Everybody is familiar with the accident at reactor four of the Chernobyl nuclear power plant in 1986. There is a film about it which is excellent by the way. It released the largest amount of radioactive material into the environment in human history.
And still, today, as you reach Chernobyl, if you are carrying a Geiger counter it gets noisier and there are less people and, interestingly, the tree frogs become black. The blackness is due to the pigment melanin in their skin.
The scientists have decided that 10-15 frog generations ago when the accident occurred, frogs with the darkest colouration were more likely to survive. And because they survived, they passed on their genes. This is an example of almost immediate evolution as per Darwin’s theory.
They tried to figure out why dark colouration protects against nuclear radiation. They decided that dark skin neutralises free radicals and reduces DNA damage. It has also been proposed that melanin acts as a buffering mechanism against ionising radiation.
We know that darker skinned individuals are better protected against the effects of solar radiation, and they believe that the same sort of protection is offered to black frogs against the radiation experienced in the aftermath of the catastrophic accident.
The darkest frogs were fortunate enough to survive inside what is now called the exclusion zone. The scientists’ findings come from research published in the journal Evolutionary Applications. They sampled almost 200 frogs from inside and outside the exclusion zone.
The nearer they got to the areas of high radiation levels the more melanin they noticed in the frogs pigmentation and in the depths of the exclusion zone which was set up in 1996, the normally green amphibians as you see in the photograph were almost black as you also see in the photograph.
Melanin is a pigment which is in all animals including humans and, in my specialty, domestic cats! It is the melanin pigmentation in domestic cats’ hair strands which, for example, produces the tabby coat together with pheomelanin which is banded with melanin to produce that pattern.
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