What is Evolution? Evolution is the theory that all living things in the world have come into being through a non-guided, natural process starting from a primeval mass of subatomic particles and radiation, over 20 billion years ago (History). This theory says that all living things have increased intelligence or have changed in other ways over many, many years. The theory of evolution hasn’t been around for ever. Before the 20th century, people wanted to understand the world around them, but many of them believed that God created everythi ....