The Dummies guide to Evolution

A brief tutorial for those who don't have time to read all the literature.
The discovery that the earth was millions of years old, occurred long before Darwin came up with his theory of evolution. The geological evidence was compelling and nobody questioned this fact.

There were various theories of evolution before Darwin proposed his own, known as Evolution by Natural Selection. Lamarck for example proposed that adaptions by individuals were inherited by their offspring.

Darwin uses a very basic example of pidgeon breeders who actively select characteristics of birds and breed those characteristics into the next generation. Darwin made the mental leap and extrapolated that nature, working on a longer timescale than a pidgeon breeder could achieve the same result. The reason nature chooses and favors certain characteristics is because these characteristics give an individual an advantage in survival. Having this advantage means the opportunity to reproduce is increased. This means the chance to pass on advantageous characteristics is increased.

In our modern world, we can observe more meaningful acts of evolution that have a direct effect on our wellbeing. The humble flu virus for example is capable of mutating faster than man can find drugs to fight it. Another example is bacteria. The enormous (exponential) growth rate of bacteria means that there is always a few individual organisms that survive any attempt at eradication. Being a simple organism, bacteria and viruses can have millions of mutations at any one reproductive cycle. In effect, bacteria and viruses are constantly mutating to adapt to their environment - the human efforts to eradicate them.

The next contentious aspect of evolution theory is that if one grudgingly accepts that evolution does occur, it is incomprehensible to accept that species evolve into new species.
The most celebrated image is that of apes evolving into human beings. From the time that Darwin proposed his theory, this has been the most passionately held argument used to refute Darwin.
Let's clear this up. It isn't an absolute imperative that the human species evolved from the current known ape species in existence. In fact, it was never core argument in Darwin's theory.
At best, we might eventually find archaeological evidence that shows the common ancestor from which both human species and all other ape species evolved. Commonly known as the "missing Link".
So, nobody is expected to accept the idea that humans evolved directly from chimpanzees in order to accept the theory of evolution. This is pure fallacy.

Lets not ignore the fact that Charles Darwin was an extremely religious man. He faith in God was very strong. Over time, as his theory of Evolution formed in his head, he became extremely distressed at the realization that scientific facts that led to the formation of his theory of evolution showed that the existence of God was irrelevant to the formation of life on earth. In effect, his core beliefs were shaken. It is for this reason that Darwin withheld his theory for many years before finally publishing his book, The Origin of the Species.