Charles Darwin wrote the influential book "On the Origin of Species," published in 1859, which introduced the theory of evolution by natural selection. In this groundbreaking work, Darwin presented evidence from his observations during the voyage of the HMS Beagle and subsequent studies, arguing that species evolve over time through the process of natural selection, where those with advantageous traits are more likely to survive and reproduce. The book challenged prevailing views on creation and established a scientific framework for understanding biological diversity. Darwin's ideas revolutionized biology and have had profound implications for various fields, including genetics, anthropology, and ecology.