The fittest survive, but what does that mean?
Even now there are still people who do not fully understand the tenet of the survival of the fittest and believe it has something to do with winners and losers of a combat and physical strength. However, that even the smallest individual could be the fittest individual perhaps under conditions of a food shortage or an availability of shelters best suitable for small individuals and that an individual which is weak, but smarter than others could become the “fittest” through the process of selection is something that needs to be emphasized. To explain natural selection, zoologists often use the example of the white and dark specimens of the peppered moth Biston betularia in England: the originally rather rare dark variety became increasingly more common as industrial pollution increased and the whitish tree trunks of birch trees turned grey with soot. When pollution levels subsided and the environment became cleaner again, it was the lighter coloured variety that gained the upper hand once more.