Why is it important? • The theory of evolution had existed for many years. What was needed was a theory on how it worked. There were many theories that were proposed, but they were insufficient and lacked evidence. The theory that is supported by evidence is the theory of natural selection.
Theory of Natural Selection • Who? Wallace and Darwin • When? 1858
What is the theory? • There are variations within a species. These variations must be genetically based—in the genes (Mutations, changes in the DNA, cause new variations). • Some variations may allow the organism to be better adapted to their environment. • Those better adapted to their environment will survive and be able to reproduce. • These favorable variations will thus be passed down to each generation. • This process thus can lead to a new species. • Environmental factors can influence which traits allow an organism to survive.