The black frogs of Chernobyl
Adaptation at the site of the world’s worst nuclear disaster
Eastern Tree Frogs (Hyla orientalis) near the partially abandoned city of Chernobyl in northern Ukraine have changed colour in the last few decades. Is this change an example of ‘evolution in action’?
When the region was still part of the former Soviet Union, the nuclear reactor there underwent a catastrophic meltdown (26 April 1986).
It seems that in response to the high level of ionizing radiation released, the frogs have developed very dark skin (from formerly bright green to black/dark brown). The higher concentration of the pigment melanin in their skin helps to protect them from the radiation.1
This change is being used as an example of evolution observed in nature. But it is clearly nothing of the sort. Calling it ‘evolution’ is an example of the logical fallacy of equivocation, or ‘bait and switch’, which CMI has written about.2 Whether used as a conscious strategy or not, this involves using the same word to refer to different things, without clarifying the difference in meaning.
Equivocation on display
The real dispute about ‘evolution’ is about the ‘general theory of evolution’. That is, about a process which is claimed to have produced all life on Earth from one ancestral cell, which itself came from non-living chemicals.3
But the Chernobyl4 frogs do not support this grand claim. The change in frog colouration at Chernobyl is simply the result of adaptation, by means of natural selection (differential reproduction). Lighter-coloured frogs that become sickly or even die due to the radiation will not produce as many offspring as those darker ones that happen to already have more melanin in their skin. So the darker ones will come to outnumber the lighter-skinned ones, which may even die out altogether.
To elaborate, at Chernobyl we had a population of frogs that already contained variations in skin tone. Some had very light skin, some had much darker skin. When the radiation increased, pale-skinned frogs would be harmed more than darker frogs and would reproduce at lower rates, if at all.
As time went on the darker frogs would be more likely to only find darker, better-protected frogs to breed with. The darker the skin tone, the more protection, so this process would continue until genes for dark skin were so prevalent that the whole population was primarily very dark in skin tone. Notice, things started with a large degree of variation in skin tone, we now have much less variation in skin tone. Nothing new was added to the population; it already contained genes for producing melanin. And if anything, it lost some of the genetic variety (the genes for light skin).
Why it’s not evolution
Darker-skinned frogs outbreeding lighter-skinned frogs is not an example of the type of change needed to justify the big picture story of evolution. Humans supposedly evolved from fish, yet humans contain numerous structures and genes that fish do not have. For such a transformation to occur, new structures, processes, and functions would need to arise, along with whole new gene families.5 However, these frogs show no evidence of such novelty.
Could mutations be involved?
Mutations (mistakes in copying DNA) are said to be the genetic fuel that natural selection uses to drive evolution forward, by providing the opportunity for genetic novelty.
Radiation in the environment does make mutation more likely. But it is not feasible that such a random change could generate ‘from scratch’ the biological machinery needed to make melanin. Frogs in general already produce melanin, which in green frogs is normally found in the bottom pigment layer of their complex skin structure.
Mutation can sometimes lead to overproduction of a substance already being manufactured, through damage to control mechanisms.1 While something like that is possible here, no such claims are being made. Rather, the genes for darker skin favoured by natural selection probably already existed in the population.
- E.g., mutation-caused penicillin resistance; see Batten., D., Antibiotic resistance: Evolution in action? Creation 39(4):46–48, 2017; creation.com/antibiotic.
Summary and conclusion
Losing genes for lighter skin from the population is indeed an example of natural selection, but the kind of change that occurred here is clearly not evolution as generally understood.6 To call this ‘evolution’ is therefore misleading at best, and deceptive at worst. Even if it were to be extrapolated for eons of time, such a ‘downhill’ process has no way of changing amphibians into astronomers.
References and notes
- Orizaola, G., et al. Chernobyl black frogs reveal evolution in action, phys.org, 29 Sep 2022. Return to text.
- Walker, T., Don’t fall for the bait and switch, Creation 29(4):38–39, 2007; creation.com/bait. Also Sarfati, J., Dawkins playing bait and switch with guppy selection; creation.com/guppy-selection. Return to text.
- Kerkut, G.A. (1927–2004); Implications of Evolution, p. 157, Pergamon, Oxford, UK, 1960; creation.com/kerkut. Return to text.
- Perhaps ironically, the first part of the name Chernobyl comes from ‘black’ in the Ukrainian and Russian languages, after a common black weed there. Return to text.
- Halley, K., Evolution: just a change in allele frequencies? 2015; creation.com/evolution-allele-frequencies. Return to text.
- Ambler, M., Natural selection ≠ evolution, Creation 34(2):38–39, 2012; creation.com/natural-selection-evolution. Return to text.
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