The Theory of Evolution was the thought that all living species would change over time through natural selection. They change over time as the result of changes in physical or behavioral traits that are passed down from generation to generation. The traits are beneficial to the animal by it helping it live in the habitats it lives in. The survival of the fittest is what Charles Darwin called it. On his travels to the Galápagos Islands, with the Finch population he saw that each bird was a finch but observed that each had a different beak. Seeing that the birds have inherited variations in the bill shape that's some birds having wide deep bills and other having thinner bills. During a time where the rainfall was a lot more than normal because of the storm , the large hard seeds that large birds ate were reduced in number however there was an abundance of small soft seeds for the small billed birds to eat. Therefore, in the future years the small birds population grew better than the big billed birds did.
At the time the majority of the people followed the thought of the church. The belief that God created everything and nothing ever changed. So Charles theory wasn't too in favor of the people in the beginning, they thought he was crazy. The church was in serious doubt of his theory. Something like this was going to be difficult for people to believe. No one would put anything to invest in a thought so out of the ordinary. Although with knowing something like this Charles Darwin could've have been a dangerous man.