Researching Charles Darwin's theory of evolution

Darwin proposed the theory of evolution by natural selection to explain animals' adaptations. The theory is based on the idea that within a species, there are variations and competition. Within a habitat, some individuals will be better-adapted and others will be less-well-adapted. The better-adapted individuals are more likely to survive and reproduce, passing on these advantageous characteristics. Over a huge period of time, the advantageous characteristics become normal in the species (or can create a new species).