Evolution

Evolution is the change in the genetic makeup of a population over multiple generations. The theory was referred to as descent with modification by Charles Darwin, who argued that all life descended from a common ancestor. Evolution explains the diversity of species and similarities between species' fossils, anatomies, embryos, and DNA. These similarities allow scientists to piece together evolutionary relationships and identify species' shared ancestry.

All life on Earth possesses genetic material, and members of the same species share most of theirs, with small variations. A few of these differences correspond to traits that make some organisms better suited to their environment than others. Through natural selection, these organisms are more likely to survive, reproduce, and pass on their traits, which alters the population's future gene pool. Other evolutionary forces, such as mutations, also introduce changes, which can accumulate over time to produce new species.

Evolution has been directly observed in organisms with short lifespans, including fish, mosquitoes, and microbes. Through artificial selection, humans have directed evolution by purposely breeding specific organisms—crops, livestock, and dogs—to pass on preferred traits. Scientists also use evolutionary biology to study antibiotic resistance, track diseases, facilitate drug discovery, develop vaccines, and engineer enzymes for industrial use.