As you should know, all species have natural variation and mutation. Just look at the human species, for example. Everyone is different. Different
eye colours, different face shapes, different bodies e.t.c. The same is true of most of the animal kingdom - you will always get variation. We don't just have normal everyday bipedal "healthy" humans, we have people with mental disorders and physical disorders. We have conjoined twins and people with dwarfism and blind people and deaf people... you get the idea.
So now let's move on to the peppered moth. 200 or so years ago, the peppered moth looked much like this.
As you can see, it's quite light-colou
red. These moths like to hang out on trees, nicely camouflaged against the bark so that birds couldn't see them. There were a few peppered moths which were a bit darker but that was only 0.01% of the population, as they were easily spotted by birds.
However, at the dawn of the industrial revolution in the UK, things began to change. Factories were being built everywhere, polluting the atmosphere with their smoke. The pollution from the smoke started to change the colour of the bark on the surrounding trees, making it darker.
Now, as the trees got darker, obviously the peppered moths started becoming easier for the birds to spot. The peppered moth population dropped dramatically. What we do begin to see, however, is this.
Yes, the lighter moths are easier to see, but there was still that 0.01% of the peppered moth species which was much darker. As a result, these moths actually did a lot better at hiding from the
birds, thus the lighter coloured peppered moths gradually died out and the darker moths continued to reproduce and spread their superior genes.
This is a classic example of "survival of the fittest". The darker moths were more successful so the peppered moth evolved from the light colour into the darker colour. Surprisingly simple, isn't it?
It also illustrates how well organisms can adapt to their surroundings over time. It's not magic, it's not "chance", it's the pure power of nature and if it didn't happen, we wouldn't be here today.
In a later blog I might attempt to apply some of the themes of this blog onto human evolution and our African ancestors. However for now, I'll leave you with this very simple example of natural selection as food for thought. Ta ta for now.
