Final answer:
Charles Darwin's main approach toward science was the development of the theory of evolution by natural selection, which explains how all living organisms have developed from earlier forms of life.
Step-by-step explanation:
Charles Darwin's main approach toward science was the development of the theory of evolution by natural selection. This theory states that all living organisms have developed from earlier forms of life and explains why evolution occurs. Darwin spent years observing and collecting specimens, especially on the Galápagos Islands, which provided crucial evidence supporting his theory.