Over the course of time, evolution the genetic makeup of a population

diversified

Through random genetic mutations of a species over time, beings with unique characteristics emerged. Based on the suitability of the adaptation to the environment, the beings would either be able to successfully reproduce, or not, and perish. Successful adaptations would be passed down to children, resulting in the adaptations persisting at least in the short term. Charles Darwin is an excellent author to study to learn more about the theory of evolution.