Though scientists argue about the details of how evolution occurs and the types of evolution, they almost universally agree that evolution is true. The fossil record, homologies and scientific experiments confirm that evolution can and does exist.
The fossil record, while incomplete, shows a plethora of evolutionary changes in living organisms over the last 4 billion years. Intermediate states between ancient forms and recent descendants show that organisms evolved from one form to another. One example are fossils showing the transitional state between horse ancestors that lived 55 million years and horses today. The fossil record shows a four-toed foot going to a transitional state with three toes to one toe with two vestigial toes and finally becoming the current horse hoof.