Evolution- a gradual process in which something changes into a different and usually more complex or better form. The theory of evolution is a theory that many can argue to be true. Others will argue that it is not true. I believe that the theory of evolution is true. How do you truly know that evolution has occurred? We know because of the many pieces of evidence that scientists have found. Evidence like chemical and anatomical similarities of related life forms. Darwin pointed out that forelimbs of most animals are very similar, but are used for different reasons. From this he believed that these species have came from a common ancestor. Which means they evolved from that ancestor. The second piece of evidence of why i believe in the theory of evolution is vestigial structures. Vestigial structures are structures that serve no purpose. Most organisms have organs that serve no useful function at all. Like humans have a tailbone at the end of their spine and snakes have tiny pelvic bones and limb structures. They serve no purpose at all. Organisms that have vestigial structures most likely have a common ancestor to those whom that structures is still in use. In conclusion, to why i believe in the questionable theory of evolution is because of the chemical and anatomical similarities of related life forms. Which concludes that organisms evolved from a common ancestor. Also the unused structures called vestigial structures. Which seem to have no purpose at all and the organism can function properly without it. In the end those are the reason why I believe in the very complex theory of evolution.