Which branch of science deals with the evolution and diversity of species? Evolution. More precisely, evolutionary biology studies how inherited characteristics change across generations and how those changes produce the diversity of life.
The field grew from Charles Darwin and Alfred Russel Wallace’s explanation of natural selection. Darwin presented the theory in On the Origin of Species in 1859, arguing that individuals with advantageous heritable traits tend to leave more offspring. Modern evolutionary biology combines this idea with genetics, including mutation, gene flow and genetic drift.
Evolutionary scientists investigate speciation, adaptation, common ancestry and extinction. They use evidence from fossils, comparative anatomy, geographic distribution, behavior and DNA. The modern synthesis of the 1930s and 1940s united Darwinian selection with population genetics, establishing the scientific framework used today.
A common mix-up is choosing paleontology, which studies ancient life and fossils. Paleontology can provide important evidence for evolution, but it is not the overall science of evolutionary change. Astronomy and geology may contribute relevant evidence, yet neither primarily studies the history and diversity of living species.