Natural selection is a simple tautology that should really be obvious.
- If an inherited trait helps an animal or plant to survive and reproduce a higher percentage of organisms with that trait will survive and reproduce than the percentage without that trait. That is known as a favourable trait.
- If an inherited trait makes it harder for an animal or plant to survive or reproduce a lower percentage of organisms with that trait will survive and reproduce than the percentage that survive without the trait. That is known as an unfavourable trait.
- Over the generations the proportion of organisms with favourable traits will tend to increase while the proportion with unfavourable traits will tend to decrease.
Natural selection can happen in any situation where something reproduces and passes on its traits. Charles Darwin and Alfred Russell Wallace developed this idea independently. Natural selection affects the genes of living organisms.
Over time natural selection causes populations to differentiate as they adapt to new environments. Gradually new subspecies and new species are formed. This is known as the Theory of Evolution by natural selection.
In a slightly different way natural selection also affects Memes, which are ideas that people copy and pass on to other people - or more correctly ideas which cause people to copy them and pass on.
- Natural selection People who can't understand natural selection after this clear introduction from Berkley University are probably wildly theist and don't want to see reality. If you are debating about evolution on as Internet discussion forum linking here can at least show the more reasonable people at the forum that Natural selection makes sense. If you can seriously disturb people's faith that might get you banned from some religious forums. Then do you want to take part in that type of forum?
Adapted from Atheism Wiki