Charles Darwin was an English naturalist, geologist, and biologist best known for developing the theory of evolution by natural selection. His seminal work, On the Origin of Species (1859), proposed that all species of life have descended from a common ancestor and that species evolve over time through a process he called natural selection, where organisms better adapted to their environment tend to survive and reproduce
. Darwin's ideas were shaped by his observations during a five-year voyage on the HMS Beagle (1831–1836), where he studied plants, animals, and fossils, particularly noting variations among species on the Galápagos Islands. These observations led him to conclude that species are not fixed but change over time in response to environmental pressures
. Beyond On the Origin of Species , Darwin also wrote extensively on human evolution, sexual selection, and botany, publishing works such as The Descent of Man (1871) and The Expression of the Emotions in Man and Animals (1872). His contributions fundamentally transformed biological science by providing a unifying explanation for the diversity of life
. Darwin's theory initially met with resistance but eventually became the cornerstone of modern biology, profoundly influencing both scientific and philosophical thought
. He continued his scientific work until his death in 1882 and is buried in Westminster Abbey as a mark of his lasting legacy
