siberian permafrost [4].    

 

In sum: nematodes even outside the CEZ might be said to possess superpowers and it makes me happy to know that, long after we are no more, they will still be. 

 

Notes

 

[1] See 'Cara Love and the Mutant Wolves of Chernobyl' (14 Feb 2024): click here. 

 

[2] See 'Reflections on the Black Tree Frogs of Chernobyl' (22 Feb 2024): click here.

 

[3] Readers who wish to know more about the research carried out by Sophia Tintori and her colleagues from NYU should click here.

 

[4] In a research project published in 2012, it was found that Antarctic nematodes were able to withstand intracellular freezing providing they were well nourished.

 

Reflections on the Black Tree Frogs of Chernobyl

A tree frog shown before and after the 

Chernobyl nuclear accident in 1986

 

 

I. 

 

I have always liked D. H. Lawrence's description of little green frogs as gem-like [1].

 

But it seems that the frogs living in the Chernobyl Exclusion Zone (CEZ) are no longer emerald green in colour. For in order to increase their survival rates in an irradiated environment, the frogs have undergone rapid evolution and now model jet black skins rich in protective melanin [2].

 

In 2016, whilst researching the effects over the previous three decades of Chernobyl's uniquely polluted environment on the flora and fauna, two Spanish scientists [3] made a strange discovery ... 

 

They expected to find that plant and animal species subjected to daily doses of radiation way above normal levels would have experienced negative consequences, but what they did not anticipate was that nature would respond in such an amazing way and recover so quickly - and they certainly weren't on the lookout for black frogs!

 

 

II.

 

So, what on earth is going on here? 

 

Well, cancer resistant wolves [4] and ebony-skinned tree frogs would seem to suggest that the Chernobyl disaster, which generated the largest release of radioactive material into the environment in human history, has accelerated natural evolution in a manner that Darwin - who always liked to stress the slow and gradual nature of evolutionary change by natural selection [5] - would have found hard to believe.   

 

And this - along with the absence of human beings - helps to explain why Chernobyl has become one of the largest nature reserves in Europe, where a diverse range of endangered species find refuge and live happily (or at least successfully) side-by-side. 

For whilst acute exposure to high doses of radiation can cerainly be damaging, both to the natural environment and the genetic material of living organisms, it can also kick-start and accelerate evolution in a surprisingly positive way, as species adapt to the new conditions. 

 

 

Notes

 

[1] See D. H. Lawrence, 'The State of Funk', in Late Essays and Articles, ed. James T. Boulton, (Cambridge University Press, 2004), p. 221. 

 

[2] The pigment melanin which, as many people know, reduces the effects of ultraviolet radiation, can also, so it seems, afford protection against ionising radiation. And that's why it's better to be a black frog than a green frog if you're going to spend your life hopping about in the CEZ.   

 

[3] Germán Orizaola and Pablo Burraco; they discuss their study of over 200 male tree frogs taken from twelve different breeding ponds from various sites in northern Ukraine - including four outside the CEZ - in an article originally published on theconversation.com (28 Sept 2022): click here.  

      As Orizaola y Burraco make clear, the dark skin colouration is typical of frogs from within or near the most contaminated areas at the time of the Chernobyl disaster and it suggests that they have undergone a process of rapid evolution in response to the radiation. The black frogs, having better survival rates, are now the dominant type within the CEZ, which, in my view, is a bit of a shame, as I prefer the little frogs with bright green skins. 

 

[4] See the recent post entitled 'Cara Love and the Mutant Wolves of Chernobyl' (14 Feb 2024): click here.

 

[5] In what is considered to be the founding text of evolutionary biology - On the Origin of Species (1859) - Darwin emphasises how natural selection progresses at a glacial pace and we usually observe nothing of the changes being made until long periods of time have passed. 

      Although this is true, adaptation to new conditions can occur within a relatively short period of time and examination of the fossil record shows that many species undergo rapid bursts of evolution, even if true speciation takes time. Recent work in developmental biology has identified certain mechanisms of tissue morphogenesis that may help explain any swift structural transitions. 

      I am grateful to Dr Andy Greenfield - my go to science guy and longtime friend - for his guidance on this point.

 

 

For a frog-related follow-up post to this one, click here.

 

 

Cara Love and the Mutant Wolves of Chernobyl

Dr Cara Love and a grey wolf 

Images via caranlove.com 

 

 

I. 

 

Since it's Valentine's Day, I thought it might be appropriate to give a shout out to Love - Cara Love, that is, a post-doctoral research fellow at Princeton University who specialises in the ecological and evolutionary consequences of anthropogenic stressors in a variety of species worldwide, but who has recently been in the news due to her work with the grey wolves of the Chernobyl Exclusion Zone (CEZ) ... 

 

II.

 

As many readers will know, ever since the nuclear reactor at the Chernobyl power plant exploded back in the spring of 1986, a 1000 square-mile exclusion zone has been maintained in order prevent the evacuated residents from returning to an area where radiation levels remain dangerously high.   

 

This hasn't, however, stopped many forms of wildlife - including wolves, horses, bears, bison, and wild boar - from occupying the zone and multiplying in a contaminated but, crucially, human-free environment.   

 

Whilst there are several scientific studies involving the wolves who live at the heart of the exclusion zone, and most of these are being conducted in the hope that they may enable researchers to better assess the impact of radiation levels on the health of the animals, it seems to be Dr Love who is being credited with the amazing discovery that Chernobyl's wolves - after generations of exposure to radioactive particles - seem to have developed resistance to cancer.    

 

Love and a team of researchers visited the CEZ in 2014 and have been monitoring a number of wolves fitted with radio collars since then. They discovered that the animals were exposed on a daily basis to a level of radiation more than six times the legal safety limit for people. 

 

Dr Love also found that the wolves have altered immune systems similar to cancer patients undergoing radiation treatment, but, more significantly, she identified specific parts of the wolves' genome that seemed resilient to increased cancer risk. In other words, the wolves have genetically mutated in a manner that is beneficial to their survival.

 

Unfortunately, recent events - the Covid pandemic and Russia's invasion of Ukraine - have prevented Dr Love and her colleagues from returning to the CEZ in recent years. Nevertheless, she felt able to present her findings so far to a meeting of the Society of Integrative and Comparative Biology in Seattle, Washington, last month.

 

The hope is that Love's work with mutant grey wolves will one day help to prevent (or treat) cancer in human beings. But my concern, however, is that this will inevitably lead to cruel experimentation on the wolves (and doubtless other mammals) currently inhabiting a radioactive paradise ...