Charles Darwin was born in 1809 in Shrewsbury, England. His father, a doctor, had high hopes that his son would earn a medical degree at Edinburgh University in Scotland, where he enrolled at the age of sixteen. It turned out that Darwin was more interested in natural history than medicine—it was said that the sight of blood made him sick to his stomach. While he continued his studies in theology at Cambridge, it was his focus on natural history that became his passion.

In 1831, Darwin embarked on a voyage aboard a ship of the British Royal Navy, the HMS Beagle, employed as a naturalist. The main purpose of the trip was to survey the coastline of South America and chart its harbors to make better maps of the region. The work that Darwin did was just an added bonus.

Darwin spent much of the trip on land collecting samples of plants, animals, rocks, and fossils. He explored regions in Brazil, Argentina, Chile, and remote islands such as the Galápagos. He packed all of his specimens into crates and sent them back to England aboard other vessels.

Upon his return to England in 1836, Darwin’s work continued. Studies of his samples and notes from the trip led to groundbreaking scientific discoveries. Fossils he collected were shared with paleontologists and geologists, leading to advances in the understanding of the processes that shape the Earth’s surface. Darwin’s analysis of the plants and animals he gathered led him to question how species form and change over time. This work convinced him of the insight that he is most famous for—natural selection. The theory of natural selection says that individuals of a species are more likely to survive in their environment and pass on their genes to the next generation when they inherit traits from their parents that are best suited for that specific environment. In this way, such traits become more widespread in the species and can lead eventually to the development of a new species.

In 1859, Darwin published his thoughts about evolution and natural selection in On the Origin of Species. It was as popular as it was controversial. The book convinced many people that species change over time—a lot of time—suggesting that the planet was much older than what was commonly believed at the time: six thousand years.

Charles Darwin died in 1882 at the age of seventy-three. He is buried in Westminster Abbey in London, England.