In 2008, a Gallup poll in the US showed that 44% of people believed that God created human beings pretty much in their present form at some time in the last 10,000 years. In the UK, the Ipsos MORI poll of 2006 showed the equivalent figure to be around 22%.
For many people then, the whole idea of evolution is considered as false. Since many of those people who think that way are in positions of power, for example, running educational establishments or political organisations, there is a powerful lobby against evolution.
Scientists though regard evolution as the most successful scientific theory ever, with so much independent evidence, that they cannot understand why it should ever be rejected. So the question is, if the evidence is so clear and obvious, why isn't it accepted?
One answer is that perhaps the evidence is not as clear cut, or as abundant, as scientists claim. Another is that perhaps, the theory of evolution is not well-understood and for that reason, is not accepted. A third possibility is that the evidence itself has rarely been presented in its abundance with an explanation that is convincing. Another possibility is that vested interests have steered potential students away from the evidence.
Richard Dawkins has published a great deal of scientific material on the theory of evolution, most notable in his book The Selfish Gene, which building on Darwin's theory of evolution, explained evolution from the point of view of the gene. His further work explored the implications for evolution of new discoveries in biology, particularly genetics. All of this could well have been over the heads of the general reader.
It was the recognition that the demand for an exposition of the evidence was reasonable, that prompted Dawkings to write The Greatest Show On Earth. Although evolution is demonstrably a fact, many people still do not accept it. Dawkins sets out to present the evidence.
Biologists make a distinction between the fact of evolution, and the theory of evolution, namely natural selection. That evolution is a fact is based on the demonstrable evidence that all living things are related, are cousins, and somewhere along the line, have common ancestors. The theory of evolution is that theory which explains how evolution works, what drives the successive modification of species. Natural selection is a theory that explains the fact of evolution and although some biologists offer modifications to the theory, or even different theories, they are all trying to explain adequately that fact: evolution.