After exploring the Galapagos islands many years ago, Charles Darwin made important discoveries that would change the world of science forever. His expedition found that there were several organisms that settled on different islands were the same animal, only they had their own unique characteristics. For example, birds known as finches have different beaks on each island. Darwin theorized that these beaks were tools for feeding on the resources that their specific island contained. Finches adapted to their certain environment, evidence of natural selection. Natural selection is when an organism changes to improve survival, but before the finches could have changed they would have had to have been the same bird. Darwin believed that every organism came from a common descent, meaning that animals that could look nothing alike would be related. There was no way of proving his theories at the time, until the discovery of DNA. The discovery of the macromolecule proved that animals do indeed evolve. DNA codes what we look like and who we are, whether we are a fish or a human. According to DNA and scientific research fish and humans have common ancestors. When an embryo, humans have the beginning of what seems to be gills. Over time the gill-ice structure turns into the small ears inside our ears. Diversity is made by mutation of the DNA, without mutation every organism would stay the same. This information has advanced scientific research very much and will hopefully lead to many new discoveries in the future.