Darwin created the theory of evolution. A scientific theory is an idea or explanation that is heavily supported by studies, evidence, and data. The evidences that are used to support the theory of evolution include: 1.) the fossil record, 2.) chemical and anatomical similarities amongst organisms, and 3.) the geographic distribution of related species.
1. The fossil record shows how organisms have changed over time. More and more fossils are being found over time. Thus, what was once thought to be gaps in the fossil record or punctuated equilibrium are now thought to be due to incomplete fossil records.
2. Chemical and anatomical similarities
Gel electrophoresis is used to show similarities between the DNA, RNA, and protein sequences between species. The more sequences that two species share, the more closely related they are thought to be.
Homologous structures are anatomical parts that are found in different species bt share enough similarities to assume that these structures steamed from a common ancestor. For example, the forearm of a horse, human and dog are homologous structures.
3. Geographic distribution
It is thought that all continents were once connected in one large landmass known as Pangea. This may account for similar species (such as the horse and zebra) from existing across the sea from one another. Their differences would e explained by Darwin's theory or natural selection and adaptations.
Geographic distribution can also be used to explain why there are such unique species on isolated areas such as the Galapagos islands. Other examples would be Haiti and New Zeeland. Each of these places had a great number of plant, insect, and bird species that were found nowhere else in the world because the life forms in these areas have been evolving in isolation from the rest of the world for millions of years.