Essay on Charles Darwin's Theory of Evolution by Natural Selection

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Charles Darwin's theory of evolution centres on the idea that species compete to survive, and favorable characteristics are passed on from one generation to the next.

Darwin said that evolution took place by a process of natural selection or survival of the fittest. This meant that the animals and plants best suited to their surroundings survived and were able to pass on their genes to their offspring. The ones that weren't best suited died off and didn't get the chance to reproduce. Animals and plants had to change or evolve due to environmental pressures. Over millions of years the conditions on the Earth have changed tremendously, the environmental conditions we have now are very
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Darwin noted four things from his observations:

1. All organisms produce an abundance of offspring, many more than is necessary

2. There is a fairly constant population size over time for any particular organism

3. Within a species there is a wide range of features, due to different alleles

4. Some variations are passed on and inherited by the offspring

From these Darwin decided that all organisms struggle for survival and so have to produce many offspring to ensure that some do survive.

He also concluded that for a species to survive, the best (or 'fittest') of them must survive long enough to reproduce and pass on their genes.

It has three essential parts:

It is possible for the DNA of an organism to occasionally change, or mutate. A mutation changes the DNA of an organism in a way that affects its offspring, either immediately or several generations down the line.

The change brought about by a mutation is either beneficial, harmful or neutral. If the change is harmful, and then it is unlikely that the offspring will survive to reproduce, so the mutation dies out and goes nowhere. If the change is beneficial, then it is likely that the offspring will do better than other offspring and so will reproduce more. Through reproduction, the beneficial mutation spreads. The process of culling bad mutations
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