Fossil evidence provides a record of how creatures evolved and how this process can be represented by a 'tree of life', showing that all species are related to each other. Fossils can also be used to date rocks. Studying fossil pollen and other fossils helps scientists to learn more about climate change. Based on the evidence these fossils provide, we can find out whether or not climate has changed in the past, and how fast and frequently climate changes occurred. Scientists can reconstruct a general picture of an ancient environment by collecting information about the soil and the plant and animal remains that are found at a site. Comparisons of living plants and animals with these ancient remains can then indicate the types of environments that existed in the past.