Darwin definitely had many ideas on how to convince the readers about how evolution through natural selection was the correct form of evolution. One of his ideas on how evolution through natural selection was correct was the fact that when environments change, the animals living there either died off or evolved to survive in its new habitat. This has been a pattern throughout history. When the habitats change, only the strongest will survive. Nature goes through patterns of over population and depopulation, and in these dangerous increases and decreases, only a certain amount of the species will survive because of natural selection. “The extinction of species and of whole groups of species, which has played so conspicuous a part in the history of the organic world, almost inevitably follows on the principle of natural selection; for old forms will be supplanted by new and improved forms.” ( Darwin, Pg. 497)
This argument to me is very convincing to me because we have fossil records and other records of how animals either died or adapted to their new environments. Mammals most of the time decreased in body size because it made it easier for them to survive. The Homo sapiens family tree is a long and diverse timeline on how humans have adapted to certain elements and became the most dominant creature on the face of the earth. Evolving through natural selection is the only way how to explain how certain animals have evolved and changed throughout the years when we look at their fossil records.