Module 8: Evolution and Natural Selection

Scientists use the history provided by the fossil record to explore how life on Earth has changed over time. In this module, you studied the theory of evolution. By comparing the fossils of organisms, scientists theorize that species evolve due to pressures from the environment, movement between populations, and other changes to their genetics. The primary mechanism for evolution is natural selection, which is based on the idea that some individuals within a population have phenotypes that make them better suited for the environment in which they live. Because those individuals are better suited for the environment, they survive and have the ability to reproduce, which means that they pass on those traits that made them better suited for the environment. Natural selection can cause the appearance of new species.